HashMap源码解读以及详细中文注释(一)

抄写源码,和添加详细中文注释.将以下代码拷贝可断点加深理解.
自定义HashMap类:

import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.Serializable;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.*;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.Consumer;
import java.util.function.Function;

/**
 *
 */
public class MyHashMap<K, V> extends AbstractMap<K, V>
        implements Map<K, V>, Cloneable, Serializable {

    transient Set<K> keySet;
    transient Collection<V> values;

    private static final long serialVersionUID = 3624958245468L;
    static final int DEFAULT_INITIAL_CAPACITY = 1 << 4;// 默认初始化table的长度16
    static final int MAXIMUM_CAPACITY = 1 << 30;// 1073741824
    static final float DEFAULT_LOAD_FACTOR = 0.75f;//默认加载因子
    static final int TREEIFY_THRESHOLD = 8;// 树化的阈值(链表长度超过此值就会组装成红黑树)
    static final int UNTREEIFY_THRESHOLD = 6;// 从树变成链表的阈值
    static final int MIN_TREEIFY_CAPACITY = 64;// 树化时table的最小长度

    static class Node<K, V> implements Map.Entry<K, V> {
        final int hash;
        final K key;
        V value;
        MyHashMap.Node<K, V> next;

        Node(int hash, K key, V value, MyHashMap.Node<K, V> next) {
            this.hash = hash;
            this.key = key;
            this.value = value;
            this.next = next;
        }

        public final K getKey() {
            return key;
        }

        public final V getValue() {
            return value;
        }

        public final String toString() {
            StringBuilder rstStr = new StringBuilder();
            rstStr.append(key);
            rstStr.append("=");
            rstStr.append(value);
            if (Objects.nonNull(this.next)) {
                rstStr.append(" --> ");
                rstStr.append(this.next.toString());
            }
            return rstStr.toString();
        }

        public final int hashCode() {
            return Objects.hashCode(key) ^ Objects.hashCode(value);
        }

        public final V setValue(V newValue) {
            V oldValue = value;
            value = newValue;
            return oldValue;
        }

        public final boolean equals(Object o) {
            if (o == this)
                return true;
            if (o instanceof Map.Entry) {
                Map.Entry<?, ?> e = (Map.Entry<?, ?>) o;
                if (Objects.equals(key, e.getKey()) &&
                        Objects.equals(value, e.getValue()))
                    return true;
            }
            return false;
        }
    }

    static final int hash(Object key) {
        int h;
        return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);
    }

    static Class<?> comparableClassFor(Object x) {
        if (x instanceof Comparable) {
            Class<?> c;
            Type[] ts, as;
            Type t;
            ParameterizedType p;
            if ((c = x.getClass()) == String.class) // bypass checks
                return c;
            if ((ts = c.getGenericInterfaces()) != null) {
                for (int i = 0; i < ts.length; ++i) {
                    if (((t = ts[i]) instanceof ParameterizedType) &&
                            ((p = (ParameterizedType) t).getRawType() ==
                                    Comparable.class) &&
                            (as = p.getActualTypeArguments()) != null &&
                            as.length == 1 && as[0] == c) // type arg is c
                        return c;
                }
            }
        }
        return null;
    }

    static int compareComparables(Class<?> kc, Object k, Object x) {
        return (x == null || x.getClass() != kc ? 0 :
                ((Comparable) k).compareTo(x));
    }

    static final int tableSizeFor(int cap) {
        int n = cap - 1;
        n |= n >>> 1;
        n |= n >>> 2;
        n |= n >>> 4;
        n |= n >>> 8;
        n |= n >>> 16;
        return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
    }

    transient MyHashMap.Node<K, V>[] table;
    transient Set<Map.Entry<K, V>> entrySet;
    transient int size;
    transient int modCount;
    int threshold;
    final float loadFactor;

    public MyHashMap(int initialCapacity, float loadFactor) {
        if (initialCapacity < 0)
            throw new IllegalArgumentException("Illegal initial capacity: " +
                    initialCapacity);
        if (initialCapacity > MAXIMUM_CAPACITY)
            initialCapacity = MAXIMUM_CAPACITY;
        if (loadFactor <= 0 || Float.isNaN(loadFactor))
            throw new IllegalArgumentException("Illegal load factor: " +
                    loadFactor);
        this.loadFactor = loadFactor;
        this.threshold = tableSizeFor(initialCapacity);
    }


    public MyHashMap(int initialCapacity) {
        this(initialCapacity, DEFAULT_LOAD_FACTOR);
    }

    public MyHashMap() {// 创建map时只给加载因子赋值,不创建node数组.
        this.loadFactor = DEFAULT_LOAD_FACTOR; // all other fields defaulted
    }

    public MyHashMap(Map<? extends K, ? extends V> m) {
        this.loadFactor = DEFAULT_LOAD_FACTOR;
        putMapEntries(m, false);
    }

    final void putMapEntries(Map<? extends K, ? extends V> m, boolean evict) {
        int s = m.size();
        if (s > 0) {
            if (table == null) { // pre-size
                float ft = ((float) s / loadFactor) + 1.0F;
                int t = ((ft < (float) MAXIMUM_CAPACITY) ?
                        (int) ft : MAXIMUM_CAPACITY);
                if (t > threshold)
                    threshold = tableSizeFor(t);
            } else if (s > threshold)
                resize();
            for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {
                K key = e.getKey();
                V value = e.getValue();
                putVal(hash(key), key, value, false, evict);
            }
        }
    }

    public int size() {
        return size;
    }

    public boolean isEmpty() {
        return size == 0;
    }

    public V get(Object key) {
        MyHashMap.Node<K, V> e;
        return (e = getNode(hash(key), key)) == null ? null : e.value;
    }

    final MyHashMap.Node<K, V> getNode(int hash, Object key) {
        MyHashMap.Node<K, V>[] tab;
        MyHashMap.Node<K, V> first, e;
        int n;
        K k;
        // 校验table非空,且长度>0,且根据key的hash值对应的下标获取到数组的头节点不为空
        if ((tab = table) != null && (n = tab.length) > 0 &&
                (first = tab[(n - 1) & hash]) != null) {
            // 首先判断头节点是否满足条件,满足就直接返回头节点
            if (first.hash == hash &&
                    ((k = first.key) == key || (key != null && key.equals(k))))
                return first;
            // 头节点的next节点不为空则接着往下比较
            if ((e = first.next) != null) {

                if (first instanceof MyHashMap.TreeNode) {
                    // 遍历树节点比较,满足就直接返回
                    return ((MyHashMap.TreeNode<K, V>) first).getTreeNode(hash, key);
                }
                do {
                    // 遍历链表节点比较,满足就直接返回
                    if (e.hash == hash &&
                            ((k = e.key) == key || (key != null && key.equals(k)))) {
                        return e;
                    }
                } while ((e = e.next) != null);
            }
        }
        return null;
    }

    public boolean containsKey(Object key) {
        return getNode(hash(key), key) != null;
    }

    public V put(K key, V value) {
        return putVal(hash(key), key, value, false, true);
    }

