java - 程序期间重置全局字符数组的值

Question

对于一个学校项目，我已经开始制作一个数独解算器程序，这就是我迄今为止为入门系统提出的方案。唯一的问题是，每当我在输入问题后使用 displayProblem 方法时，它都会显示完全空白(即所有字符都设置为“0”)。有人能帮我解决这个问题吗？

public class Main {
AQAConsole2013 c = new AQAConsole2013();
char[] prob = new char[81];

Main() {
    initProblem();
    int choice = useMenu();
    if (choice == 0) {
        closeProgram();
    } else {
        redirectChoice(choice);
        new Main();
    }
}

public void initProblem() {
    for (int i = 0; i != 81; i++) {
        prob[i] = '0';
    }
}

public int useMenu() {
    displayMenu();
    return getChoice();
}

public void displayMenu() {
    c.println("Sudoku Solver:");
    c.println("---------------------------");
    c.println("1. Load Problem");
    c.println("2. Display Current Problem");
    c.println("3. Solve by Brute Force");
    c.println("4. Help");
    c.println("0. Exit Program");
}

public int getChoice() {
    int x = -1;
    while (x > 4 || x < 0) {
        x = c.readInteger("\nChoose an option: ");
        if (x > 4 || x < 0) {
            c.println("That is not a valid choice.");
        }
    }
    return x;
}

public void redirectChoice(int x) {
    switch (x) {
    case 1:
        loadProblem();
        break;
    case 2:
        displayProblem();
        break;
    case 3:
        break;
    case 4:
        break;
    }
}

public void loadProblem() {
    c.println("\nTo enter a problem into the application, label each column A-I from left to right, and label each row 1-9 from top to bottom.\nLabel unknowns with a hyphen (-)\nAny multiple digit number entered will be saved as just the first digit (23 would be saved as just 2)\nIf you make a mistake, you can type \'r\' to start again.\n");
    populateProblem();
}

public void populateProblem() {
    char[] x = new char[81];
    char[] iChar = new char[10];
    for (int i = 0; i != 9; i++) {
        iChar = numToChar(i);
        for (int j = 1; j != 10; j++) {
            while (x[(i * 9 + j) - 1] != '1' && x[(i * 9 + j) - 1] != '2'
                    && x[(i * 9 + j) - 1] != '3'
                    && x[(i * 9 + j) - 1] != '4'
                    && x[(i * 9 + j) - 1] != '5'
                    && x[(i * 9 + j) - 1] != '6'
                    && x[(i * 9 + j) - 1] != '7'
                    && x[(i * 9 + j) - 1] != '8'
                    && x[(i * 9 + j) - 1] != '9'
                    && x[(i * 9 + j) - 1] != '-'
                    && x[(i * 9 + j) - 1] != 'r') {
                try {
                    x[(i * 9 + j) - 1] = c
                            .readChar("Enter the value for square "
                                    + iChar[i] + j + ": ");
                } catch (StringIndexOutOfBoundsException e) {
                    c.println("That is not a valid value.");
                }
            }
            if (x[(i * 9 + j) - 1] != '1' && x[(i * 9 + j) - 1] != '2'
                    && x[(i * 9 + j) - 1] != '3'
                    && x[(i * 9 + j) - 1] != '4'
                    && x[(i * 9 + j) - 1] != '5'
                    && x[(i * 9 + j) - 1] != '6'
                    && x[(i * 9 + j) - 1] != '7'
                    && x[(i * 9 + j) - 1] != '8'
                    && x[(i * 9 + j) - 1] != '9'
                    && x[(i * 9 + j) - 1] != '-'
                    && x[(i * 9 + j) - 1] != 'r') {
                c.println("That is not a valid value.");
            } else if (x[(i * 9 + j) - 1] == 'r') {
                c.println("------------------------------");
                populateProblem();
            }
        }
    }
    for (int k = 0; k != 81; k++) {
        prob[k] = x[k];
    }
    c.println("");
}

public char[] numToChar(int x) {
    char[] a = new char[10];
    for (int i = 0; i != 10; i++) {
        a[i] = (char) (i + 65);
    }
    return a;
}

public void displayProblem() {
    c.print("");
    for (int i = 0; i != 9; i++) {
        c.println("\t");
        if (i == 0 || i == 3 || i == 6) {
            c.println("------------------");
        }
        for (int j = 1; j != 10; j++) {
            char y = ' ';
            if (j == 0 || j == 3 || j == 6 || j == 9) {
                y = '|';
            }
            c.print(prob[(i * 9 + j) - 1]);
            c.print(y);
        }
    }
    c.println("\n------------------\n");
}

public void closeProgram() {
    c.println("\nGoodbye.");
    System.exit(0);
}

public static void main(String[] args) {
    new Main();
}

}

Answer 1

问题出在这里:

} else {
    redirectChoice(choice);
    new Main();
}

在用户选择加载板并且它被加载之后您正在创建一个新的 Main 对象以再次显示菜单。事情是这样的板已加载到“旧”Main 对象，因此当用户想要显示时板，它是空的 - 因为它是来自新创建的 Main 对象的板。