Comparable接口实现自然排序

商品类：

public class Goods implements Comparable{

    private String name;
    private double price;

    public Goods() {
    }

    public Goods(String name, double price) {
        this.name = name;
        this.price = price;
    }

    public String getName() {
        return name;
    }

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

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    @Override
    public String toString() {
        return "Goods{" +
                "name='" + name + ''' +
                ", price=" + price +
                '}';
    }

    //指明商品比较大小的方式:按照价格从低到高排列,再按照产品名称从低到高
    @Override
    public int compareTo(Object o) {

       if(o instanceof Goods){
           Goods goods=(Goods)o;
           if(this.price> goods.price){
               return 1;
           }else if(this.price< goods.price){
               return -1;
           }else{
               return this.name.compareTo(goods.name);//加上一个符号就是从高到低进行排序了
           }


       }
       throw new RuntimeException("传入的数据类型不一致！");
    }
}

比较器：

import org.junit.Test;

import java.util.Arrays;


public class CompareTest {
    
    @Test

    public void test1(){
        String[] arr=new String[]{"AA","CC","MM","GG","DD"};
        Arrays.sort(arr);
        System.out.println(Arrays.toString(arr));
    }
    @Test
    public void test2(){
        Goods[] arr=new Goods[5];
        arr[0]=new Goods("lenovoMouse",34);
        arr[1]=new Goods("dellMouse",43);
        arr[2]=new Goods("xiaomiMouse",12);
        arr[3]=new Goods("huaweiMouse",65);
        arr[4]=new Goods("microsoftMouse",43);

        Arrays.sort(arr);
        System.out.println(Arrays.toString(arr));


    }
}

如果是String或者包装类，其中已经重写了compareTo()方法，直接调用即可。

如果是自定义类，需要进行排序时，实现Comparable接口，将需要排序的方法写在重写的compareTo()方法中。