    final V putVal(int hash, K key, V value, boolean onlyIfAbsent,
                   boolean evict) {
        MyHashMap.Node<K, V>[] tab;
        MyHashMap.Node<K, V> p;
        int n, i;
        // new的时候不创建node数组,首次put值时创建node数组
        if ((tab = table) == null || (n = tab.length) == 0) {
            n = (tab = resize()).length;
        }
        // 判断新put的key的索引位置上的元素为空, 即情况1
        if ((p = tab[i = (n - 1) & hash]) == null) {
            // 直接将K,V构造一个node对象并放入到table数组中
            tab[i] = newNode(hash, key, value, null);
        } else {
            MyHashMap.Node<K, V> e;
            K k;
            // 新put进来的key和之前的keyhash值相等且equals()也返回true
            if (p.hash == hash &&
                    ((k = p.key) == key || (key != null && key.equals(k)))) {
                e = p;
            } else if (p instanceof MyHashMap.TreeNode) {
                // 原有节点的类型为treeNode,则将新put的key加入到树中
                e = ((MyHashMap.TreeNode<K, V>) p).putTreeVal(this, tab, hash, key, value);
            } else {
                for (int binCount = 0; ; ++binCount) {
                    // 原有节点的next的值为null
                    if ((e = p.next) == null) {
                        // 创建新节点,并将原有节点的next指向新创建的节点.
                        p.next = newNode(hash, key, value, null);
                        // -1 for 1st, 当同一位置的节点数>=8时 ,就创建红黑树
                        if (binCount >= TREEIFY_THRESHOLD - 1) {
                            // 构建红黑树
                            treeifyBin(tab, hash);
                        }
                        break;
                    }
                    // 链表中已存在节点的hash值与新put的key的哈希值相等且equals()返回true,则退出循环不再往下比较了
                    if (e.hash == hash &&
                            ((k = e.key) == key || (key != null && key.equals(k)))) {
                        break;
                    }
                    p = e;
                }
            }
            if (e != null) {
                // key已经存在 则返回对应的原有的value
                V oldValue = e.value;
                if (!onlyIfAbsent || oldValue == null) {
                    // 把新put的value付给当前的node
                    e.value = value;
                }
                afterNodeAccess(e);
                return oldValue;
            }
        }
        ++modCount;
        if (++size > threshold) {
            // 添加的节点个数超过临界值就会扩容
            resize();
        }
        afterNodeInsertion(evict);
        return null;
    }

    final MyHashMap.Node<K, V>[] resize() {
        MyHashMap.Node<K, V>[] oldTab = table;
        int oldCap = (oldTab == null) ? 0 : oldTab.length;
        int oldThr = threshold;// 临界值
        int newCap, newThr = 0;
        if (oldCap > 0) {
            // 原有的数组长度>= 数组允许的最大长度
            if (oldCap >= MAXIMUM_CAPACITY) {
                // 将扩容的阈值设置为int的最大值
                threshold = Integer.MAX_VALUE;
                return oldTab;
            } else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY &&
                    oldCap >= DEFAULT_INITIAL_CAPACITY) {
                // (原有的数组长度扩大2倍) < 数组允许的最大长度 且 原有的数组长度 >= 默认数组长度,扩容的阈值扩大2倍
                newThr = oldThr << 1; // double threshold
            }
        } else if (oldThr > 0) {
            newCap = oldThr;
        } else {               // zero initial threshold signifies using defaults
            newCap = DEFAULT_INITIAL_CAPACITY;// 数组为空时赋数组默认长度值 16
            newThr = (int) (DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);// 默认临界值0.75*16 = 12
        }
        if (newThr == 0) {
            float ft = (float) newCap * loadFactor;
            newThr = (newCap < MAXIMUM_CAPACITY && ft < (float) MAXIMUM_CAPACITY ?
                    (int) ft : Integer.MAX_VALUE);
        }
        threshold = newThr;
        @SuppressWarnings({"rawtypes", "unchecked"})
        MyHashMap.Node<K, V>[] newTab = (MyHashMap.Node<K, V>[]) new MyHashMap.Node[newCap];
        table = newTab;
        if (oldTab != null) {
            // 数组长度超过阈值,进行扩容
            for (int j = 0; j < oldCap; ++j) {
                MyHashMap.Node<K, V> e;
                if ((e = oldTab[j]) != null) {
                    // 将原有数组的对应位置置空
                    oldTab[j] = null;
                    if (e.next == null) {
                        // 原数组索引位置只有一个元素,则根据hash值重新确定在新数组中的索引位置
                        newTab[e.hash & (newCap - 1)] = e;
                    } else if (e instanceof MyHashMap.TreeNode) {
                        // 节点是树节点类型
                        ((MyHashMap.TreeNode<K, V>) e).split(this, newTab, j, oldCap);
                    } else {
                        // 保留顺序,拆分链表
                        MyHashMap.Node<K, V> loHead = null, loTail = null;// 原索引位置的头节点和尾节点
                        MyHashMap.Node<K, V> hiHead = null, hiTail = null;// 新索引位置(原索引+原数组长度)的头节点和尾节点
                        MyHashMap.Node<K, V> next;
                        do {
                            next = e.next;
                            // 节点的哈希值 与 原数组长度 等于零,则放在原索引位置的链表中.否则放在新索引位置的链表中
                            if ((e.hash & oldCap) == 0) {
                                if (loTail == null) {
                                    loHead = e;
                                } else {
                                    loTail.next = e;
                                }
                                loTail = e;
                            } else {
                                if (hiTail == null) {
                                    hiHead = e;
                                } else {
                                    hiTail.next = e;
                                }
                                hiTail = e;
                            }
                        } while ((e = next) != null);
                        if (loTail != null) {
                            loTail.next = null;
                            newTab[j] = loHead;
                        }
                        if (hiTail != null) {
                            hiTail.next = null;
                            // 将拆分后的链表头部的节点,放到新数组的索引为: 原节点的索引+原数组的长度的位置
                            newTab[j + oldCap] = hiHead;
                        }
                    }
                }
            }
        }
        return newTab;
    }

    // 树化
    final void treeifyBin(MyHashMap.Node<K, V>[] tab, int hash) {
        int n, index;
        MyHashMap.Node<K, V> e;
        if (tab == null || (n = tab.length) < MIN_TREEIFY_CAPACITY)
            resize();// 如果table的长度小于最小树化的长度(默认64),则对数组进行扩容
        else if ((e = tab[index = (n - 1) & hash]) != null) {
            MyHashMap.TreeNode<K, V> hd = null, tl = null;
            do {
                MyHashMap.TreeNode<K, V> p = replacementTreeNode(e, null);
                if (tl == null) {
                    hd = p;//设置头节点}
                } else {
                    p.prev = tl;//设置前驱节点
                    tl.next = p;// 设置后继节点
                }
                tl = p;
            } while ((e = e.next) != null);
            if ((tab[index] = hd) != null) {
                hd.treeify(tab);
            }
        }
    }

    public void putAll(Map<? extends K, ? extends V> m) {
        putMapEntries(m, true);
    }

    public V remove(Object key) {
        MyHashMap.Node<K, V> e;
        return (e = removeNode(hash(key), key, null, false, true)) == null ?
                null : e.value;
    }

    final MyHashMap.Node<K, V> removeNode(int hash, Object key, Object value,
                                          boolean matchValue, boolean movable) {
        MyHashMap.Node<K, V>[] tab;
        MyHashMap.Node<K, V> p;
        int n, index;
        if ((tab = table) != null && (n = tab.length) > 0 &&
                (p = tab[index = (n - 1) & hash]) != null) {
            MyHashMap.Node<K, V> node = null, e;
            K k;
            V v;
            if (p.hash == hash &&
                    ((k = p.key) == key || (key != null && key.equals(k))))
                node = p;
            else if ((e = p.next) != null) {
                if (p instanceof MyHashMap.TreeNode)
                    node = ((MyHashMap.TreeNode<K, V>) p).getTreeNode(hash, key);
                else {
                    do {
                        if (e.hash == hash &&
                                ((k = e.key) == key ||
                                        (key != null && key.equals(k)))) {
                            node = e;
                            break;
                        }
                        p = e;
                    } while ((e = e.next) != null);
                }
            }
            if (node != null && (!matchValue || (v = node.value) == value ||
                    (value != null && value.equals(v)))) {
                if (node instanceof MyHashMap.TreeNode)
                    ((MyHashMap.TreeNode<K, V>) node).removeTreeNode(this, tab, movable);
                else if (node == p)
                    tab[index] = node.next;
                else
                    p.next = node.next;
                ++modCount;
                --size;
                afterNodeRemoval(node);
                return node;
            }
        }
        return null;
    }

