遍历HashMap的方法

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);

    }

   }

}

}