import java.util.*;
public class Test{
	public static void main(String[] args){
		Map<Integer, String> map = new HashMap<>();
		map.put(1,"a");
		map.put(5,"e");
		map.put(4,"d");
		map.put(3,"c");
		map.put(2,"b");
        //第一种方法，将map集合中的键转为set集合
		Set<Integer> set = map.keySet();
		for(Integer i : set){
			System.out.println(i + "=" + map.get(i));
		}
		System.out.println("---------");
        //第二种方法：将map集合转为set集合
		Set<Map.Entry<Integer, String>> set2 = map.entrySet();
		Iterator<Map.Entry<Integer, String>> it = set2.iterator();
		while(it.hasNext()){
			System.out.println(it.next());
		}
	}
}