java map的两种遍历方式

//得到所有的key值

      Set<String> keySet = map.keySet();

      //根据key值得到value值

      for (String key : keySet) {

        System.out.println(key+":"+map.get(key));

      }

//得到所有的entry

      Set<Entry<String, String>> entrySet = map.entrySet();

      //从entry中得到key和value值

      for (Entry<String, String> entry : entrySet) {

         System.out.println(entry.getKey()+":"+entry.getValue());

      }

MapTest.java

package map;

 

import java.util.HashMap;

import java.util.Map;

import java.util.Map.Entry;

import java.util.Set;

 

import org.junit.BeforeClass;

import org.junit.Test;

 

publicclass MapTest {

  

   private Map map;

  

   @BeforeClass

   publicvoid init(){

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

      map.put("1", "Morris");

      map.put("2", "Jack");

      map.put("3", "Bob");

      map.put("4", "Tom");

   }

 

  

   @Test

   publicvoid traversal1(){

     

      //得到所有的key值

      Set<String> keySet = map.keySet();

      //根据key值得到value值

      for (String key : keySet) {

        System.out.println(key+":"+map.get(key));

      }

   }

  

   @Test

   publicvoid traversal2(){

      //得到所有的entry

      Set<Entry<String, String>> entrySet = map.entrySet();

      //从entry中得到key和value值

      for (Entry<String, String> entry : entrySet) {

         System.out.println(entry.getKey()+":"+entry.getValue());

      }

   }

}