java 比较器的使用

创建bean

public class Student {

    private Integer id;
    private String name;

    public Student() {
    }

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


    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        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 Objects.equals(id, student.id) &&
                Objects.equals(name, student.name);
    }

    @Override
    public int hashCode() {
        return Objects.hash(id, name);
    }

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

自定义比较器

public class IdComparator implements Comparator<Student> {

    @Override
    public int compare(Student o1, Student o2) {
        //返回负数，第一个参数排在前面
        //返回正数，第二个参数排在前面
        return o1.getId()-o2.getId();
    }
}

使用

public static void main(String[] args) {
    Student student1 = new Student(1, "ddd");
    Student student2 = new Student(2, "ccc");
    Student student3 = new Student(3, "bbb");
    Student student4 = new Student(4, "aaa");
    Student[] arrStudents = {student3, student2, student1, student4};
    Arrays.sort(arrStudents,new IdComparator());
    for (Student arrStudent : arrStudents) {
        System.out.println(arrStudent);
    }
}

结果：

Student{id=1, name='ddd'}
Student{id=2, name='ccc'}
Student{id=3, name='bbb'}
Student{id=4, name='aaa'}

Process finished with exit code 0