Java TreeMap putAll()方法

java.util.TreeMap.putAll() 用于将所有键值对从一个Map复制到另一个Map。

1 语法

public void putAll(Map<? extends K,? extends V> map)

2 参数

map：这是要存储在此映射中的映射。

3 返回值

无

4 示例 

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * java.util.TreeMap.putAll()方法的例子
 */
import java.util.*;

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

        // creating tree maps
        TreeMap<Integer, String> treemap = new TreeMap<Integer, String>();
        TreeMap<Integer, String> treemap_putall = new TreeMap<Integer, String>();

        // populating tree map
        treemap.put(2, "two");
        treemap.put(1, "one");
        treemap.put(3, "three");
        treemap.put(6, "six");
        treemap.put(5, "five");

        treemap_putall.put(1, "111");
        treemap_putall.put(2, "222");
        treemap_putall.put(7, "777");

        System.out.println("Value before modification: "+ treemap);

        // Putting 2nd map in 1st map
        treemap.putAll(treemap_putall);

        System.out.println("Value after modification: "+ treemap);
    }
}

输出结果为：

Value before modification: {1=one, 2=two, 3=three, 5=five, 6=six}
Value after modification: {1=111, 2=222, 3=three, 5=five, 6=six, 7=777}