Java

//1: 常规Map.keySet遍历，两次取值
//2：推荐 map.entrySet()，容量大很好
//3、map.entrySet().iterator()遍历
//4、String v : map.values())遍历

import java.util.*;
public class Test{
     public static void main(String[] args) {
      Map map = new HashMap();
      map.put("4", "v1");
      map.put("5", "v2");
      map.put("6", "v3");
      
      //1常规Map.keySet遍历，两次取值
      for (String key : map.keySet()) {
       System.out.println("Map.keySet遍历----key和value：");
       System.out.println("key= "+ key + " and value= " + map.get(key));
      }
      //2：推荐 map.entrySet()，容量大很好
      for (Map.Entry entry : map.entrySet()) {
      	System.out.println("Map.entrySet遍历---key和value");
       	System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
      }
    //3、map.entrySet().iterator()遍历
      System.out.println("entrySet  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());
      }
      //4、String v : map.values())遍历
      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);
      }
     }
}