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;
}

}