java Map 遍历方法

Map map = 
new


 HashMap();

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

    
while


 (it.hasNext()) {

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

        Object key = entry.getKey();

        Object value = entry.getValue();

}

Map map = new HashMap();

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

    while (it.hasNext()) {

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

        Object key = entry.getKey();

        Object value = entry.getValue();

}

JDK1.5中,应用新特性For-Each循环

Map m = 
new


 HashMap();

for


(Object o : map.keySet()){

    map.get(o);

}

Map m = new HashMap();

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

    map.get(o);

}

返回的 set 中的每个元素都是一个 Map.Entry 类型。

private Hashtable<String, String> emails = new Hashtable<String, String>();
  另外 我们可以先把hashMap 转为集合Collection，再迭代输出，不过得到的对象

//方法一: 用entrySet()

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

   
while


(it.hasNext()){

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

    logger.info(
"email-"

 + m.getKey() + 
":"

 + m.getValue());

   }

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

   while(it.hasNext()){

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

    logger.info("email-" + m.getKey() + ":" + m.getValue());

   }

 

   // 方法二：jdk1.5支持，用entrySet()和For-Each循环()

for


 (Map.Entry<String, String> m : emails.entrySet()) {



    logger.info(
"email-"

 + m.getKey() + 
":"

 + m.getValue());

   }

for (Map.Entry<String, String> m : emails.entrySet()) {

   

    logger.info("email-" + m.getKey() + ":" + m.getValue());

   }

 

   // 方法三：用keySet()

Iterator it = emails.keySet().iterator();

  
while


 (it.hasNext()){

   String key;

   key=(String)it.next();

   logger.info(
"email-"

 + key + 
":"

 + emails.get(key));

  }

 Iterator it = emails.keySet().iterator();

   while (it.hasNext()){

    String key;

    key=(String)it.next();

    logger.info("email-" + key + ":" + emails.get(key));

   }

// 方法五：jdk1.5支持，用keySEt()和For-Each循环

for


(Object m: emails.keySet()){

    logger.info(
"email-"

 + m+ 
":"

 + emails.get(m));

   }
      Map    aa    =    
new


    HashMap();
 aa.put(
"tmp1"

,    
new


    Object());
//追加      替换用同样的函数.
aa.remove(
"temp1"

);
//删除
for


    (Iterator    i    =    aa.values().iterator();    i.hasNext();    )    {              Object    temp    =    i.next();      }
 
//遍历

for(Object m: emails.keySet()){

    logger.info("email-" + m+ ":" + emails.get(m));

   }
      Map    aa    =    new    HashMap();     
 aa.put("tmp1",    new    Object());      
//追加      替换用同样的函数.      
aa.remove("temp1");                        
//删除      
for    (Iterator    i    =    aa.values().iterator();    i.hasNext();    )    {              Object    temp    =    i.next();      }         
 //遍历  

   

来个完整的，包含TreeSet的元素内部排序的

public


 
static


 
void


 main(String[] args) {

   ArrayList<String> list = 
new


 ArrayList<String>();

   HashMap<Object,Object> hash = 
new


 HashMap<Object,Object>();

   TreeMap<Object,Object> treeMap = 
new


 TreeMap<Object,Object>();

   list.add(
"a"

);

   list.add(
"b"

);

   list.add(
"c"

);



   hash.put(
3

, 
3

);

   hash.put(
4

, 
4

);

   hash.put(
5

, 
5

);

   hash.put(
6

, 
6

);

   hash.put(
1

, 
1

);

   hash.put(
2

, 
2

);



   treeMap.put(
1

, 
1

);

   treeMap.put(
2

, 
2

);

   treeMap.put(
3

, 
3

);

   treeMap.put(
4

, 
4

);

   treeMap.put(
5

, 
5

);

   treeMap.put(
6

, 
6

);



   
//list遍历

   
for


(String m: list){

    System.out.println(m);

   }

   
// hashmap entrySet() 遍历

   
for


(Map.Entry<Object,Object> m: hash.entrySet()){

    System.out.println(m.getKey()+
"---"

+m.getValue());

   }

   
//hashmap keySet() 遍历

   
for


(Object m: hash.keySet()){

    System.out.println(m+
"---"

+hash.get(m));

   }

   
// treemap keySet()遍历

   
for


(Object m: treeMap.keySet()){

    System.out.println(m+
"---"

+treeMap.get(m));

   }

}