我正在嘗試將char的2d數組初始化為空格，但是控制台中的輸出很奇怪

Question

以下是我的構造函數，我嘗試使用spaces初始化數組，但是當我打印出*作為邊框（在我的toString中）時，奇怪的是控制台中的輸出

// constructs a screen based on the dimensions
public Screen(int height, int width) {
    screen = new char[height+2][width+2];
    for (int i = 0; i < screen.length; i++) {
        for (int j = 0; j < screen[i].length; j++) {
            screen[i][j] = ' ';
        }
    }
}

輸出低於

---

*
Ū
ʪ
Ϫ
Ԫ
％
ު
࣪
ਪ
୪୪୪୪୪୪୪୪୪୪୪

我構造了一個9 x 9屏幕，我不知道哪里出了問題。

public String toString() {
    String str = "";
    for (int row = 0; row < screen.length; row++) {
        for (int col = 0; col < screen[row].length; col++) {
            if (row == 0 || col == 0 || row == screen.length-1) {
                str += border;
            } else {
                border += screen[row][col];
            }
        }
        str += "\n";
    }
    return str;
}

Answer 1

您的toString看起來很奇怪。

你寫了 ：

if (row == 0 || col == 0 || row == screen.length-1) {
    str += border;
} else {
    border += screen[row][col];
}

應該是： str += screen[row][col];

更好的解決方案

盡管如此，以前的解決方案仍然可以使用，我建議您采用這種方式：

public static class Screen {
    private char[][] screen;
    private static final String BORDER = "*";

    public Screen(int height, int width) {
        screen = new char[height][width];
        for (int i = 0; i < screen.length; i++) {
            for (int j = 0; j < screen[i].length; j++) {
                screen[i][j] = ' ';
            }
        }
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        // add (screen.length + 2) for the first line.
        for (int i = 0; i < screen.length + 2; i++) {
            sb.append(BORDER);
        }
        sb.append(System.getProperty("line.separator"));

        for (int i = 0; i < screen.length; i++) {
            // star at the begin of each line
            sb.append(BORDER);
            for (int j = 0; j < screen[i].length; j++) {
                sb.append(screen[i][j]);
            }
            // star at the end of each line
            sb.append(BORDER);
            sb.append(System.getProperty("line.separator"));
        }

        // add (screen.length + 2) for the last line.
        for (int i = 0; i < screen.length + 2; i++) {
            sb.append(BORDER);
        }

        return sb.toString();
    }
}

通過這種方式打印牆陣列，您不會覆蓋邊框內容。 （在數組周圍添加星號，而不是邊框 ）