Student实体类实现HashSet集合，唯一性

Love The Way You Lie 2023-10-10 22:39 132阅读 0赞

Student类如下所示：

package com.test.Test07;
    
    import java.util.Objects;
    
    public class Student {
        private int age;
        private String name;
    
        public int getAge() {
            return age;
        }
    
        public void setAge(int age) {
            this.age = age;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        @Override
        public String toString() {
            return "Student{" +
                    "age=" + age +
                    ", name='" + name + '\'' +
                    '}';
        }
    
        public Student(int age, String name) {
            this.age = age;
            this.name = name;
        }
    
        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            Student student = (Student) o;
            return age == student.age &&
                    Objects.equals(name, student.name);
        }
    
        @Override
        public int hashCode() {
            return Objects.hash(age, name);
        }
    }

测试类如下所示：

package com.test.Test07;
    
    
    import java.util.HashSet;
    
    public class TestStudent {
        //这是一个main方法，是程序的入口
        public static void main(String[] args) {
            //创建一个HashSet集合
            HashSet<Student> hs = new HashSet<>();
            hs.add(new Student(19,"lili"));
            hs.add(new Student(20,"lulu"));
            hs.add(new Student(18,"feifei"));
            hs.add(new Student(19,"lili"));
            hs.add(new Student(10,"nana"));
    
    
            System.out.println(hs.size());  // 5
            System.out.println(hs);         //[Student{age=18, name='feifei'}, Student{age=10, name='nana'}, Student{age=20, name='lulu'}, Student{age=19, name='lili'}, Student{age=19, name='lili'}]
    
            /*
            //现在就变成了4条数据，HashSet符合唯一性的特点了。
            4
                    [Student{age=18, name='feifei'}, Student{age=19, name='lili'}, Student{age=20, name='lulu'}, Student{age=10, name='nana'}]*/
    
    
        }
    }