new_weakhash_map.putAll(exist_weakhash_map)

// Java代码示例 putAll()方法
import java.util.*;

public class WeakHashMap_Demo {
    public static void main(String[] args) {

        //创建一个空的WeakHashMap
        Map weak_hash = new WeakHashMap();

        //将字符串值映射到整数键
        weak_hash.put(10, "Geeks");
        weak_hash.put(15, "4");
        weak_hash.put(20, "Geeks");
        weak_hash.put(25, "Welcomes");
        weak_hash.put(30, "You");

        //显示WeakHashMap
        System.out.println("Initial Mappings are: " +
                                                   weak_hash);

        //创建一个新的weakhash map并复制
        Map new_weakhash_map = new WeakHashMap();
        new_weakhash_map.putAll(weak_hash);

        //显示最终的WeakHashMap
        System.out.println("The new map: " +
                                             new_weakhash_map);
    }
}

初始映射：{30 = You，15 = 4，10 = Geeks，25 = Welcomes，20 = Geeks}
新的映射：{15 = 4，30 = You，10 = Geeks，25 = Welcomes，20 = Geeks}

// Java代码示例putAll()方法
import java.util.*;

public class WeakHash_Map_Demo
{
    public static void main(String[] args)
    {

        //创建一个空的WeakHashMap
        Map weak_hash = new WeakHashMap();

        //将整数值映射到字符串键
        weak_hash.put("Geeks", 10);
        weak_hash.put("4", 15);
        weak_hash.put("Geeks", 20);
        weak_hash.put("Welcomes", 25);
        weak_hash.put("You", 30);

        //显示WeakHashMap
        System.out.println("Initial Mappings are: " + weak_hash);

        //创建一个新的weakhash map并复制
        Map new_weakhash_map = new WeakHashMap();
        new_weakhash_map.putAll(weak_hash);

        //显示最终的WeakHashMap
        System.out.println("The new map: " + new_weakhash_map);
    }
}

初始映射：{Welcomes = 25，4 = 15，You = 30，Geeks = 20}
新的映射：{Welcomes = 25，4 = 15，You = 30，Geeks = 20}