JAVA中的Map的基本操作

import java.util.*;
public class bianliMap {
    public static void main(String[] args) {
        Map map = new HashMap();
        map.put("a",1);
        map.put("b",2);
        map.put(3,"c");
        // 遍历所有的键
        Set set = map.keySet();
        System.out.println(set); //[a, b, 3]
        Iterator iterator = set.iterator();
        while (iterator.hasNext()){
            System.out.println(iterator.next());
        }
        // 遍历所有的值
        Collection values = map.values();
        System.out.println(values);//[1, 2, c]
        for (Object obj : values){
            System.out.println(obj);
        }
        // 遍历所有的值
        Set key = map.keySet();
        Iterator iterator1 = key.iterator();
        while (iterator1.hasNext()){
            Object o = iterator1.next();
            Object o1 = map.get(o);
            System.out.println(o1);
        }
        // 遍历所有的key--value,Map.Entery中有getKey()和getValue()方法
        Set set1 = map.entrySet();
        System.out.println(set1); //[a=1, b=2, 3=c]
        Iterator iterator2 = set1.iterator();
        while (iterator2.hasNext()){
            Object next = iterator2.next();
            Map.Entry next1 = (Map.Entry) next;
            System.out.println(next1.getKey()+ "===>"+ next1.getValue());
            System.out.println(next1);
        }
    }
}

本文地址：https://blog.csdn.net/wht1000001000wyw/article/details/110283090