从数组列表中删除元素不起作用，是否发生重复？（基本宾果游戏）

Question

I tired to make a super basic bingo go(no need to over complicate stuff)

package bingo;

 import java.util.*;

public class Bingo {

public static void main(String[] args) {

    Random rn = new Random();
    ArrayList bingo = new ArrayList();
    final int MAX = 50;
    int no  = rn.nextInt(49);
    boolean finished = false;

    for(int i = 0; i < MAX; i++){
        bingo.add(i);
    }


    while(!finished){
       // Keep the number it can generate the same size as the array-list
        no  = rn.nextInt(bingo.size());

is this where it goes wrong? instead of removing the number eg "10", does it remove the element in position 10 in the array?

  if(bingo.contains(no)){
            System.out.println(no);
            bingo.remove(no);
        }

        if(bingo.isEmpty()){
            finished = true;
        }
    }

}

}

Answer 1

bingo.remove(no) calls remove(int index) , which removes the element whose index is no , not the element whose value is no . If you want to remove the element whose value is no, you need to use remove(Object o) , which expects a reference type. For example, bingo.remove(Integer.valueOf(no)); .

Answer 2

There are two overloaded version of remove method in arrayList.

Difference between two overloaded api of remove method is One that accepts Object and other which accepts primitive index parameter. And you are specifying primitive value ie 10.

If you want to remove element with content as 10, you change the following line from:

int no  = ...

To

Integer no  = ...