    public void clear() {
        MyHashMap.Node<K, V>[] tab;
        modCount++;
        if ((tab = table) != null && size > 0) {
            size = 0;
            for (int i = 0; i < tab.length; ++i)
                tab[i] = null;
        }
    }

    public boolean containsValue(Object value) {
        MyHashMap.Node<K, V>[] tab;
        V v;
        if ((tab = table) != null && size > 0) {
            for (int i = 0; i < tab.length; ++i) {
                for (MyHashMap.Node<K, V> e = tab[i]; e != null; e = e.next) {
                    if ((v = e.value) == value ||
                            (value != null && value.equals(v)))
                        return true;
                }
            }
        }
        return false;
    }

    public Set<K> keySet() {
        Set<K> ks = keySet;
        if (ks == null) {
            ks = new MyHashMap.KeySet();
            keySet = ks;
        }
        return ks;
    }

    final class KeySet extends AbstractSet<K> {
        public final int size() {
            return size;
        }

        public final void clear() {
            MyHashMap.this.clear();
        }

        public final Iterator<K> iterator() {
            return new MyHashMap.KeyIterator();
        }

        public final boolean contains(Object o) {
            return containsKey(o);
        }

        public final boolean remove(Object key) {
            return removeNode(hash(key), key, null, false, true) != null;
        }

        public final Spliterator<K> spliterator() {
            return new MyHashMap.KeySpliterator<>(MyHashMap.this, 0, -1, 0, 0);
        }

        public final void forEach(Consumer<? super K> action) {
            MyHashMap.Node<K, V>[] tab;
            if (action == null)
                throw new NullPointerException();
            if (size > 0 && (tab = table) != null) {
                int mc = modCount;
                for (int i = 0; i < tab.length; ++i) {
                    for (MyHashMap.Node<K, V> e = tab[i]; e != null; e = e.next)
                        action.accept(e.key);
                }
                if (modCount != mc)
                    throw new ConcurrentModificationException();
            }
        }
    }

    public Collection<V> values() {
        Collection<V> vs = values;
        if (vs == null) {
            vs = new MyHashMap.Values();
            values = vs;
        }
        return vs;
    }

    final class Values extends AbstractCollection<V> {
        public final int size() {
            return size;
        }

        public final void clear() {
            MyHashMap.this.clear();
        }

        public final Iterator<V> iterator() {
            return new MyHashMap.ValueIterator();
        }

        public final boolean contains(Object o) {
            return containsValue(o);
        }

        public final Spliterator<V> spliterator() {
            return new MyHashMap.ValueSpliterator<>(MyHashMap.this, 0, -1, 0, 0);
        }

        public final void forEach(Consumer<? super V> action) {
            MyHashMap.Node<K, V>[] tab;
            if (action == null)
                throw new NullPointerException();
            if (size > 0 && (tab = table) != null) {
                int mc = modCount;
                for (int i = 0; i < tab.length; ++i) {
                    for (MyHashMap.Node<K, V> e = tab[i]; e != null; e = e.next)
                        action.accept(e.value);
                }
                if (modCount != mc)
                    throw new ConcurrentModificationException();
            }
        }
    }

    public Set<Map.Entry<K, V>> entrySet() {
        Set<Map.Entry<K, V>> es;
        return (es = entrySet) == null ? (entrySet = new MyHashMap.EntrySet()) : es;
    }

    final class EntrySet extends AbstractSet<Map.Entry<K, V>> {
        public final int size() {
            return size;
        }

        public final void clear() {
            MyHashMap.this.clear();
        }

        public final Iterator<Map.Entry<K, V>> iterator() {
            return new MyHashMap.EntryIterator();
        }

        public final boolean contains(Object o) {
            if (!(o instanceof Map.Entry))
                return false;
            Map.Entry<?, ?> e = (Map.Entry<?, ?>) o;
            Object key = e.getKey();
            MyHashMap.Node<K, V> candidate = getNode(hash(key), key);
            return candidate != null && candidate.equals(e);
        }

        public final boolean remove(Object o) {
            if (o instanceof Map.Entry) {
                Map.Entry<?, ?> e = (Map.Entry<?, ?>) o;
                Object key = e.getKey();
                Object value = e.getValue();
                return removeNode(hash(key), key, value, true, true) != null;
            }
            return false;
        }

        public final Spliterator<Map.Entry<K, V>> spliterator() {
            return new MyHashMap.EntrySpliterator<>(MyHashMap.this, 0, -1, 0, 0);
        }

        public final void forEach(Consumer<? super Map.Entry<K, V>> action) {
            MyHashMap.Node<K, V>[] tab;
            if (action == null)
                throw new NullPointerException();
            if (size > 0 && (tab = table) != null) {
                int mc = modCount;
                for (int i = 0; i < tab.length; ++i) {
                    for (MyHashMap.Node<K, V> e = tab[i]; e != null; e = e.next)
                        action.accept(e);
                }
                if (modCount != mc)
                    throw new ConcurrentModificationException();
            }
        }
    }

    // Overrides of JDK8 Map extension methods

    @Override
    public V getOrDefault(Object key, V defaultValue) {
        MyHashMap.Node<K, V> e;
        return (e = getNode(hash(key), key)) == null ? defaultValue : e.value;
    }

    @Override
    public V putIfAbsent(K key, V value) {
        return putVal(hash(key), key, value, true, true);
    }

    @Override
    public boolean remove(Object key, Object value) {
        return removeNode(hash(key), key, value, true, true) != null;
    }

    @Override
    public boolean replace(K key, V oldValue, V newValue) {
        MyHashMap.Node<K, V> e;
        V v;
        if ((e = getNode(hash(key), key)) != null &&
                ((v = e.value) == oldValue || (v != null && v.equals(oldValue)))) {
            e.value = newValue;
            afterNodeAccess(e);
            return true;
        }
        return false;
    }

    @Override
    public V replace(K key, V value) {
        MyHashMap.Node<K, V> e;
        if ((e = getNode(hash(key), key)) != null) {
            V oldValue = e.value;
            e.value = value;
            afterNodeAccess(e);
            return oldValue;
        }
        return null;
    }

    @Override
    public V computeIfAbsent(K key,
                             Function<? super K, ? extends V> mappingFunction) {
        if (mappingFunction == null)
            throw new NullPointerException();
        int hash = hash(key);
        MyHashMap.Node<K, V>[] tab;
        MyHashMap.Node<K, V> first;
        int n, i;
        int binCount = 0;
        MyHashMap.TreeNode<K, V> t = null;
        MyHashMap.Node<K, V> old = null;
        if (size > threshold || (tab = table) == null ||
                (n = tab.length) == 0)
            n = (tab = resize()).length;
        if ((first = tab[i = (n - 1) & hash]) != null) {
            if (first instanceof MyHashMap.TreeNode)
                old = (t = (MyHashMap.TreeNode<K, V>) first).getTreeNode(hash, key);
            else {
                MyHashMap.Node<K, V> e = first;
                K k;
                do {
                    if (e.hash == hash &&
                            ((k = e.key) == key || (key != null && key.equals(k)))) {
                        old = e;
                        break;
                    }
                    ++binCount;
                } while ((e = e.next) != null);
            }
            V oldValue;
            if (old != null && (oldValue = old.value) != null) {
                afterNodeAccess(old);
                return oldValue;
            }
        }
        V v = mappingFunction.apply(key);
        if (v == null) {
            return null;
        } else if (old != null) {
            old.value = v;
            afterNodeAccess(old);
            return v;
        } else if (t != null)
            t.putTreeVal(this, tab, hash, key, v);
        else {
            tab[i] = newNode(hash, key, v, first);
            if (binCount >= TREEIFY_THRESHOLD - 1)
                treeifyBin(tab, hash);
        }
        ++modCount;
        ++size;
        afterNodeInsertion(true);
        return v;
    }

    public V computeIfPresent(K key,
                              BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
        if (remappingFunction == null)
            throw new NullPointerException();
        MyHashMap.Node<K, V> e;
        V oldValue;
        int hash = hash(key);
        if ((e = getNode(hash, key)) != null &&
                (oldValue = e.value) != null) {
            V v = remappingFunction.apply(key, oldValue);
            if (v != null) {
                e.value = v;
                afterNodeAccess(e);
                return v;
            } else
                removeNode(hash, key, null, false, true);
        }
        return null;
    }

