java中遍历MAP的几种方法

Java代码

   1. Map<String,String> map=new HashMap<String,String>();  
   2. map.put("username", "qq");  
   3. map.put("passWord", "123");  
   4. map.put("userID", "1");  
   5. map.put("email", "[email protected]"); 

Map<String,String> map=new HashMap<String,String>();
map.put("username", "qq");
map.put("passWord", "123");
map.put("userID", "1");
map.put("email", "[email protected]");


第一种用for循环
Java代码

   1. for(Map.Entry<String, String> entry:map.entrySet()){  
   2.      System.out.println(entry.getKey()+"--->"+entry.getValue());  
   3. } 

for(Map.Entry<String, String> entry:map.entrySet()){
          System.out.println(entry.getKey()+"--->"+entry.getValue());
}



第二种用迭代
Java代码

   1. Set set = map.entrySet();       
   2. Iterator i = set.iterator();       
   3. while(i.hasNext()){    
   4.      Map.Entry<String, String> entry1=(Map.Entry<String, String>)i.next();  
   5.      System.out.println(entry1.getKey()+"=="+entry1.getValue());  
   6. } 

Set set = map.entrySet();    
Iterator i = set.iterator();    
while(i.hasNext()){ 
    Map.Entry<String, String> entry1=(Map.Entry<String, String>)i.next();
    System.out.println(entry1.getKey()+"=="+entry1.getValue());
}


用keySet()迭代
Java代码

   1. Iterator it=map.keySet().iterator();  
   2. while(it.hasNext()){  
   3.      String key;  
   4.      String value;  
   5.      key=it.next().toString();  
   6.      value=map.get(key);  
   7.      System.out.println(key+"--"+value);  
   8. } 

Iterator it=map.keySet().iterator();
while(it.hasNext()){
    String key;
    String value;
    key=it.next().toString();
    value=map.get(key);
    System.out.println(key+"--"+value);
}



用entrySet()迭代
Java代码

   1. Iterator it=map.entrySet().iterator();         
   2. System.out.println( map.entrySet().size());  
   3. String key;         
   4. String value;  
   5. while(it.hasNext()){  
   6.         Map.Entry entry = (Map.Entry)it.next();         
   7.         key=entry.getKey().toString();         
   8.         value=entry.getValue().toString();         
   9.         System.out.println(key+"===="+value);                   
  10. }