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