    @Override
    public V compute(K key,
                     BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
        if (remappingFunction == null)
            throw new NullPointerException();
        int hash = hash(key);
        MyHashMap.Node<K, V>[] tab;
        MyHashMap.Node<K, V> first;
        int n, i;
        int binCount = 0;
        MyHashMap.TreeNode<K, V> t = null;
        MyHashMap.Node<K, V> old = null;
        if (size > threshold || (tab = table) == null ||
                (n = tab.length) == 0)
            n = (tab = resize()).length;
        if ((first = tab[i = (n - 1) & hash]) != null) {
            if (first instanceof MyHashMap.TreeNode)
                old = (t = (MyHashMap.TreeNode<K, V>) first).getTreeNode(hash, key);
            else {
                MyHashMap.Node<K, V> e = first;
                K k;
                do {
                    if (e.hash == hash &&
                            ((k = e.key) == key || (key != null && key.equals(k)))) {
                        old = e;
                        break;
                    }
                    ++binCount;
                } while ((e = e.next) != null);
            }
        }
        V oldValue = (old == null) ? null : old.value;
        V v = remappingFunction.apply(key, oldValue);
        if (old != null) {
            if (v != null) {
                old.value = v;
                afterNodeAccess(old);
            } else
                removeNode(hash, key, null, false, true);
        } else if (v != null) {
            if (t != null)
                t.putTreeVal(this, tab, hash, key, v);
            else {
                tab[i] = newNode(hash, key, v, first);
                if (binCount >= TREEIFY_THRESHOLD - 1)
                    treeifyBin(tab, hash);
            }
            ++modCount;
            ++size;
            afterNodeInsertion(true);
        }
        return v;
    }

    @Override
    public V merge(K key, V value,
                   BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
        if (value == null)
            throw new NullPointerException();
        if (remappingFunction == null)
            throw new NullPointerException();
        int hash = hash(key);
        MyHashMap.Node<K, V>[] tab;
        MyHashMap.Node<K, V> first;
        int n, i;
        int binCount = 0;
        MyHashMap.TreeNode<K, V> t = null;
        MyHashMap.Node<K, V> old = null;
        if (size > threshold || (tab = table) == null ||
                (n = tab.length) == 0)
            n = (tab = resize()).length;
        if ((first = tab[i = (n - 1) & hash]) != null) {
            if (first instanceof MyHashMap.TreeNode)
                old = (t = (MyHashMap.TreeNode<K, V>) first).getTreeNode(hash, key);
            else {
                MyHashMap.Node<K, V> e = first;
                K k;
                do {
                    if (e.hash == hash &&
                            ((k = e.key) == key || (key != null && key.equals(k)))) {
                        old = e;
                        break;
                    }
                    ++binCount;
                } while ((e = e.next) != null);
            }
        }
        if (old != null) {
            V v;
            if (old.value != null)
                v = remappingFunction.apply(old.value, value);
            else
                v = value;
            if (v != null) {
                old.value = v;
                afterNodeAccess(old);
            } else
                removeNode(hash, key, null, false, true);
            return v;
        }
        if (value != null) {
            if (t != null)
                t.putTreeVal(this, tab, hash, key, value);
            else {
                tab[i] = newNode(hash, key, value, first);
                if (binCount >= TREEIFY_THRESHOLD - 1)
                    treeifyBin(tab, hash);
            }
            ++modCount;
            ++size;
            afterNodeInsertion(true);
        }
        return value;
    }

    @Override
    public void forEach(BiConsumer<? super K, ? super V> action) {
        MyHashMap.Node<K, V>[] tab;
        if (action == null)
            throw new NullPointerException();
        if (size > 0 && (tab = table) != null) {
            int mc = modCount;
            for (int i = 0; i < tab.length; ++i) {
                for (MyHashMap.Node<K, V> e = tab[i]; e != null; e = e.next)
                    action.accept(e.key, e.value);
            }
            if (modCount != mc)
                throw new ConcurrentModificationException();
        }
    }

    @Override
    public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
        MyHashMap.Node<K, V>[] tab;
        if (function == null)
            throw new NullPointerException();
        if (size > 0 && (tab = table) != null) {
            int mc = modCount;
            for (int i = 0; i < tab.length; ++i) {
                for (MyHashMap.Node<K, V> e = tab[i]; e != null; e = e.next) {
                    e.value = function.apply(e.key, e.value);
                }
            }
            if (modCount != mc)
                throw new ConcurrentModificationException();
        }
    }

    /* ------------------------------------------------------------ */
    // Cloning and serialization

    @SuppressWarnings("unchecked")
    @Override
    public Object clone() {
        MyHashMap<K, V> result;
        try {
            result = (MyHashMap<K, V>) super.clone();
        } catch (CloneNotSupportedException e) {
            // this shouldn't happen, since we are Cloneable
            throw new InternalError(e);
        }
        result.reinitialize();
        result.putMapEntries(this, false);
        return result;
    }

    // These methods are also used when serializing HashSets
    final float loadFactor() {
        return loadFactor;
    }

    final int capacity() {
        return (table != null) ? table.length :
                (threshold > 0) ? threshold :
                        DEFAULT_INITIAL_CAPACITY;
    }

    private void writeObject(java.io.ObjectOutputStream s)
            throws IOException {
        int buckets = capacity();
        // Write out the threshold, loadfactor, and any hidden stuff
        s.defaultWriteObject();
        s.writeInt(buckets);
        s.writeInt(size);
        internalWriteEntries(s);
    }

    /**
     * Reconstitute the {@code HashMap} instance from a stream (i.e.,
     * deserialize it).
     */
    private void readObject(java.io.ObjectInputStream s)
            throws IOException, ClassNotFoundException {
        // Read in the threshold (ignored), loadfactor, and any hidden stuff
        s.defaultReadObject();
        reinitialize();
        if (loadFactor <= 0 || Float.isNaN(loadFactor))
            throw new InvalidObjectException("Illegal load factor: " +
                    loadFactor);
        s.readInt();                // Read and ignore number of buckets
        int mappings = s.readInt(); // Read number of mappings (size)
        if (mappings < 0)
            throw new InvalidObjectException("Illegal mappings count: " +
                    mappings);
        else if (mappings > 0) { // (if zero, use defaults)
            // Size the table using given load factor only if within
            // range of 0.25...4.0
            float lf = Math.min(Math.max(0.25f, loadFactor), 4.0f);
            float fc = (float) mappings / lf + 1.0f;
            int cap = ((fc < DEFAULT_INITIAL_CAPACITY) ?
                    DEFAULT_INITIAL_CAPACITY :
                    (fc >= MAXIMUM_CAPACITY) ?
                            MAXIMUM_CAPACITY :
                            tableSizeFor((int) fc));
            float ft = (float) cap * lf;
            threshold = ((cap < MAXIMUM_CAPACITY && ft < MAXIMUM_CAPACITY) ?
                    (int) ft : Integer.MAX_VALUE);
            @SuppressWarnings({"rawtypes", "unchecked"})
            MyHashMap.Node<K, V>[] tab = (MyHashMap.Node<K, V>[]) new MyHashMap.Node[cap];
            table = tab;

