Java 为什么while循环永远不会结束？

我试图询问扫描仪输入，直到我得到一个有效的答案，但我的while循环并没有结束。首先，我请求用户输入，然后如果输入有效，我将打印出坐标，如果输入无效，我将抛出一个错误并再次请求输入。 这是我的代码：

public static String[] positionQuery(int dim, Scanner test_in) {
        String[] coordinates;
        Scanner stdin = new Scanner(System.in);
        System.out.println("Provide origin and destination coordinates.");
        System.out.println("Enter two positions between A1-H8:");
        String s1 = stdin.nextLine();
        coordinates = s1.split(" ");
        String origin = coordinates[0];
        String dest = coordinates[1];

        while (!validCoordinate(origin,dim) || !validCoordinate(dest,dim) || coordinates.length != 2) {
            System.out.println("ERROR: Please enter valid coordinate pair separated by space.");
            Scanner stdin2 = new Scanner(System.in);
            System.out.println("Provide origin and destination coordinates.");
            System.out.println("Enter two positions between A1-H8:");
            String s2 = stdin.nextLine();
            coordinates = s1.split(" ");
            String origin2 = coordinates[0];
            String dest2 = coordinates[1];
        }
        return coordinates;

    }

我怎样才能修好它？我还尝试了do while循环，但循环仍然没有终止：

public static boolean validCoordinate(String coordinate, int dimension) {
    String [] alphabet = {"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"};
    int [] numbers = new int [dimension];
    int one = 1;
    for(int i = 0; i < dimension; i++){
        numbers[i] = one + i;
    }
    String[] validC = new String [dimension]; //if the first char  is a letter + a number that is determined my the dimension (string concat
    for(int i = 0; i < dimension; i++) {
        for(int j = 0; j < dimension; j++){
            validC [i] = alphabet[j] + Integer.toString(numbers[j]);
        }
    }

    for(int i = 0; i < dimension; i ++) {
        if(validC[i].equals(coordinate)) {
            return true;
        }
        else {
            return false;
        }
    }
        return true;
}

---

在

origin

、

dim

和

dest

的循环中，您从不修改

origin

、

dim

和

dest

<代码>！有效坐标（原点，dim）| |！validCoordinate（dest，dim）使用Scanner作为参数调用方法

positionQuery

，并在方法内部创建更多的Scanner实例。这是错误的，您一次只能有一个扫描仪连接到System.in，因此请使用作为函数参数传递的扫描仪。扫描仪输入应该在循环中，对吗？这是否回答了您的问题？

public static String[] positionQuery(int dim, Scanner test_in) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Provide origin and destination coordinates.");
        System.out.println("Enter two positions between A1-H8:");
        while(true) {
            String line = scanner.nextLine();
            String[] coordinates = line.split(" ");
            if(coordinates.length == 2) {
                String origin = coordinates[0];
                String dest = coordinates[1];
                if(validCoordinate(origin, dim) && validCoordinate(dest,dim)) {
                    return coordinates;
                }
            }
            System.out.println("ERROR: Please enter valid coordinate pair separated by space.");
        }
    }