java - 扫描仪被跳过

Question

我正在尝试从用户那里获取 2 个整数。这是我的代码的相关部分:

 public void play() {

        int row=0,col=0;
        initializeboard();
        printboard();

        do {

            currentPlayer = players.remove();  //Returns currentPlayer
            System.out.println("Ok, "+ currentPlayer.getname() + ", Enter your Move: Row[1-3] & Column[1-3]");
            Scanner choice = new Scanner(System.in);
            if (choice.hasNext()) {

                row = choice.nextInt();
                col = choice.nextInt();
                while (row<1 || row>3 || col<1 || col>3 || board[row-1][col-1] != '-' ) {
                    System.out.println("Well, Move is not Valid or has already Been Selected, Try Again :/");
                    row = choice.nextInt();
                    col = choice.nextInt();
                }
                choice.close();
            }

            board[row][col] = currentPlayer.getsign(); //Places Sign in Game Board
            printboard();
            System.out.println();
            players.append(currentPlayer); //Inserts the Next Player
        } while(!win() && !isFull());
}

首先，它抛出NoSuchElementException，所以我使用了.hasNext()。现在，它只是跳过扫描仪并立即调用 printboard()。

Answer 1

问题在于您正在使用同一流创建然后关闭多个 Scanner 对象。

Peter Lawrey 在 this post 中的回答解释了为什么不应从同一流创建多个 Scanner 对象。以下是答案的引用:

Once you close a stream it closes the underlying stream and you can't use it again. Only close System.in if you want to prevent it being used again.

最好的办法是在程序中创建一个 final Scanner 对象(每个流)，然后在需要使用它时将其传递到方法中:

static final Scanner scan = new Scanner(System.in);