Java HashSet 去重：使用 Student 类存储学生信息

学生类 Student 的定义：

public class Student {
    private String name;
    private String gender;
    private int age;

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

    public String getName() {
        return name;
    }

    public String getGender() {
        return gender;
    }

    public int getAge() {
        return age;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Student other = (Student) obj;
        if (age != other.age)
            return false;
        if (gender == null) {
            if (other.gender != null)
                return false;
        } else if (!gender.equals(other.gender))
            return false;
        if (name == null) {
            if (other.name != null)
                return false;
        } else if (!name.equals(other.name))
            return false;
        return true;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + age;
        result = prime * result + ((gender == null) ? 0 : gender.hashCode());
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        return result;
    }

    @Override
    public String toString() {
        return 'Student [name=' + name + ', gender=' + gender + ', age=' + age + ']';
    }
}

测试类及 main() 方法的定义：

import java.util.HashSet;
import java.util.Set;

public class Test {
    public static void main(String[] args) {
        Student s1 = new Student('张三', '男', 20);
        Student s2 = new Student('李四', '女', 21);
        Student s3 = new Student('张三', '男', 20);

        Set<Student> set = new HashSet<Student>();
        set.add(s1);
        set.add(s2);
        set.add(s3);

        for (Student s : set) {
            System.out.println(s.toString());
        }
    }
}