Java根据list中对象的某个属性降序排序

可以使用Comparator来实现：

1. 定义一个实现Comparator接口的类，实现compare方法，比较list中对象的某个属性，返回比较结果。

public class MyComparator implements Comparator<MyObject> {
    @Override
    public int compare(MyObject o1, MyObject o2) {
        return o2.getProperty() - o1.getProperty(); //降序排列
    }
}

2. 使用Collections.sort()方法进行排序，传入list和自定义的Comparator对象。

List<MyObject> list = new ArrayList<>();
//添加元素
Collections.sort(list, new MyComparator());

完整示例代码：

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

public class SortListByProperty {
    public static void main(String[] args) {
        List<MyObject> list = new ArrayList<>();
        //添加元素
        list.add(new MyObject("obj1", 5));
        list.add(new MyObject("obj2", 3));
        list.add(new MyObject("obj3", 7));
        list.add(new MyObject("obj4", 2));
        list.add(new MyObject("obj5", 9));

        //使用自定义的Comparator进行降序排序
        Collections.sort(list, new MyComparator());

        //打印排序后的结果
        for(MyObject obj : list) {
            System.out.println(obj.getName() + " " + obj.getProperty());
        }
    }

    //自定义对象
    static class MyObject {
        private String name;
        private int property;

        public MyObject(String name, int property) {
            this.name = name;
            this.property = property;
        }

        public String getName() {
            return name;
        }

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

        public int getProperty() {
            return property;
        }

        public void setProperty(int property) {
            this.property = property;
        }
    }

    //自定义Comparator
    static class MyComparator implements Comparator<MyObject> {
        @Override
        public int compare(MyObject o1, MyObject o2) {
            return o2.getProperty() - o1.getProperty(); //降序排列
        }
    }
}

输出结果：

obj5 9
obj3 7
obj1 5
obj2 3
obj4 2