###最常用,在键值都需要时使用。

Map
    
      map = new HashMap
     
      (); for (Map.Entry
      
        entry : map.entrySet()) {   System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue()); }复制代码
      
     
    

###在for-each循环中遍历keys或values。

Map
    
      map = new HashMap
     
      (); //遍历map中的键 for (Integer key : map.keySet()) {   System.out.println("Key = " + key); } //遍历map中的值 for (Integer value : map.values()) {   System.out.println("Value = " + value); }复制代码
     
    

###使用Iterator遍历

Map
    
      map = new HashMap
     
      (); Iterator
      
       
        > entries = map.entrySet().iterator(); while (entries.hasNext()) {   Map.Entry
        
          entry = entries.next();   System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue()); }复制代码
        
       
      
     
    

Map map = new HashMap(); Iterator entries = map.entrySet().iterator(); while (entries.hasNext()) {   Map.Entry entry = (Map.Entry) entries.next();   Integer key = (Integer)entry.getKey();   Integer value = (Integer)entry.getValue();   System.out.println("Key = " + key + ", Value = " + value); }复制代码

###通过键找值遍历（效率低）

Map
    
      map = new HashMap
     
      (); for (Integer key : map.keySet()) {   Integer value = map.get(key);   System.out.println("Key = " + key + ", Value = " + value);复制代码