java中遍历MAP的几种方法 

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", "qq@qq.com");   

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

map.put("username", "qq"); 

map.put("passWord", "123"); 

map.put("userID", "1"); 

map.put("email", "qq@qq.com"); 

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);    

}   

第三种用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);                     

}