java while循环没有爆发

Question

所以我正在写一个程序,有人从牌组中取出牌.所以我写了一个while循环,循环并检查是否有超过4个随机创建的卡,如果有,更改卡.

这是我的代码:

String card = (int)Math.ceil(Math.random() * 13) + " ";
String[] used2 = used.split(" ");
//used is a String like "12 3 7 8 4 ... # etc" such that it is all the previously drawn cards.
boolean checking = true;
boolean isIn = false;
int in = 0;
int check = 0;
while(checking){
    for(int q = 0; q < used2.length; q++){
        check += 1;
        if(card.equals(used2[q] + " ")){
            in += 1;
            if(in == 4){
                System.out.println(check); //debugging line
                check += 1;
                card = (int)Math.ceil(Math.random() * 13) + " ";
                card_val = (int)Math.ceil(Math.random() * 13);
                isIn = true;
                in = 0;
                break;
            }
        }
    }
    if(isIn){
        //will execute if there is 4 of the cards already drawn so the while loop continues with a different card
        checking = true;
    }
    else{
        //breaks out of while loop because the card can be drawn
        checking = false;
    }
}
used += card;

现在这个运行,但是当我把它放在for循环中并将其设置为运行40次时,大约2/3次它会创建一个无限循环.

我发现只有在if(in == 4)语句出现时才会创建无限循环.

为什么是这样？自昨晚以来我一直在调试,我无法弄清楚这一点.

Answer 1

一旦您设置isIn到true,你从来没有回false.因此,if在底部声明将保持设置checking到true,导致一个无限循环.

设置isIn为循环false的开头while.

while(checking){
    isIn = false;  // Add this line.
    for(int q = 0; q < used2.length; q++){