java.util.WeakHashMap.putAll() java.util.WeakHashMap.put() java.util.WeakHashMap.remove() 描述 所述putAll(Map<? extends K,? extends V> m) 方法用于所有映射的从指定映射到这个map.These映射复制将替换此地图中有任何键的目前任何映射指定地图。 声明 以下是java.util.WeakHashMap.putAll()方法的声明。 public void putAll(Map<? extends K,? extends V> m) 参数 m - 这是要存储在此映射中的映射。 返回值 NA 异常 NullPointerException - 如果指定的映射为null,则抛出此异常。 实例 以下示例显示了java.util.WeakHashMap.putAll()方法的用法。 package com.tutorialspoint; import java.util.Map; import java.util.WeakHashMap; public class WeakHashMapDemo { public static void main(String[] args) { Map<String, String> weakHashMapOne = new WeakHashMap<String, String>(); Map<String, String> weakHashMapTwo = new WeakHashMap<String, String>(); // put keys and values in the Map System.out.println("Populating two Maps"); weakHashMapOne.put("1", "first"); weakHashMapOne.put("2", "two"); weakHashMapOne.put("3", "three"); weakHashMapTwo.put("1", "1st"); weakHashMapTwo.put("2", "2nd"); weakHashMapTwo.put("3", "3rd"); // checking Map System.out.println("Before - Map 1: "+weakHashMapOne); System.out.println("Before - Map 2: "+weakHashMapTwo); // putting map 2 into map1 weakHashMapOne.putAll(weakHashMapTwo); System.out.println("After - Map 1: "+weakHashMapOne); System.out.println("After - Map 2: "+weakHashMapTwo); } } 让我们编译并运行上面的程序,这将产生以下结果。 Putting values into the Map Before - Map 1: {1=first, 2=two, 3=three} Before - Map 2: {1=1st, 2=2nd, 3=3rd} After - Map 1: {1=1st, 2=2nd, 3=3rd} After - Map 2: {1=1st, 2=2nd, 3=3rd} java.util.WeakHashMap.put() java.util.WeakHashMap.remove()