java lt k v gt_void putAll(Map<? extends K,? extends V> m)_Java.util包|WIKI教程

void putAll(Map extends K,? extends V> m)

描述 (Description)

putAll(Map《? extends K,? extends V》 m)方法用于将指定映射中的所有映射复制到此映射。这些映射将替换此映射对当前位于此映射中的任何键的任何映射。指定的地图。

声明 (Declaration)

以下是java.util.WeakHashMap.putAll()方法的声明。public void putAll(Map extends K,? extends V> m)

参数 (Parameters)

m - 这是存储在此映射中的映射。

返回值 (Return Value)

NA

异常 (Exception)

NullPointerException - 如果指定的映射为null，则抛出此异常。

例子 (Example)

以下示例显示了java.util.WeakHashMap.putAll()方法的用法。package com.iowiki;

import java.util.Map;

import java.util.WeakHashMap;

public class WeakHashMapDemo {

public static void main(String[] args) {

Map weakHashMapOne = new WeakHashMap();

Map weakHashMapTwo = new WeakHashMap();

// 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}