遍历Map的几种方式

Posted 2021-12-18 java-h

Java代码  

    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  

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

 

第二种用迭代

Java代码  

    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  

   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 

        Iterator it=map.entrySet().iterator();         
        System.out.println( map.entrySet().size());  
        String key;         
        String value;  
        while(it.hasNext())  
               Map.Entry entry = (Map.Entry)it.next();         
               key=entry.getKey().toString();         
               value=entry.getValue().toString();         
               System.out.println(key+"===="+value);                   
         


 　　  for (Map.Entry<String, String> entry : map.entrySet()) 
        　　System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());