Java HashMap嵌套HashMap的实现

自定义学生对象

public class Student {
    private String name;
    private Integer age;

    public Student() {
    }

    public Student(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

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

public class HashmapQiantao {
    public static void main(String[] args) {

        HashMap<String, Integer> hashMap1 = new HashMap<>(); //基础班
        hashMap1.put("张三",20);
        hashMap1.put("李四",22);

        HashMap<String, Integer> hashMap2 = new HashMap<>(); //就业班
        hashMap2.put("王五",21);
        hashMap2.put("赵六",23);

        HashMap<String, HashMap<String, Integer>> hashMap3 = new HashMap<>();//班级类别
        hashMap3.put("1班",hashMap1);
        hashMap3.put("2班",hashMap2);

        Set<Map.Entry<String, HashMap<String, Integer>>> entries = hashMap3.entrySet();
        for (Map.Entry<String, HashMap<String, Integer>> mapEntry:entries
             ) {
            String key = mapEntry.getKey();
            System.out.println(key);
            HashMap<String, Integer> value = mapEntry.getValue();
            Set<Map.Entry<String, Integer>> entries1 = value.entrySet();
            for (Map.Entry<String, Integer> entry: entries1) {
                String key1 = entry.getKey();
                Integer value1 = entry.getValue();
                System.out.println("\t"+key1+" "+value1);
            }
            System.out.println();
        }



    }
}