介绍map.entry接口

package test;
import java.util.*;
import java.util.Map.Entry;
public class B {  
    public static void main(String[] args) {   
        Map<Integer,Integer> mm = new HashMap<Integer,Integer>();   
        for(int i=0;i<10;i++)   {
            mm.put(i, i); 
        }   
        for( Entry<Integer, Integer> e : mm.entrySet()) {
            System.out.println("key:"+e.getKey());
            System.out.println("value:"+e.getValue());   
        }   
        for( Iterator<Entry<Integer, Integer>> i = mm.entrySet().iterator(); i.hasNext(); ){    
            Entry<Integer, Integer> e = i.next();
            System.out.println("key:"+e.getKey());
            System.out.println("value:"+e.getValue());
        }   
     }   49 }