Map循环的几种方法

public static void main(String[] args) {

  Map map = new HashMap();  
  map.put("1", "value1");  
  map.put("2", "value2");  
  map.put("3", "value3");  

  //第一种：普遍使用，二次取值  
  System.out.println("通过Map.keySet遍历key和value：");  
  for (String key : map.keySet()) {  
   System.out.println("key= "+ key + " and value= " + map.get(key));  
  }  

  //第二种  
  System.out.println("通过Map.entrySet使用iterator遍历key和value：");  
  Iterator> it = map.entrySet().iterator();  
  while (it.hasNext()) {  
   Map.Entry entry = it.next();  
   System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());  
  }  

  //第三种：推荐，尤其是容量大时  
  System.out.println("通过Map.entrySet遍历key和value");  
  for (Map.Entry entry : map.entrySet()) {  
   System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());  
  }  

  //第四种  
  System.out.println("通过Map.values()遍历所有的value，但不能遍历key");  
  for (String v : map.values()) {  
   System.out.println("value= " + v);  
  }  
 }

  //第五种
  Map testMap = new HashMap();
    testMap.put("1", "test1");
    testMap.put("2", "test2");
    testMap.put("3", "test3");
    System.out.println(testMap);
    // 获取Map的values
    Collection testCollection = testMap.values();
    System.out.println(testCollection);
    for (String temp : testCollection) {
        System.out.println("temp:" + temp);
    }