java1.8特性之多重排序简单示例

Posted 2021-02-06 superdrew

java1.8新特性：多重排序，简化比较器排序代码量。亲测有效！

1. 实体类：Student.java

package java8newfeture;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

import com.google.common.collect.Lists;

/**
 * @author zero 2019/01/26
 */
public class Student {
    private int id;
    private String name;

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Student() {

    }

    /**
     * @param id
     * @param name
     */
    public Student(int id, String name) {
        super();
        this.id = id;
        this.name = name;
    }

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

}

2. 测试类：SortStudent.java

package java8newfeture;

import java.util.ArrayList;
import java.util.Comparator;

import com.google.common.collect.Lists;

/**
 * @author zero 2019/01/26
 */
public class SortStudent {

    public static void main(String[] args) {
        ArrayList<Student> students =
            Lists.newArrayList(new Student(1, "A2"),new Student(1, "A1"), new Student(3, "C3"), new Student(2, "B2"));
        // 默认是升序排序，降序为comparing(Student::getId).reversed().thComparing(Student::getName)
        // 如果是需要按照某个字段降序排序，则在后面调用方法reversed()
        students.sort(Comparator.comparing(Student::getId).thenComparing(Student::getName));
        students.forEach(System.out::println);
    }

}

3. 测试结果：

4. 结论：亲测有效，请自己扩展尝试！