复习源码分享——Map集合的便利

package com.atguigu.JavaImportant;

import org.junit.Test;

import java.util.*;

public class MapTest {

@Test

public void Test1(){

HashMap map = new HashMap();

map.put(“111”,“撒旦撒旦”);

map.put(“222”,“牛逼克拉斯”);

map.put(“333”,“小鸟伏特加”);

map.put(“1112”,“撒旦撒旦”);

map.put(232323,“撒旦撒旦”);

//遍历所有的key集：keySet()
/*    Set set = map.keySet();
    Iterator it = set.iterator();
    while (it.hasNext()){
        Object next = it.next();
        System.out.println(next);
    }*/



    //遍历所有的value集：values()；
    Collection values = map.values();
    for (Object cc:values ) {
        System.out.println(cc);
    }


    //遍历所有的key-value：entrySet()；
    //方式一
    Set set1 = map.entrySet();
    Iterator iterator = set1.iterator();
    while (iterator.hasNext()){
        Object next = iterator.next();
        //entrySet集合中的元素都是entry
        Map.Entry entry = (Map.Entry) next;
        System.out.println(entry.getKey()+"---->"+entry.getValue());
    }

    //方式二
    Set set = map.keySet();
    Iterator it = set.iterator();
    while (it.hasNext()){
        Object next = it.next();
        Object o = map.get(next);
        System.out.println(next+"====="+o);
    }
}
           

}