怎样基于Java实现对象List排序

时间:2021-04-02 人气:0

这篇文章主要介绍了如何基于Java实现对象List排序,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

按照对象中的某个属性，对对象List进行排序。

以初唐四杰的成绩排名为例，对诗人进行排序。

Java实现如下：

1、诗人（Poet）类结构，定义如下：

/**
 * Created by Miracle Luna on 2020/1/11
 */
public class Poet {
  private String name;
  private Double score;

  public Poet(String name, Double score) {
    this.name = name;
    this.score = score;
  }

  public String getName() {
    return name;
  }

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

  public Double getScore() {
    return score;
  }

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

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

2、诗人按照成绩排名，代码如下：

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

/**
 * Created by Miracle Luna on 2020/1/11
 */
public class PoetSort {

  public static void main(String[] args) {
    List<Poet> poetList = new ArrayList<Poet>();
    Poet poet1 = new Poet("杨炯", 94.0);
    poetList.add(poet1);
    Poet poet2 = new Poet("卢照邻", 92.5);
    poetList.add(poet2);
    Poet poet3 = new Poet("骆宾王", 95.0);
    poetList.add(poet3);
    Poet poet4 = new Poet("王勃", 99.5);
    poetList.add(poet4);


    // 初始顺序
    System.out.println("==> 初始顺序如下：");
    poetList.forEach(poet -> System.out.println(poet.toString()));

    // 按照分数排名(从高到低)
    poetList.sort(new Comparator<Poet>() {
      @Override
      public int compare(Poet poet1, Poet poet2) {
        Double score1 = poet1.getScore();
        Double score2 = poet2.getScore();
        return score2.compareTo(score1);
      }
    });
    System.out.println("\n==> 按照分数排名(从高到低)如下：");
    poetList.forEach(poet -> System.out.println(poet.toString()));

    // 按照分数排名(从低到高)
    poetList.sort(new Comparator<Poet>() {
      @Override
      public int compare(Poet poet1, Poet poet2) {
        Double score1 = poet1.getScore();
        Double score2 = poet2.getScore();
        return score1.compareTo(score2);
      }
    });
    System.out.println("\n==> 按照分数排名(从低到高)如下：");
    poetList.forEach(poet -> System.out.println(poet.toString()));
  }
}

3、运行结果如下：

==> 初始顺序如下：
Poet{name='杨炯', score=94.0}
Poet{name='卢照邻', score=92.5}
Poet{name='骆宾王', score=95.0}
Poet{name='王勃', score=99.5}

==> 按照分数排名(从高到低)如下：
Poet{name='王勃', score=99.5}
Poet{name='骆宾王', score=95.0}
Poet{name='杨炯', score=94.0}
Poet{name='卢照邻', score=92.5}

==> 按照分数排名(从低到高)如下：
Poet{name='卢照邻', score=92.5}
Poet{name='杨炯', score=94.0}
Poet{name='骆宾王', score=95.0}
Poet{name='王勃', score=99.5}

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