map相关方法的学习

package com.weiyi.study.ss;

import com.google.common.collect.Maps;
import org.junit.Test;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;


public class mapTest {
    /**
     * 测试putAll()方法，将一个map集合的元素添加到另一个集合中
     */
    @Test
    public void test(){
        HashMap<String, String> map = Maps.newHashMap();
        HashMap<String, String> map1 = Maps.newHashMap();
        map.put("1","zhangsan");
        map.put("2","lisi");
        map.put("3","wangfu");
        map.put("4","zhaoliu");
        map1.put("5","sunqi");
        map1.put("6","yangba");
        System.out.println("map中的元素有：" + map);
        System.out.println("===============================");
        System.out.println("map1中的元素有：" + map1);
        map.putAll(map1);
        System.out.println("===============================");
        System.out.println("map和map1的元素总和：" + map);
    }

    /**
     * clear(): 清除map中的元素
     */
    @Test
    public void test2(){
        HashMap<String, String> map = Maps.newHashMap();
        map.put("1","zhangsan");
        map.put("2","lisi");
        map.put("3","wangfu");
        map.put("4","zhaoliu");
        System.out.println("调用clear()方法之前" + map);
        map.clear();
        System.out.println("调用clear()方法之后" + map);
    }

    /**
     * containsKey():判断map中是否包含指定的键
     */
    @Test
    public void test3(){
        HashMap<String, String> map = Maps.newHashMap();
        map.put("1","zhangsan");
        map.put("2","lisi");
        map.put("3","wangfu");
        map.put("4","zhaoliu");
        System.out.println("map中是否包含键为1的元素========>" + map.containsKey("1"));
    }

    /**
     * containsValue():判断map中是否包含指定的值
     */
    @Test
    public void test4(){
        HashMap<String, String> map = Maps.newHashMap();
        map.put("1","zhangsan");
        map.put("2","lisi");
        map.put("3","wangfu");
        map.put("4","zhaoliu");
        System.out.println("map中是否包含值为lisi的元素========>" + map.containsValue("lisi"));
    }

    /**
     * entrySet():返回map到一个Set集合中，以map集合中的Key=Value的形式返回到set中
     */
    @Test
    public void test5(){
        HashMap<String, String> map = Maps.newHashMap();
        map.put("1","zhangsan");
        map.put("2","lisi");
        map.put("3","wangfu");
        map.put("4","zhaoliu");
        Set<Map.Entry<String, String>> entrySet = map.entrySet();
        System.out.println(entrySet);
    }

    /**
     * 遍历map
     */
    @Test
    public void test6(){
        HashMap<String, String> map = Maps.newHashMap();
        map.put("1","zhangsan");
        map.put("2","lisi");
        map.put("3","wangfu");
        map.put("4","zhaoliu");
        Set<Map.Entry<String, String>> entrySet = map.entrySet();
        entrySet.stream().forEach(i -> {
            System.out.println("键为====》" + i.getKey() + "值为====》" + i.getValue());
        });
    }

    /**
     *equals() : 判断一个map集合和另一个map集合是否相等（指map集合中的元素是否相等）
     */
    @Test
    public void test7(){
        HashMap<String, String> map = Maps.newHashMap();
        map.put("1","zhangsan");
        map.put("2","lisi");
        HashMap<String, String> map1 = Maps.newHashMap();
        map1.put("1","zhangsan");
        map1.put("2","lisi");
        System.out.println("map和map1是否相等" + map.equals(map1));
    }

    /**
     * keySet():取map中key的集合
     */
    @Test
    public void test8(){
        HashMap<String, String> map = Maps.newHashMap();
        map.put("1","zhangsan");
        map.put("2","lisi");
        map.put("3","wangfu");
        map.put("4","zhaoliu");
        Set<String> keySet = map.keySet();
        System.out.println(keySet);
    }

    /**
     * remove()：删除指定key值的元素
     */
    @Test
    public void test9(){
        HashMap<String, String> map = Maps.newHashMap();
        map.put("1","zhangsan");
        map.put("2","lisi");
        map.put("3","wangfu");
        map.put("4","zhaoliu");
        System.out.println("调用remove()方法之前的map元素的集合=========>" + map);
        map.remove("3");
        System.out.println("调用remove()方法之后的map元素的集合=========>" + map);
    }

    /**
     * 取map集合中的values集合
     */

    @Test
    public void test10(){
        HashMap<String, String> map = Maps.newHashMap();
        map.put("1","zhangsan");
        map.put("2","lisi");
        map.put("3","wangfu");
        map.put("4","zhaoliu");
        map.values().stream().forEach(System.out::println);

    }

}