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MapBuilder,操作集合工具类

汝弘深
2023-12-01
public class MapBuilder {    /**     * Creates an instance of {@code HashMap}     */    public static <K, V> HashMap<K, V> newHashMap() {        return new HashMap<>();    }    /**     * Returns the empty map.     */    public static <K, V> Map<K, V> of() {        return newHashMap();    }    /**     * Returns map containing a single entry.     */    public static <K, V> Map<K, V> of(K k1, V v1) {        Map<K, V> map = of();        map.put(k1, v1);        return map;    }    /**     * Returns map containing the given entries.     */    public static <K, V> Map<K, V> of(K k1, V v1, K k2, V v2) {        Map<K, V> map = of();        map.put(k1, v1);        map.put(k2, v2);        return map;    }    /**     * Returns map containing the given entries.     */    public static <K, V> Map<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3) {        Map<K, V> map = of();        map.put(k1, v1);        map.put(k2, v2);        map.put(k3, v3);        return map;    }    /**     * Returns map containing the given entries.     */    public static <K, V> Map<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {        Map<K, V> map = of();        map.put(k1, v1);        map.put(k2, v2);        map.put(k3, v3);        map.put(k4, v4);        return map;    }    /**     * Returns map containing the given entries.     */    public static <K, V> Map<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {        Map<K, V> map = of();        map.put(k1, v1);        map.put(k2, v2);        map.put(k3, v3);        map.put(k4, v4);        map.put(k5, v5);        return map;    }    /**     * Returns map containing the given entries.     */    public static <K, V> Map<K, V> of(            K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6) {        Map<K, V> map = of();        map.put(k1, v1);        map.put(k2, v2);        map.put(k3, v3);        map.put(k4, v4);        map.put(k5, v5);        map.put(k6, v6);        return map;    }    /**     * Returns map containing the given entries.     */    public static <K, V> Map<K, V> of(            K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7) {        Map<K, V> map = of();        map.put(k1, v1);        map.put(k2, v2);        map.put(k3, v3);        map.put(k4, v4);        map.put(k5, v5);        map.put(k6, v6);        map.put(k7, v7);        return map;    }    /**     * Returns map containing the given entries.     */    public static <K, V> Builder<K, V> builder() {        return new Builder<>();    }    public static final class Builder<K, V> {        private Map<K, V> map;        private boolean underConstruction;        private Builder() {            map = newHashMap();            underConstruction = true;        }        public Builder<K, V> put(K k, V v) {            if (!underConstruction) {                throw new IllegalStateException("Underlying map has already been built");            }            map.put(k, v);            return this;        }        public Map<K, V> build() {            if (!underConstruction) {                throw new IllegalStateException("Underlying map has already been built");            }            underConstruction = false;            return map;        }    }}

转载于:https://www.cnblogs.com/hengzhou/p/9543597.html

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