Map 就是用来存储 “键(key)-值(value)对”,Map 类中存储的“键值对”通过键来标识，所以键值对不能重复,
Map 接口的实现类有HashMap, TreeMap, HashTable,  Preperties等

package com.jianshun;

import java.util.HashMap;
import java.util.Map;

/**
 * 测试HashMap的使用
 * @author Administrator
 *
 */
public class TextMap {

	public static void main(String[] args) {
		
		Map<Integer, String> m1 = new HashMap<Integer, String>();
		
		m1.put(1, "one");
		m1.put(2, "two");
		m1.put(3, "three");
		
		System.out.println(m1);
		System.out.println(m1.get(1));;
		System.out.println(m1.size());
		System.out.println(m1.containsKey(1));
		System.out.println(m1.containsValue("three"));
		
		Map<Integer, String> m2 = new HashMap<Integer, String>();
		m2.put(4, "四");
		m2.put(5, "五");
		
		m1.putAll(m2);
		System.out.println(m1);
		
		//map中键不能重复,如果重复（根据equals判断），则新的覆盖旧的
		m1.put(3, "三");
		System.out.println(m1);
	}
	
}