java中Map集合遍历方法

package com.jackey.topic;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import java.util.Set;

//循环遍历map的方法

public class CircleMap {

public static void main(String[] args) {

Map<String, Integer> tempMap = new HashMap<String, Integer>();

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<String, Integer> 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 <String, ArrayList> map = new HashMap <String,

// ArrayList>();

System.out

.println("java 遍历Map <String, ArrayList> map = new HashMap <String, ArrayList>();");

Map<String, ArrayList> map = new HashMap<String, ArrayList>();

Set<String> keys = map.keySet();

Iterator<String> 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");

Map<String, List> mapList = new HashMap<String, List>();

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

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

List<String> values = (List) entry.getValue();

for (String value : values) {

System.out.println(key + " --> " + value);

}

}

}

}