map的遍历方式（使用Junit测试）

package cn.sdut.lah;

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

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class Demo2 {

	Map map = null;
	@Before
	public void before(){
	    map = new HashMap();//若要按照存入的顺序输出，则使用linkedHashMap
		map.put(1, "唐僧");
		map.put(2, "猪八戒");
		map.put(3, "孙悟空");
	}
	/**
	 * way1: 先获取键集合，由键的到值
	 */
	@Test
	public void test1(){

		//使用迭代器遍历
		Set set = map.keySet();
		Iterator it = set.iterator();
		while(it.hasNext()){
			int key = (int) it.next();
			String value = (String) map.get(key);
			System.out.println(key+": "+value);
		}

	}
	@Test
	public void test11(){

		//使用增强for循环遍历
		for (Object obj:map.keySet()){
			 int key = (int) obj;
			 String value = (String) map.get(key);
			 System.out.println(key+": "+value);
		 }
	}

	/**
	 * way2:先获取键值对集合，从而得到键和值
	 */
	@Test
	public void test2(){

		//使用迭代器遍历
		Set set = map.entrySet();
		Iterator it = set.iterator();
	    while(it.hasNext()){
	    	Map.Entry entry = (Entry) it.next();
	    	int key = (int) entry.getKey();
	    	String value = (String) entry.getValue();
	    	System.out.println(key+": "+value);
	    }
	}

	public void test22(){

		//使用增强for循环遍历
		for (Object obj:map.entrySet()){
			Map.Entry entry = (Entry) obj;
			int key =  (int) entry.getKey();
			String value = (String) entry.getValue();
			System.out.println(key+": "+value);
		}
	}
	@After
	public void after(){
		map = null;
	}

}