            // Read the keys and values, and put the mappings in the HashMap
            for (int i = 0; i < mappings; i++) {
                @SuppressWarnings("unchecked")
                K key = (K) s.readObject();
                @SuppressWarnings("unchecked")
                V value = (V) s.readObject();
                putVal(hash(key), key, value, false, false);
            }
        }
    }

    /* ------------------------------------------------------------ */
    // iterators

    abstract class HashIterator {
        MyHashMap.Node<K, V> next;        // next entry to return
        MyHashMap.Node<K, V> current;     // current entry
        int expectedModCount;  // for fast-fail
        int index;             // current slot

        HashIterator() {
            expectedModCount = modCount;
            MyHashMap.Node<K, V>[] t = table;
            current = next = null;
            index = 0;
            if (t != null && size > 0) { // advance to first entry
                do {
                } while (index < t.length && (next = t[index++]) == null);
            }
        }

        public final boolean hasNext() {
            return next != null;
        }

        final MyHashMap.Node<K, V> nextNode() {
            MyHashMap.Node<K, V>[] t;
            MyHashMap.Node<K, V> e = next;
            if (modCount != expectedModCount)
                throw new ConcurrentModificationException();
            if (e == null)
                throw new NoSuchElementException();
            if ((next = (current = e).next) == null && (t = table) != null) {
                do {
                } while (index < t.length && (next = t[index++]) == null);
            }
            return e;
        }

        public final void remove() {
            MyHashMap.Node<K, V> p = current;
            if (p == null)
                throw new IllegalStateException();
            if (modCount != expectedModCount)
                throw new ConcurrentModificationException();
            current = null;
            K key = p.key;
            removeNode(hash(key), key, null, false, false);
            expectedModCount = modCount;
        }
    }

    final class KeyIterator extends MyHashMap.HashIterator
            implements Iterator<K> {
        public final K next() {
            return null;
        }
    }

    final class ValueIterator extends MyHashMap.HashIterator
            implements Iterator<V> {
        public final V next() {
            return null;
        }
    }

    final class EntryIterator extends MyHashMap.HashIterator
            implements Iterator<Map.Entry<K, V>> {
        public final Map.Entry<K, V> next() {
            return nextNode();
        }
    }

    /* ------------------------------------------------------------ */
    // spliterators

    static class MyHashMapSpliterator<K, V> {
        final MyHashMap<K, V> map;
        MyHashMap.Node<K, V> current;          // current node
        int index;                  // current index, modified on advance/split
        int fence;                  // one past last index
        int est;                    // size estimate
        int expectedModCount;       // for comodification checks

        MyHashMapSpliterator(MyHashMap<K, V> m, int origin,
                             int fence, int est,
                             int expectedModCount) {
            this.map = m;
            this.index = origin;
            this.fence = fence;
            this.est = est;
            this.expectedModCount = expectedModCount;
        }

        final int getFence() { // initialize fence and size on first use
            int hi;
            if ((hi = fence) < 0) {
                MyHashMap<K, V> m = map;
                est = m.size;
                expectedModCount = m.modCount;
                MyHashMap.Node<K, V>[] tab = m.table;
                hi = fence = (tab == null) ? 0 : tab.length;
            }
            return hi;
        }

        public final long estimateSize() {
            getFence(); // force init
            return (long) est;
        }
    }

    static final class KeySpliterator<K, V>
            extends MyHashMap.MyHashMapSpliterator<K, V>
            implements Spliterator<K> {
        KeySpliterator(MyHashMap<K, V> m, int origin, int fence, int est,
                       int expectedModCount) {
            super(m, origin, fence, est, expectedModCount);
        }

        public MyHashMap.KeySpliterator<K, V> trySplit() {
            int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
            return (lo >= mid || current != null) ? null :
                    new MyHashMap.KeySpliterator<>(map, lo, index = mid, est >>>= 1,
                            expectedModCount);
        }

        public void forEachRemaining(Consumer<? super K> action) {
            int i, hi, mc;
            if (action == null)
                throw new NullPointerException();
            MyHashMap<K, V> m = map;
            MyHashMap.Node<K, V>[] tab = m.table;
            if ((hi = fence) < 0) {
                mc = expectedModCount = m.modCount;
                hi = fence = (tab == null) ? 0 : tab.length;
            } else
                mc = expectedModCount;
            if (tab != null && tab.length >= hi &&
                    (i = index) >= 0 && (i < (index = hi) || current != null)) {
                MyHashMap.Node<K, V> p = current;
                current = null;
                do {
                    if (p == null)
                        p = tab[i++];
                    else {
                        action.accept(p.key);
                        p = p.next;
                    }
                } while (p != null || i < hi);
                if (m.modCount != mc)
                    throw new ConcurrentModificationException();
            }
        }

        public boolean tryAdvance(Consumer<? super K> action) {
            int hi;
            if (action == null)
                throw new NullPointerException();
            MyHashMap.Node<K, V>[] tab = map.table;
            if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
                while (current != null || index < hi) {
                    if (current == null)
                        current = tab[index++];
                    else {
                        K k = current.key;
                        current = current.next;
                        action.accept(k);
                        if (map.modCount != expectedModCount)
                            throw new ConcurrentModificationException();
                        return true;
                    }
                }
            }
            return false;
        }

        public int characteristics() {
            return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
                    Spliterator.DISTINCT;
        }
    }

    static final class ValueSpliterator<K, V>
            extends MyHashMap.MyHashMapSpliterator<K, V>
            implements Spliterator<V> {
        ValueSpliterator(MyHashMap<K, V> m, int origin, int fence, int est,
                         int expectedModCount) {
            super(m, origin, fence, est, expectedModCount);
        }

        public MyHashMap.ValueSpliterator<K, V> trySplit() {
            int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
            return (lo >= mid || current != null) ? null :
                    new MyHashMap.ValueSpliterator<>(map, lo, index = mid, est >>>= 1,
                            expectedModCount);
        }

        public void forEachRemaining(Consumer<? super V> action) {
            int i, hi, mc;
            if (action == null)
                throw new NullPointerException();
            MyHashMap<K, V> m = map;
            MyHashMap.Node<K, V>[] tab = m.table;
            if ((hi = fence) < 0) {
                mc = expectedModCount = m.modCount;
                hi = fence = (tab == null) ? 0 : tab.length;
            } else
                mc = expectedModCount;
            if (tab != null && tab.length >= hi &&
                    (i = index) >= 0 && (i < (index = hi) || current != null)) {
                MyHashMap.Node<K, V> p = current;
                current = null;
                do {
                    if (p == null)
                        p = tab[i++];
                    else {
                        action.accept(p.value);
                        p = p.next;
                    }
                } while (p != null || i < hi);
                if (m.modCount != mc)
                    throw new ConcurrentModificationException();
            }
        }

        public boolean tryAdvance(Consumer<? super V> action) {
            int hi;
            if (action == null)
                throw new NullPointerException();
            MyHashMap.Node<K, V>[] tab = map.table;
            if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
                while (current != null || index < hi) {
                    if (current == null)
                        current = tab[index++];
                    else {
                        V v = current.value;
                        current = current.next;
                        action.accept(v);
                        if (map.modCount != expectedModCount)
                            throw new ConcurrentModificationException();
                        return true;
                    }
                }
            }
            return false;
        }

