java学习之----map的使用

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

/**
 * This program tests the Employee class.
 * @version 1.12 2015-05-08
 * @author Cay Horstmann
 */
public class hello
{
    public static void main(String[] args)
    {
        Map<String, String> mymap = new HashMap<String, String>();
        String key ;
        String value;
        for(int i=0; i<10; i++)
        {
            key = "" + i;
            value = "value";
            mymap.put(key, value);
        }

        //方法一
        for(Map.Entry<String, String> entry :  mymap.entrySet())
        {
            System.out.println("key=" + entry.getKey() + " value=" + entry.getValue());
        }

        //方法二
        for(String key1 : mymap.keySet())
        {
            System.out.println("key=" + key1);
        }

        for (String value1 : mymap.values())
        {
            System.out.println("value=" + value1);
        }

        //方法三
        Iterator<Map.Entry<String, String>> entryIterator = mymap.entrySet().iterator();
        while(entryIterator.hasNext())
        {
            Map.Entry<String, String> entry = entryIterator.next();
            System.out.println("key=" + entry.getKey() + " value=" + entry.getValue());
        }

        //方法四
        for (String key1 : mymap.keySet()) {

            String value1 = mymap.get(key1);

            System.out.println("Key = " + key1 + ", Value = " + value1);

        }
    }
}

使用实例

import  java.util.*;

/**
 * Created by chenxun on 2017/5/23.
 */
public class test
{
    public static void main( String args[] )
    {
        HashMap<Integer, String> map = new HashMap<Integer, String>();
        map.put(3, "chenxun1");
        map.put(1, "chenxun2");
        map.put(2, "chenxun3");
        map.put(8, "chenxun4");
        map.put(6, "chenxun5");

        int size = map.size();
        Iterator keyValuePairs = map.entrySet().iterator();
        for(int i=0; i<size; i++)
        {
            Map.Entry entry = (Map.Entry) keyValuePairs.next();
            Integer key = (Integer) entry.getKey();
            String value = (String) entry.getValue();
            System.out.println("key=" + entry.getKey() + " value=" + entry.getValue());
            System.out.println("key=" + key + " value=" + value);
        }
    }
}