模仿双色球前6位

package balls;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class balls {
    public static void main(String[] args) {
        List list=new ArrayList();
        for (int i = 1    ; i <= 33; i++) {
            list.add(i);   
            //System.out.println(list);
        }
        List balls=new ArrayList();
        Random random=new Random();
        
        for (int i = 0; i < 6; i++) {
            int r=random.nextInt(list.size());
            balls.add(list.get(r));
            for(int j=0;j<6;j++){
                if(list.get(r)==balls.get(j)){//现在得到的球和原来的数字对比不重复，此行代码报错
                    balls.remove(i);i--;
                }
            }
            System.out.println(balls);
        }
   
   
    }

}

好的谢谢～