HashMap集合存储学生对象并遍历

package package5;
//创建一个HashMap集合，键是学号(String)，值是学生对象(Student)。存储三个键值对元素，并遍历
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

public class HashMapDemo {
    public static void main(String[] args) {
        //创建HashMap集合对象
        HashMap<String,Student> hashMap =new HashMap<>();
        //创建学生对象
        Student s1 =new Student("张三",21);
        Student s2 =new Student("李四",22);
        Student s3 =new Student("王五",23);
        //将学生对象存储到集合中
        hashMap.put("h001",s1);
        hashMap.put("h002",s2);
        hashMap.put("h003",s3);
        //遍历集合方式1：键找值
        //获取所有的键的集合
        Set<String> keySet = hashMap.keySet();
        for(String key:keySet){
            Student value = hashMap.get(key);
            System.out.println(key+","+value.getName()+", "+value.getAge());
        }
        //方法2：键值对对象找键和值
        //获取所有键值对对象的集合
        Set<Map.Entry<String, Student>> entries = hashMap.entrySet();
        for(Map.Entry<String, Student> s:entries){
            String key = s.getKey();
            Student value = s.getValue();
            System.out.println(key+","+value.getName()+", "+value.getAge());
        }
    }
}

运行结果：

h001,张三, 21
h002,李四, 22
h003,王五, 23