JAVA8 自定义实现Comparable接口类、Comparator接口

开发过程中如果我们想让某个对象是可比较大小的，那么需要实现Comparable这个接口的方法来满足自然排序。

举例：我们根据鼠标的价格从低到高进行排序，如果价格一样再根据鼠标的名称来进行从低到高排序。

 

class Mouse implements Comparable{
   

    String goodsName;
    int price;

    public Mouse(String name,int price){
        this.goodsName = name;
        this.price = price;
    }

    @Override
    public int compareTo(Object o) {
        if (o instanceof Mouse){
            Mouse mouse = (Mouse) o;
            if (this.price > mouse.price){
                return 1;
            }else if(this.price < mouse.price){
                return -1;
            }else {
                //价格一样按照货物名称排
                return -this.goodsName.compareTo(mouse.goodsName);
            }

        }else {

            throw new RuntimeException("传入的不是鼠标类型");
        }
    }

    @Override
    public String toString() {
        return "Mouse{" +
                "goodsName='" + goodsName + '\'' +
                ", price=" + price +
                '}';
    }
}

@Test
    public void test1(){
        Mouse[] li = new Mouse[5];
        li[0] = new Mouse("XiaoMi",20);
        li[1] = new Mouse("Logitech",50);
        li[2] = new Mouse("lenove",30);
        li[3] = new Mouse("dell",25);
        li[4] = new Mouse("Huawei",50);
        Arrays.sort(li);
        System.out.println(Arrays.toString(li));
    }

这里如果价格一样按照货物名称从高到底进行排序，输出结果为

[Mouse{goodsName='XiaoMi', price=20}, Mouse{goodsName='dell', price=25}, Mouse{goodsName='lenove', price=30}, Mouse{goodsName='Logitech', price=50}, Mouse{goodsName='Huawei', price=50}]

 

 

现在我的Mouse类已经写好了，但是我在排序的时候想要先按照货物名称从高到低，再根据价格从低到高排序，那我们实现的CompareTo方法就不管用了，这里需要使用实现Cpmparator接口来满足定制排序。

@Test
public void test1(){
    Mouse[] li = new Mouse[6];
    li[0] = new Mouse("XiaoMi",20);
    li[1] = new Mouse("Logitech",50);
    li[2] = new Mouse("Lenove",30);
    li[3] = new Mouse("Dell",25);
    li[4] = new Mouse("Huawei",50);
    li[5] = new Mouse("Huawei",52);
    Arrays.sort(li, new Comparator<Mouse>() {
        @Override
        public int compare(Mouse o1, Mouse o2) {
            int i = -o1.goodsName.compareTo(o2.goodsName);
            if (i !=0){
                return i;
            }else {
                int j = o1.price - o2.price;
                if (j>0){
                    return 1;
                }else {
                    return -1;
                }
            }
        }
    });
    System.out.println(Arrays.toString(li));
}

输出结果为

[Mouse{goodsName='XiaoMi', price=20}, Mouse{goodsName='Logitech', price=50}, Mouse{goodsName='Lenove', price=30}, Mouse{goodsName='Huawei', price=50}, Mouse{goodsName='Huawei', price=52}, Mouse{goodsName='Dell', price=25}]