map常用接口

package WangGang01;

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

public class Dome05 {
    public static void main(String[] args) {
        /*
        增加 put(K key, V value)
        删除：clear() remove(Object key)
        修改
        查看entrySet()    get(Object key)  keySet() size() values()
        判断containsKey(Object key)  containsValue(Object value)  equals(Object o)
        isEmpty()


         */
        //创建map集合 特点：无序 唯一
         Map<String,Integer> map = new HashMap<>();
         map.put("lili",411);
         map.put("alili",4511);
         map.put("Balili",456711);
         map.put("lili",456511);
         map.put("qalili",456111);
//     清空    map.clear();
        //   移除  map.remove("alili");
        System.out.println(map.size());
        System.out.println(map);
        System.out.println("------------");
        //keySet就是对集合中的key进行遍历
        Set<String> strings = map.keySet();
        for (String a :strings){
            System.out.println(a);
        }
        System.out.println("------------");
        //values是对集合中的values遍历
        Collection<Integer> values = map.values();
        for (Integer b : values){
            System.out.println(b);
        }
        System.out.println("-------------");
        Set<Map.Entry<String, Integer>> entries = map.entrySet();
        for (Map.Entry<String, Integer> e :entries){
            System.out.println(e.getKey()+"----"+e.getValue());
        }

    }
}