        public int characteristics() {
            return (fence < 0 || est == map.size ? Spliterator.SIZED : 0);
        }
    }

    static final class EntrySpliterator<K, V>
            extends MyHashMap.MyHashMapSpliterator<K, V>
            implements Spliterator<Map.Entry<K, V>> {
        EntrySpliterator(MyHashMap<K, V> m, int origin, int fence, int est,
                         int expectedModCount) {
            super(m, origin, fence, est, expectedModCount);
        }

        public MyHashMap.EntrySpliterator<K, V> trySplit() {
            int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
            return (lo >= mid || current != null) ? null :
                    new MyHashMap.EntrySpliterator<>(map, lo, index = mid, est >>>= 1,
                            expectedModCount);
        }

        public void forEachRemaining(Consumer<? super Map.Entry<K, V>> action) {
            int i, hi, mc;
            if (action == null)
                throw new NullPointerException();
            MyHashMap<K, V> m = map;
            MyHashMap.Node<K, V>[] tab = m.table;
            if ((hi = fence) < 0) {
                mc = expectedModCount = m.modCount;
                hi = fence = (tab == null) ? 0 : tab.length;
            } else
                mc = expectedModCount;
            if (tab != null && tab.length >= hi &&
                    (i = index) >= 0 && (i < (index = hi) || current != null)) {
                MyHashMap.Node<K, V> p = current;
                current = null;
                do {
                    if (p == null)
                        p = tab[i++];
                    else {
                        action.accept(p);
                        p = p.next;
                    }
                } while (p != null || i < hi);
                if (m.modCount != mc)
                    throw new ConcurrentModificationException();
            }
        }

        public boolean tryAdvance(Consumer<? super Map.Entry<K, V>> action) {
            int hi;
            if (action == null)
                throw new NullPointerException();
            MyHashMap.Node<K, V>[] tab = map.table;
            if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
                while (current != null || index < hi) {
                    if (current == null)
                        current = tab[index++];
                    else {
                        MyHashMap.Node<K, V> e = current;
                        current = current.next;
                        action.accept(e);
                        if (map.modCount != expectedModCount)
                            throw new ConcurrentModificationException();
                        return true;
                    }
                }
            }
            return false;
        }

        public int characteristics() {
            return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
                    Spliterator.DISTINCT;
        }
    }


    // Create a regular (non-tree) node
    MyHashMap.Node<K, V> newNode(int hash, K key, V value, MyHashMap.Node<K, V> next) {
        return new MyHashMap.Node(hash, key, value, next);
    }

    // For conversion from TreeNodes to plain nodes
    MyHashMap.Node<K, V> replacementNode(MyHashMap.Node<K, V> p, MyHashMap.Node<K, V> next) {
        return new MyHashMap.Node(p.hash, p.key, p.value, next);
    }

    // Create a tree bin node
    MyHashMap.TreeNode<K, V> newTreeNode(int hash, K key, V value, MyHashMap.Node<K, V> next) {
        return new MyHashMap.TreeNode<>(hash, key, value, next);
    }

    // For treeifyBin
    MyHashMap.TreeNode<K, V> replacementTreeNode(MyHashMap.Node<K, V> p, MyHashMap.Node<K, V> next) {
        return new MyHashMap.TreeNode<>(p.hash, p.key, p.value, next);
    }

    /**
     * Reset to initial default state.  Called by clone and readObject.
     */
    void reinitialize() {
        table = null;
        entrySet = null;
        keySet = null;
        values = null;
        modCount = 0;
        threshold = 0;
        size = 0;
    }

    // Callbacks to allow LinkedHashMap post-actions
    void afterNodeAccess(MyHashMap.Node<K, V> p) {
    }

    void afterNodeInsertion(boolean evict) {
    }

    void afterNodeRemoval(MyHashMap.Node<K, V> p) {
    }

    // Called only from writeObject, to ensure compatible ordering.
    void internalWriteEntries(java.io.ObjectOutputStream s) throws IOException {
        MyHashMap.Node<K, V>[] tab;
        if (size > 0 && (tab = table) != null) {
            for (int i = 0; i < tab.length; ++i) {
                for (MyHashMap.Node<K, V> e = tab[i]; e != null; e = e.next) {
                    s.writeObject(e.key);
                    s.writeObject(e.value);
                }
            }
        }
    }

    /* ------------------------------------------------------------ */
    // Tree bins

    /**
     * Entry for Tree bins. Extends LinkedHashMap.Entry (which in turn
     * extends Node) so can be used as extension of either regular or
     * linked node.
     */
    static class Entry<K, V> extends MyHashMap.Node<K, V> {
        Entry<K, V> before, after;// before, after用来记录entry对象的前一个和后一个元素

        Entry(int hash, K key, V value, Node<K, V> next) {
            super(hash, key, value, next);
        }
    }

    static final class TreeNode<K, V> extends Entry<K, V> {
        MyHashMap.TreeNode<K, V> parent;  // red-black tree links
        MyHashMap.TreeNode<K, V> left;
        MyHashMap.TreeNode<K, V> right;
        MyHashMap.TreeNode<K, V> prev;    // needed to unlink next upon deletion
        boolean red;

        TreeNode(int hash, K key, V val, MyHashMap.Node<K, V> next) {
            super(hash, key, val, next);
        }

        /**
         * Returns root of tree containing this node.
         */
        final MyHashMap.TreeNode<K, V> root() {
            for (MyHashMap.TreeNode<K, V> r = this, p; ; ) {
                if ((p = r.parent) == null)
                    return r;
                r = p;
            }
        }

        /**
         * Ensures that the given root is the first node of its bin.
         */
        static <K, V> void moveRootToFront(MyHashMap.Node<K, V>[] tab, MyHashMap.TreeNode<K, V> root) {
            int n;
            if (root != null && tab != null && (n = tab.length) > 0) {
                int index = (n - 1) & root.hash;
                MyHashMap.TreeNode<K, V> first = (MyHashMap.TreeNode<K, V>) tab[index];
                if (root != first) {
                    MyHashMap.Node<K, V> rn;
                    tab[index] = root;
                    MyHashMap.TreeNode<K, V> rp = root.prev;
                    if ((rn = root.next) != null)
                        ((MyHashMap.TreeNode<K, V>) rn).prev = rp;
                    if (rp != null)
                        rp.next = rn;
                    if (first != null)
                        first.prev = root;
                    root.next = first;
                    root.prev = null;
                }
                assert checkInvariants(root);
            }
        }

        final MyHashMap.TreeNode<K, V> find(int h, Object k, Class<?> kc) {
            MyHashMap.TreeNode<K, V> p = this;
            do {
                int ph, dir;
                K pk;
                MyHashMap.TreeNode<K, V> pl = p.left, pr = p.right, q;
                if ((ph = p.hash) > h)
                    p = pl;
                else if (ph < h)
                    p = pr;
                else if ((pk = p.key) == k || (k != null && k.equals(pk)))
                    return p;
                else if (pl == null)
                    p = pr;
                else if (pr == null)
                    p = pl;
                else if ((kc != null ||
                        (kc = comparableClassFor(k)) != null) &&
                        (dir = compareComparables(kc, k, pk)) != 0)
                    p = (dir < 0) ? pl : pr;
                else if ((q = pr.find(h, k, kc)) != null)
                    return q;
                else
                    p = pl;
            } while (p != null);
            return null;
        }

        /**
         * Calls find for root node.
         */
        final MyHashMap.TreeNode<K, V> getTreeNode(int h, Object k) {
            return ((parent != null) ? root() : this).find(h, k, null);
        }

        static int tieBreakOrder(Object a, Object b) {
            int d;
            if (a == null || b == null ||
                    (d = a.getClass().getName().
                            compareTo(b.getClass().getName())) == 0)
                d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
                        -1 : 1);
            return d;
        }

