Чтение файлов внутри a, Jar

Попробуйте следующее:

public static void drawDiamond(int height) {
    if (height % 2 == 0) throw new AssertionError("Height should be an odd number!");
    height = (height + 1) / 2;
    drawTop(height);
    drawBot(height - 1);
}

public static void drawTop(int height) {
    int rows = height;
    int starCount = 1;
    int spaceCount = rows - 1;
    for (int rowCount = 1; rowCount <= rows; rowCount++) {
        for (int i = 0; i < spaceCount; i++) {
            System.out.print(" ");
        }
        for (int i = 0; i < starCount; i++) {
            System.out.print("*");
        }
        starCount += 2;
        spaceCount--;
        System.out.println();
    }
}

public static void drawBot(int height) {
    int rows = height;
    int starCount = 2 * (rows - 1) + 1;
    int spaceCount = 1;
    for (int rowCount = 1; rowCount <= rows; rowCount++) {
        for (int i = 0; i < spaceCount; i++) {
            System.out.print(" ");
        }
        for (int i = 0; i < starCount; i++) {
            System.out.print("*");
        }
        starCount -= 2;
        spaceCount++;
        System.out.println();
    }
}