hashMap分別獲取所有key和value

import java.util.*;
 
public class Main {
    public static void main(String[] args){
//        Scanner scanner=new Scanner(System.in);//在線筆試
        HashMap<Integer,Integer> map=new HashMap<Integer, Integer>();
        map.put(1,2);
        map.put(2,3);
        map.put(3,4);
        map.put(4,4);
 
 
        //獲取所有key
        Set<Integer> keys=map.keySet();
        Iterator<Integer> iterator1=keys.iterator();
        while (iterator1.hasNext()){
            System.out.print(iterator1.next() +", ");
        }
        System.out.println();
        System.out.println("------------------------");
 
        //獲取所有value
        Collection<Integer> values=map.values();
        Iterator<Integer> iterator2=values.iterator();
        while (iterator2.hasNext()){
            System.out.print(iterator2.next()+", ");
        }
        System.out.println();
        System.out.println("------------------------");
 
        //去除value中重復值,相同值僅僅保留一個
        Set<Integer> valuesSimple=new HashSet<Integer>();
        for(int i:values){
            valuesSimple.add(i);
        }
        Iterator<Integer> iterator3=valuesSimple.iterator();
        while (iterator3.hasNext()){
            System.out.print(iterator3.next()+", ");
        }
    }
}


https://blog.csdn.net/caoxiaohong1005/article/details/78211825