        // 构造红黑树
        final void treeify(MyHashMap.Node<K, V>[] tab) {
            MyHashMap.TreeNode<K, V> root = null;
            for (MyHashMap.TreeNode<K, V> x = this, next; x != null; x = next) {
                next = (MyHashMap.TreeNode<K, V>) x.next;
                x.left = x.right = null;
                if (root == null) {
                    x.parent = null;
                    x.red = false;
                    root = x;
                } else {
                    K k = x.key;
                    int h = x.hash;
                    Class<?> kc = null;
                    for (MyHashMap.TreeNode<K, V> p = root; ; ) {
                        int dir, ph;
                        K pk = p.key;
                        if ((ph = p.hash) > h)
                            dir = -1;
                        else if (ph < h)
                            dir = 1;
                        else if ((kc == null &&
                                (kc = comparableClassFor(k)) == null) ||
                                (dir = compareComparables(kc, k, pk)) == 0)
                            dir = tieBreakOrder(k, pk);

                        MyHashMap.TreeNode<K, V> xp = p;
                        if ((p = (dir <= 0) ? p.left : p.right) == null) {
                            x.parent = xp;
                            if (dir <= 0)
                                xp.left = x;
                            else
                                xp.right = x;
                            root = balanceInsertion(root, x);
                            break;
                        }
                    }
                }
            }
            // 将红黑树的根节点放在原链表的头部节点的位置
            moveRootToFront(tab, root);
        }

        final MyHashMap.Node<K, V> untreeify(MyHashMap<K, V> map) {
            MyHashMap.Node<K, V> hd = null, tl = null;
            for (MyHashMap.Node<K, V> q = this; q != null; q = q.next) {
                MyHashMap.Node<K, V> p = map.replacementNode(q, null);
                if (tl == null)
                    hd = p;
                else
                    tl.next = p;
                tl = p;
            }
            return hd;
        }

        /**
         * Tree version of putVal.
         */
        final MyHashMap.TreeNode<K, V> putTreeVal(MyHashMap<K, V> map, MyHashMap.Node<K, V>[] tab,
                                                  int h, K k, V v) {
            Class<?> kc = null;
            boolean searched = false;
            MyHashMap.TreeNode<K, V> root = (parent != null) ? root() : this;
            for (MyHashMap.TreeNode<K, V> p = root; ; ) {
                int dir, ph;
                K pk;
                if ((ph = p.hash) > h)
                    dir = -1;
                else if (ph < h)
                    dir = 1;
                else if ((pk = p.key) == k || (k != null && k.equals(pk)))
                    return p;
                else if ((kc == null &&
                        (kc = comparableClassFor(k)) == null) ||
                        (dir = compareComparables(kc, k, pk)) == 0) {
                    if (!searched) {
                        MyHashMap.TreeNode<K, V> q, ch;
                        searched = true;
                        if (((ch = p.left) != null &&
                                (q = ch.find(h, k, kc)) != null) ||
                                ((ch = p.right) != null &&
                                        (q = ch.find(h, k, kc)) != null))
                            return q;
                    }
                    dir = tieBreakOrder(k, pk);
                }

                MyHashMap.TreeNode<K, V> xp = p;
                if ((p = (dir <= 0) ? p.left : p.right) == null) {
                    MyHashMap.Node<K, V> xpn = xp.next;
                    MyHashMap.TreeNode<K, V> x = map.newTreeNode(h, k, v, xpn);
                    if (dir <= 0)
                        xp.left = x;
                    else
                        xp.right = x;
                    xp.next = x;
                    x.parent = x.prev = xp;
                    if (xpn != null)
                        ((MyHashMap.TreeNode<K, V>) xpn).prev = x;
                    moveRootToFront(tab, balanceInsertion(root, x));
                    return null;
                }
            }
        }

        final void removeTreeNode(MyHashMap<K, V> map, MyHashMap.Node<K, V>[] tab,
                                  boolean movable) {
            int n;
            if (tab == null || (n = tab.length) == 0)
                return;
            int index = (n - 1) & hash;
            MyHashMap.TreeNode<K, V> first = (MyHashMap.TreeNode<K, V>) tab[index], root = first, rl;
            MyHashMap.TreeNode<K, V> succ = (MyHashMap.TreeNode<K, V>) next, pred = prev;
            if (pred == null)
                tab[index] = first = succ;
            else
                pred.next = succ;
            if (succ != null)
                succ.prev = pred;
            if (first == null)
                return;
            if (root.parent != null)
                root = root.root();
            if (root == null || root.right == null ||
                    (rl = root.left) == null || rl.left == null) {
                tab[index] = first.untreeify(map);  // too small
                return;
            }
            MyHashMap.TreeNode<K, V> p = this, pl = left, pr = right, replacement;
            if (pl != null && pr != null) {
                MyHashMap.TreeNode<K, V> s = pr, sl;
                while ((sl = s.left) != null) // find successor
                    s = sl;
                boolean c = s.red;
                s.red = p.red;
                p.red = c; // swap colors
                MyHashMap.TreeNode<K, V> sr = s.right;
                MyHashMap.TreeNode<K, V> pp = p.parent;
                if (s == pr) { // p was s's direct parent
                    p.parent = s;
                    s.right = p;
                } else {
                    MyHashMap.TreeNode<K, V> sp = s.parent;
                    if ((p.parent = sp) != null) {
                        if (s == sp.left)
                            sp.left = p;
                        else
                            sp.right = p;
                    }
                    if ((s.right = pr) != null)
                        pr.parent = s;
                }
                p.left = null;
                if ((p.right = sr) != null)
                    sr.parent = p;
                if ((s.left = pl) != null)
                    pl.parent = s;
                if ((s.parent = pp) == null)
                    root = s;
                else if (p == pp.left)
                    pp.left = s;
                else
                    pp.right = s;
                if (sr != null)
                    replacement = sr;
                else
                    replacement = p;
            } else if (pl != null)
                replacement = pl;
            else if (pr != null)
                replacement = pr;
            else
                replacement = p;
            if (replacement != p) {
                MyHashMap.TreeNode<K, V> pp = replacement.parent = p.parent;
                if (pp == null)
                    root = replacement;
                else if (p == pp.left)
                    pp.left = replacement;
                else
                    pp.right = replacement;
                p.left = p.right = p.parent = null;
            }

            MyHashMap.TreeNode<K, V> r = p.red ? root : balanceDeletion(root, replacement);

            if (replacement == p) {  // detach
                MyHashMap.TreeNode<K, V> pp = p.parent;
                p.parent = null;
                if (pp != null) {
                    if (p == pp.left)
                        pp.left = null;
                    else if (p == pp.right)
                        pp.right = null;
                }
            }
            if (movable)
                moveRootToFront(tab, r);
        }

        final void split(MyHashMap<K, V> map, MyHashMap.Node<K, V>[] tab, int index, int bit) {
            MyHashMap.TreeNode<K, V> b = this;
            // Relink into lo and hi lists, preserving order
            MyHashMap.TreeNode<K, V> loHead = null, loTail = null;
            MyHashMap.TreeNode<K, V> hiHead = null, hiTail = null;
            int lc = 0, hc = 0;
            for (MyHashMap.TreeNode<K, V> e = b, next; e != null; e = next) {
                next = (MyHashMap.TreeNode<K, V>) e.next;
                e.next = null;
                if ((e.hash & bit) == 0) {
                    if ((e.prev = loTail) == null)
                        loHead = e;
                    else
                        loTail.next = e;
                    loTail = e;
                    ++lc;
                } else {
                    if ((e.prev = hiTail) == null)
                        hiHead = e;
                    else
                        hiTail.next = e;
                    hiTail = e;
                    ++hc;
                }
            }

            if (loHead != null) {
                if (lc <= UNTREEIFY_THRESHOLD)
                    tab[index] = loHead.untreeify(map);
                else {
                    tab[index] = loHead;
                    if (hiHead != null) // (else is already treeified)
                        loHead.treeify(tab);
                }
            }
            if (hiHead != null) {
                if (hc <= UNTREEIFY_THRESHOLD)
                    tab[index + bit] = hiHead.untreeify(map);
                else {
                    tab[index + bit] = hiHead;
                    if (loHead != null)
                        hiHead.treeify(tab);
                }
            }
        }

