List接口-sort 比较器

import java.util.ArrayList;
import java.util.Comparator;

public class DemoClass4Comparator {
   public static void main(String[] args) {
      //TODO 比较器的使用
      ArrayList arrayList = new ArrayList();
      arrayList.add(1);
      arrayList.add(3);
      arrayList.add(2);

      arrayList.sort(new intComparator());
      System.out.println(arrayList);

   }
}

class intComparator implements Comparator<Integer> {
   public int compare(Integer o1, Integer o2) {
      return o1 - o2;  //[1, 2, 3]  顺序排列
      //return o2 - o1; //[3, 2, 1] 倒序排列
      //return 0; //[1, 3, 2]
   }
}