HashMap的四种遍历方式

package com.xt.map;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

public class HashMapTest {

    public static void main(String[] args) {

        Map<Integer,Student> students=new HashMap<>();
        students.put(1, new Student("111"));

        Set<Integer> Keys=students.keySet();
        //1
        for (Integer key : Keys) {
            System.out.println(students.get(key));
        }
        //2
        Iterator<Integer> iterator=Keys.iterator();
        while(iterator.hasNext()) {
            System.out.println(students.get(iterator.next()));
        }
        
        Set<Entry<Integer,Student>> entrys = students.entrySet();
        //3
        for (Entry<Integer, Student> entry : entrys) {
            System.out.println(entry.getValue());
        }
        //4
        Iterator<Entry<Integer, Student>> iterator1=entrys.iterator();
        while(iterator1.hasNext()) {
            System.out.println(iterator1.next().getValue());
        }
    }
}