Java8 中 Comparator 介面提供了一些靜態方法，可以方便於我們進行排序操作，下面通過例子講解下如何使用

• 對整數列表排序（升序）

  List<Integer> list = Arrays.asList(1, 4, 2, 6, 2, 8);
  list.sort(Comparator.naturalOrder());
  System.out.println(list);

• 對整數列表排序（降序）

  List<Integer> list = Arrays.asList(1, 4, 2, 6, 2, 8);
  list.sort(Comparator.reverseOrder());
  System.out.println(list);
   
  

• 根據物件屬性（年齡）進行排序

  public class Test {
      public static void main(String[] args) {
          List<Person> personList = new ArrayList<>();
          personList.add(new Person("a", 2));
          personList.add(new Person("b", 4));
          personList.add(new Person("c", 7));
          
   
  // 升序
          personList.sort(Comparator.comparingInt(Person::getAge));
          // 降序
          personList.sort(Comparator.comparingInt(Person::getAge).reversed());
          System.out.println(personList);
      }
  
      public static class Person {
          private String name;
          private Integer age;
  
          
   
  public Person(String name, Integer age) {
              this.name = name;
              this.age = age;
          }
  
          public Integer getAge() {
              return age;
          }
          
          // ... toString 方法
      }
  }

• 根據物件屬性（價格、速度）進行排序，需要注意的是，排序有先後之分，不同的順序會導致不同的結果

  public class Test {
      public static void main(String[] args) {
          List<Computer> list = new ArrayList<>();
          list.add(new Computer("xiaomi",4000,6));
          list.add(new Computer("sony",5000,4));
          list.add(new Computer("dell",4000,5));
          list.add(new Computer("mac",6000,8));
          list.add(new Computer("micro",5000,6));
          // 先以價格（升序）、後再速度（升序）
     list.sort(Comparator.comparingInt(Computer::getPrice).thenComparingInt(Computer::getSpeed));
          // 先以速度（降序）、後再價格（升序）
       list.sort(Comparator.comparingInt(Computer::getSpeed).reversed().thenComparingInt(Computer::getPrice));
          // 先以價格（降序）、後再速度（降序）
          list.sort(Comparator.comparingInt(Computer::getPrice).thenComparingInt(Computer::getSpeed).reversed());
          System.out.println(list);
      }
  
      public static class Computer {
          private String name;
          private Integer price;
          private Integer speed;
  
          public Computer(String name, Integer price, Integer speed) {
              this.name = name;
              this.price = price;
              this.speed = speed;
          }
  
          public Integer getPrice() {
  
              return price;
          }
  
          public void setPrice(Integer price) {
              this.price = price;
          }
  
          public Integer getSpeed() {
              return speed;
          }
  
          public void setSpeed(Integer speed) {
              this.speed = speed;
          }
  
          // ... toString 方法
      }
  }