嵌套while循环在嵌套循环完成之前执行顶部循环- Java

Question

我正在做《Connect Four》游戏练习。除错误检查外，一切正常。用户输入一个字符串，我需要首先检查它的长度和格式是否正确(嵌套while-loop)，然后检查条目是否创建了一个赢家来结束游戏(顶部while-loop)。

但是，即使条目无效，嵌套while-loop应该仍在循环，Java也会在外部while-loop中执行其余代码。我哪里做错了?

while (true) {
    // get row and column from user
    int row=1, column=1;
    boolean validr = false, validc = false;
    do {
        System.out.print("Type the row and column you would like to drop your chip, separated by a space: ");
        String drop = keyboard.nextLine();
        // check that input is proper length
        if(drop.length() == 3 && drop.contains(" ")) {
            int space = drop.indexOf(" ");
            // check if row is integer
            try { 
                int testrow = Integer.parseInt(drop.substring(0, space));
                //check if between 1 and 6
                if (testrow > 0 && testrow < 7) {
                    row = Integer.parseInt(drop.substring(0, space));
                    validr = true;
                } else {
                    System.out.println("Whoops, that row isn't valid!");
                }
            } catch (NumberFormatException ex) {
                System.out.println("Make sure you're typing valid row and column numbers!");
            }
            // check if column is valid
            try {
                int testcolumn = Integer.parseInt(drop.substring(space+1));
                //check if between 1 and 7
                if (testcolumn > 0 && testcolumn < 8) {
                    column = Integer.parseInt(drop.substring(space+1));
                    validc = true;
                } else {
                    System.out.println("Whoops, that column isn't valid!");
                }
            } catch (NumberFormatException ex) {
                System.out.println("Make sure you're typing valid row and column numbers!");
            }
        } else {
            System.out.println("Remember, type the row number, followed by a space, and then the column number.");
        }
    } while (!validr && !validc);
    // change selected array value to 'x'
    board[row-1][column-1] = "x";
    // check if there is now a winner
    if (checkBoard(board) == true) {
        printBoard(board);
        System.out.println("Congratulations!  You got four in a row!");
        break;
    }
    else {
        printBoard(board);
    }
}

它将显示抛出的任何异常的错误消息，但它也会将board[1][1]更改为"x"，并从粘贴在这里的整个代码的顶部开始，而不仅仅是嵌套while-loop的顶部。

Answer 1

您的

 while (!validr && !validc);

条件表示只要validr和validc都为假(即行号和列号都无效)，内循环将继续进行。

您需要validr和validc都为真才能退出内循环，因此您的条件应该是:

while (!validr || !validc);

。只要validr或validc为假，循环就会继续。

Answer 2

!(a&b)= !a ||"非(A和B)"等同于"(非A)或(非B)"

dm定律里。在你的程序中应用它你的while循环应该是

while (!validr || !validc);