【Java】对象排序问题

应用场景：ArrayList里存储一坨对象，按照其中的某个属性，对整个ArrayList进行排序

class someDto{
    private String id;
    private double score;

    someDto(String id, double score) {
        this.id = id;
        this.score = score;
    }

    public String getId() {
        return id;
    }

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

    public double getScore() {
        return score;
    }

    public void setScore(double score) {
        this.score = score;
    }
}

对包含一列someDto的ArrayList，进行排序：

1. 按照id大小进行排序：

Comparator<someDto> cp = Comparator.comparing(someDto::getId);
dtos.sort(cp);   // 顺序
dtos.sort(cp.reversed());  // 逆序

2. 按照score大小进行排序：
   (都能work，但最后一个似乎最好)

//        Comparator<someDto> cp = (a, b) ->  Double.compare(a.getScore(), b.getScore());
//        Comparator<someDto> cp = Comparator.comparing(someDto::getScore);
        Comparator<someDto> cp = Comparator.comparingDouble(someDto::getScore);

---

完整代码：

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

class someDto{
    private String id;
    private double score;

    someDto(String id, double score) {
        this.id = id;
        this.score = score;
    }

    public String getId() {
        return id;
    }

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

    public double getScore() {
        return score;
    }

    public void setScore(double score) {
        this.score = score;
    }
}

public class simpleCompare {
    public static void main(String[] args) {
        List<someDto> dtos = new ArrayList<>();
        dtos.add(new someDto("a", 5));
        dtos.add(new someDto("b", 3));
        dtos.add(new someDto("c", 5));
        dtos.add(new someDto("d", 8));

//        Comparator<someDto> cp = (a, b) -> a.getScore() < b.getScore() ? -1 : 1;
//        Comparator<someDto> cp = (a, b) ->  Double.compare(a.getScore(), b.getScore());
//        Comparator<someDto> cp = Comparator.comparing(someDto::getScore);
        Comparator<someDto> cp = Comparator.comparingDouble(someDto::getScore);
//        Comparator<someDto> cp = Comparator.comparing(someDto::getId);

        dtos.sort(cp.reversed());
        for(someDto dto : dtos) {
            System.out.println("====");
            System.out.println(dto.getId());
            System.out.println(dto.getScore());
        }
    }
}