使用JavaCollections类的sort对List集合排序的两种方法

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1.实现Comparable接口

//实体类
public class Car implements Comparable<Car> {
private Integer price;

   public Integer getPrice() {
       return price;
   }
   public void setPrice(Integer price) {
       this.price = price;
   }

   @Override
   public int compareTo(Car c) {
       if(this.price>c.getPrice()){
           return -1;
       }else if(this.price<c.getPrice()){
           return 1;
       }else{
           return 0;
       }
}

//main

        List<Car> listCar = new ArrayList<Car>();
       Car c1 = new Car();
       Car c2 = new Car();
       Car c3 = new Car();
       c1.setPrice(2000);
       c2.setPrice(1000);
       c3.setPrice(3000);
       listCar.add(c1);
       listCar.add(c2);
       listCar.add(c3);

       for (Car car : listCar) {
           System.out.println(car.getPrice());
       }
       System.out.println("================");
       //进行排序
       Collections.sort(listCar);
       for (Car car : listCar) {
           System.out.println(car.getPrice());
       }

2.使用匿名内部类

实体类不要实现任何借口

       // 降序排序    升序 -1 和 1 调换下
       Collections.sort(carList,new Comparator<Car2>() {
           @Override
           public int compare(Car2 o1, Car2 o2) {
               if(o1.getPrice()>o2.getPrice()){
                   return 1;
               }else if(o1.getPrice()<o2.getPrice()){
                   return -1;
               }else{
                   return 0;
               }
           }
       });

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