Java克隆执行深拷贝

示例

要复制嵌套对象，必须执行深层复制，如本示例所示。

import java.util.ArrayList;
import java.util.List;

public class Sheep implements Cloneable {

    private String name;

    private int weight;

    private List<Sheep> children;

    public Sheep(String name, int weight) {
       this.name= name;
       this.weight= weight;
    }

    @Override
    public Object clone() throws CloneNotSupportedException {
        Sheep clone = (Sheep) super.clone();
        if (children != null) {
            // 深拷贝
            List<Sheep> cloneChildren = new ArrayList<>(children.size());
            for (Sheep child : children) {
                cloneChildren.add((Sheep) child.clone());
            }
            clone.setChildren(cloneChildren);
        }
        return clone;
    }

    public List<Sheep> getChildren() {
        return children;
    }

    public void setChildren(List<Sheep> children) {
       this.children= children;
    }

}

import java.util.Arrays;
import java.util.List;

Sheep sheep = new Sheep("Dolly", 20);

Sheep child1 = new Sheep("Child1", 4);
Sheep child2 = new Sheep("Child2", 5);

sheep.setChildren(Arrays.asList(child1, child2));

// 克隆sheep
Sheep dolly =  (Sheep) sheep.clone();
List<Sheep> sheepChildren = sheep.getChildren();
List<Sheep> dollysChildren = dolly.getChildren();
for (int i = 0; i < sheepChildren.size(); i++) {
    // 打印false，两个数组都包含内部对象的副本
    System.out.println(sheepChildren.get(i) == dollysChildren.get(i));
}