创建一个HashMap集合，用于存储学生对象，其中键是学生对象，值是学生所属专业(存入元素后使用键值对遍历)Java代码实现

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

public class Student {
    private String name;
    private String major;

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

    public String getName() {
        return name;
    }

    public String getMajor() {
        return major;
    }

    public static void main(String[] args) {
        Map<Student, String> studentMap = new HashMap<>();
        Student student1 = new Student("Alice", "Computer Science");
        Student student2 = new Student("Bob", "Mathematics");
        Student student3 = new Student("Charlie", "Biology");
        studentMap.put(student1, student1.getMajor());
        studentMap.put(student2, student2.getMajor());
        studentMap.put(student3, student3.getMajor());

        for (Map.Entry<Student, String> entry : studentMap.entrySet()) {
            System.out.println(entry.getKey().getName() + " belongs to " + entry.getValue());
        }
    }
}

输出结果为：

Alice belongs to Computer Science
Charlie belongs to Biology
Bob belongs to Mathematics