package test;

import java.util.HashMap;

import java.util.Iterator;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Map.Entry;

import java.util.Set;

public class test6 {

	public static void main(String[] args) {

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

		map.put("a", 1);

		map.put("b", 2);

		map.put("c", 3);

		map.put("d", 4);

//		 Map map=new HashMap();

//         map.put("a", "aaa");

//         map.put("b", "bbb");

//         map.put("c", "ccc");

//         map.put("d", "ddd");    

		//hashMap遍历方法1

         Iterator<String> iterator = map.keySet().iterator();

         while (iterator.hasNext()) {

          Object key = iterator.next();

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

         }

         //遍历方法2

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

         Iterator<Map.Entry<String, Integer>> it=set.iterator();

         while(it.hasNext()){

       	  //System.out.println(list.get(0) );

        	 Map.Entry<String, Integer> e=it.next();

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

         }

          System.out.println(map.containsValue(1) );

          System.out.println(map.containsKey("a") );

          System.out.println(map.size() );

          System.out.println(map.remove("a") );

          System.out.println(map.size() );

          System.out.println(map.containsKey("a") );

          System.out.println(map.containsValue(1) );  

          //ArrayList <Integer> list =(ArrayList<Integer>)map.values();

          //上面会出现异常，因为map.values()返回的是一个Collection<Integer>对象，可用下面的方法解决

          ArrayList <Integer> list =new ArrayList<Integer>(map.values());

          Iterator <Integer>ite=list.iterator();

          while(ite.hasNext()){

        	  //System.out.println(list.get(0) );

        	  System.out.println(ite.next() );

          }

          map.clear();

          System.out.println(map.isEmpty() );  

	}

}