java 排序调用

import java.util.*;

/**
 * @ClassName CollectionTest
 * @Description To
 * @Author BlazeJack
 * @Date 2019/9/10 10:51
 * @Version 1.0
 **/

class MyIntCom implements Comparator{
    public int compare(Object o1, Object o2) {
     Integer a = (Integer) o1;
        Integer b = (Integer) o2;
        //小于返回-1，个人认为是前面减去后面
        if(a<= b){
            return -1;
        }
        return 1;
    }
}
public class CollectionTest {
    public static  String check(List <Integer>list){
        int len = list.size();
        for(int i = 1; i < len; i++){
            Integer a = list.get(i-1);
            Integer b = list.get(i);
            if( a> b){
                return "false";
            }
        }
        return "true";
    }
    public static void main(String[] args) {
        {
            List<Integer> num = new ArrayList();
            Random random = new Random();
            int size =10000;
            for(int i = 0; i < size; i++){
                num.add(random.nextInt(size));
            }
            System.out.println(num);
            Collections.sort(num,new MyIntCom());
//            Collections.sort(num );
            System.out.println(num);
            System.out.println(check(num));
        }

    }
}