map集合遍历的五种方法

package nc.util.TestClientTools;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import java.util.Set;

/**

* map集合遍历的五种方法

* @FileName: CircleMap.java

* @ClassName: nc.util.TestClientTools.CircleMap

* @Description: TODO(这里用一句话描述这个类的作用)

* @author chenfang

* @email ichenfang163@

* @date 2017-12-11 下午3:54:24

* @version V1.0

*

*/

//循环遍历map的五种方法

publicclass CircleMap {

publicstaticvoid main(String[] args) {

Map tempMap = new HashMap();

tempMap.put("a", 1);

tempMap.put("b", 2);

tempMap.put("c", 3);

// JDK1.4中

// 遍历方法一hashmap entrySet() 遍历

System.out.println("方法一");

Iterator it = tempMap.entrySet().iterator();

while (it.hasNext()) {

Map.Entry entry = (Map.Entry) it.next();

Object key = entry.getKey();

Object value = entry.getValue();

System.out.println("key=" + key + " value=" + value);

}

System.out.println("");

// JDK1.5中,应用新特性For-Each循环

// 遍历方法二

System.out.println("方法二");

for (Map.Entry entry : tempMap.entrySet()) { String key = entry.getKey().toString();

String value = entry.getValue().toString();

System.out.println("key=" + key + " value=" + value);

}

System.out.println("");

// 遍历方法三hashmap keySet() 遍历

System.out.println("方法三");

for (Iterator i = tempMap.keySet().iterator(); i.hasNext();) { Object obj = i.next();

System.out.println(obj);// 循环输出key

System.out.println("key=" + obj + " value=" +

tempMap.get(obj));

}

for (Iterator i = tempMap.values().iterator(); i.hasNext();) { Object obj = i.next();

System.out.println(obj);// 循环输出value

}

System.out.println("");

// 遍历方法四treemap keySet()遍历

System.out.println("方法四");

for (Object o : tempMap.keySet()) {

System.out.println("key="+ o + " value="+ tempMap.get(o));

}

System.out.println("11111");

// java如何遍历Map map = new HashMap

// ArrayList>();

System.out.println("java 遍历Map map = new HashMap();");

Map map = new HashMap();

Set keys = map.keySet();

Iterator iterator = keys.iterator();

while (iterator.hasNext()) {

String key = iterator.next();

ArrayList arrayList = map.get(key);

for (Object o : arrayList) {

System.out.println(o + "遍历过程");

}

}

System.out.println("2222");

// 遍历方法五

Map mapList = new HashMap();

for (Map.Entry entry : mapList.entrySet()) {

String key = entry.getKey().toString();