        /* ------------------------------------------------------------ */
        // Red-black tree methods, all adapted from CLR

        static <K, V> MyHashMap.TreeNode<K, V> rotateLeft(MyHashMap.TreeNode<K, V> root,
                                                          MyHashMap.TreeNode<K, V> p) {
            MyHashMap.TreeNode<K, V> r, pp, rl;
            if (p != null && (r = p.right) != null) {
                if ((rl = p.right = r.left) != null)
                    rl.parent = p;
                if ((pp = r.parent = p.parent) == null)
                    (root = r).red = false;
                else if (pp.left == p)
                    pp.left = r;
                else
                    pp.right = r;
                r.left = p;
                p.parent = r;
            }
            return root;
        }

        static <K, V> MyHashMap.TreeNode<K, V> rotateRight(MyHashMap.TreeNode<K, V> root,
                                                           MyHashMap.TreeNode<K, V> p) {
            MyHashMap.TreeNode<K, V> l, pp, lr;
            if (p != null && (l = p.left) != null) {
                if ((lr = p.left = l.right) != null)
                    lr.parent = p;
                if ((pp = l.parent = p.parent) == null)
                    (root = l).red = false;
                else if (pp.right == p)
                    pp.right = l;
                else
                    pp.left = l;
                l.right = p;
                p.parent = l;
            }
            return root;
        }

        static <K, V> MyHashMap.TreeNode<K, V> balanceInsertion(MyHashMap.TreeNode<K, V> root,
                                                                MyHashMap.TreeNode<K, V> x) {
            x.red = true;
            for (MyHashMap.TreeNode<K, V> xp, xpp, xppl, xppr; ; ) {
                if ((xp = x.parent) == null) {
                    x.red = false;
                    return x;
                } else if (!xp.red || (xpp = xp.parent) == null)
                    return root;
                if (xp == (xppl = xpp.left)) {
                    if ((xppr = xpp.right) != null && xppr.red) {
                        xppr.red = false;
                        xp.red = false;
                        xpp.red = true;
                        x = xpp;
                    } else {
                        if (x == xp.right) {
                            root = rotateLeft(root, x = xp);
                            xpp = (xp = x.parent) == null ? null : xp.parent;
                        }
                        if (xp != null) {
                            xp.red = false;
                            if (xpp != null) {
                                xpp.red = true;
                                root = rotateRight(root, xpp);
                            }
                        }
                    }
                } else {
                    if (xppl != null && xppl.red) {
                        xppl.red = false;
                        xp.red = false;
                        xpp.red = true;
                        x = xpp;
                    } else {
                        if (x == xp.left) {
                            root = rotateRight(root, x = xp);
                            xpp = (xp = x.parent) == null ? null : xp.parent;
                        }
                        if (xp != null) {
                            xp.red = false;
                            if (xpp != null) {
                                xpp.red = true;
                                root = rotateLeft(root, xpp);
                            }
                        }
                    }
                }
            }
        }

        static <K, V> MyHashMap.TreeNode<K, V> balanceDeletion(MyHashMap.TreeNode<K, V> root,
                                                               MyHashMap.TreeNode<K, V> x) {
            for (MyHashMap.TreeNode<K, V> xp, xpl, xpr; ; ) {
                if (x == null || x == root)
                    return root;
                else if ((xp = x.parent) == null) {
                    x.red = false;
                    return x;
                } else if (x.red) {
                    x.red = false;
                    return root;
                } else if ((xpl = xp.left) == x) {
                    if ((xpr = xp.right) != null && xpr.red) {
                        xpr.red = false;
                        xp.red = true;
                        root = rotateLeft(root, xp);
                        xpr = (xp = x.parent) == null ? null : xp.right;
                    }
                    if (xpr == null)
                        x = xp;
                    else {
                        MyHashMap.TreeNode<K, V> sl = xpr.left, sr = xpr.right;
                        if ((sr == null || !sr.red) &&
                                (sl == null || !sl.red)) {
                            xpr.red = true;
                            x = xp;
                        } else {
                            if (sr == null || !sr.red) {
                                if (sl != null)
                                    sl.red = false;
                                xpr.red = true;
                                root = rotateRight(root, xpr);
                                xpr = (xp = x.parent) == null ?
                                        null : xp.right;
                            }
                            if (xpr != null) {
                                xpr.red = (xp == null) ? false : xp.red;
                                if ((sr = xpr.right) != null)
                                    sr.red = false;
                            }
                            if (xp != null) {
                                xp.red = false;
                                root = rotateLeft(root, xp);
                            }
                            x = root;
                        }
                    }
                } else { // symmetric
                    if (xpl != null && xpl.red) {
                        xpl.red = false;
                        xp.red = true;
                        root = rotateRight(root, xp);
                        xpl = (xp = x.parent) == null ? null : xp.left;
                    }
                    if (xpl == null)
                        x = xp;
                    else {
                        MyHashMap.TreeNode<K, V> sl = xpl.left, sr = xpl.right;
                        if ((sl == null || !sl.red) &&
                                (sr == null || !sr.red)) {
                            xpl.red = true;
                            x = xp;
                        } else {
                            if (sl == null || !sl.red) {
                                if (sr != null)
                                    sr.red = false;
                                xpl.red = true;
                                root = rotateLeft(root, xpl);
                                xpl = (xp = x.parent) == null ?
                                        null : xp.left;
                            }
                            if (xpl != null) {
                                xpl.red = (xp == null) ? false : xp.red;
                                if ((sl = xpl.left) != null)
                                    sl.red = false;
                            }
                            if (xp != null) {
                                xp.red = false;
                                root = rotateRight(root, xp);
                            }
                            x = root;
                        }
                    }
                }
            }
        }

        /**
         * Recursive invariant check
         */
        static <K, V> boolean checkInvariants(MyHashMap.TreeNode<K, V> t) {
            MyHashMap.TreeNode<K, V> tp = t.parent, tl = t.left, tr = t.right,
                    tb = t.prev, tn = (MyHashMap.TreeNode<K, V>) t.next;
            if (tb != null && tb.next != t)
                return false;
            if (tn != null && tn.prev != t)
                return false;
            if (tp != null && t != tp.left && t != tp.right)
                return false;
            if (tl != null && (tl.parent != t || tl.hash > t.hash))
                return false;
            if (tr != null && (tr.parent != t || tr.hash < t.hash))
                return false;
            if (t.red && tl != null && tl.red && tr != null && tr.red)
                return false;
            if (tl != null && !checkInvariants(tl))
                return false;
            if (tr != null && !checkInvariants(tr))
                return false;
            return true;
        }
    }

}

测试key类

import java.util.Objects;

public class TestKey {
    private String name;

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        TestKey testKey = (TestKey) o;
        return Objects.equals(name, testKey.name);
    }

    @Override
    public int hashCode() {
        return Objects.hash(name);
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public TestKey() {
    }

    public TestKey(String name) {
        this.name = name;
    }
}

主要是针对putVal()和getNode()部分进行了注释的添加,未完待续…