Java practice: an exercise with loops — printing shapes with asterisks

Here’s how to print various shapes with asterisks. This is a good way to get familiar with nested loops and conditionals.

Hollow square

/*
    hollowSquare(5);
 *****
 *   *
 *   *
 *   *
 *****
*/
    public static void hollowSquare(int n) {
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                if (i == 0 || j == 0 || i == n - 1 || j == n - 1)
                    System.out.print("*");
                else
                    System.out.print(" ");
            }
            System.out.println();
        }
    }

Left bottom triangle

/*
leftBottomTriangle(5);
 *
 **
 ***
 ****
 *****
*/
public static void leftBottomTriangle(int n) {
  for (int i = 1; i <= n; i++) {
   for (int j = 0; j < i; j++) {
    System.out.print("*");
   }
      System.out.println();
  }
}

Right bottom triangle

/*
rightBottomTriangle(5);
     *
    **
   ***
  ****
 *****
*/
    public static void rightBottomTriangle(int n) {
        for (int i = 1; i <= n; i++) {
            for (int j = n; j > i; j--) {
                System.out.print(" ");
            }
            for (int j = 1; j <= i; j++) {
                System.out.print("*");
            }
            System.out.println();
        }
    }

Right top triangle

/*
    rightTopTriangle(5);
 *****
  ****
   ***
    **
     *
*/
    public static void rightTopTriangle(int n) {
        for (int i = n; i > 0; i--) {
            for (int j = 1; j <= n - i; j++) {
                System.out.print(" ");
            }
            for (int j = i; j > 0; j--) {
                System.out.print("*");
            }
            System.out.println();
        }
    }

Hollow left top triangle

/*
hollowLeftTopTriangle(5);
 *****
 *  *
 * *
 **
 *
*/
     public static void hollowLeftTopTriangle(int n) {
        for (int i = n; i > 0; i--) {
            for (int j = i; j > 0; j--) {
                if (i == 1 || i == n || j == 1 || j == i)
                    System.out.print("*");
                else
                    System.out.print(" ");
            }
            System.out.println();
        }
    }

Hollow right top triangle

/*
hollowRightTopTriangle(5);
 *****
  *  *
   * *
    **
     *
*/
     public static void hollowRightTopTriangle(int n) {
        for (int i = n; i > 0; i--) {
            for (int j = n - i; j > 0; j--) {
                System.out.print(" ");
            }
            for (int j = i; j > 0; j--) {
                if (i == 1 || i == n || j == 1 || j == i)
                    System.out.print("*");
                else
                    System.out.print(" ");
            }
            System.out.println();
        }
    }
/*

Hollow left bottom triangle

/*
hollowLeftBottomTriangle(5);
 *
 **
 * *
 *  *
 *****
*/
     public static void hollowLeftBottomTriangle(int n) {
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= i; j++) {
                if (i == 1 || i == n || j == 1 || j == i)
                    System.out.print("*");
                else
                    System.out.print(" ");
            }
            System.out.println();
        }
    }

Hollow right bottom triangle

/*
hollowRightBottomTriangle(5);
     *
    **
   * *
  *  *
 *****
*/
     public static void hollowRightBottomTriangle(int n) {
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n - i; j++) {
                System.out.print(" ");
            }
            for (int j = 1; j <= i; j++) {
                if (i == 1 || i == n || j == 1 || j == i)
                    System.out.print("*");
                else
                    System.out.print(" ");
            }
            System.out.println();
        }
    }

X

/*
xShape(5);
 *   *
  * *
   *
  * *
 *   *
*/
     public static void xShape(int n) {
        //ternary statement for changing size if even
        n = n % 2 == 0 ? n += 1 : n;
         for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++) {
                if (i == j || j + i == (n + 1)) {
                    System.out.print("*");
                } else {
                    System.out.print(" ");
                }
            }
            System.out.println();
        }
        System.out.println();
    }

Bow tie

/*
bowTie(5);
 *    *
 **  **
 ******
 **  **
 *    *
*/
     public static void bowTie(int n) {
        int x = 1;
        int midPoint = n / 2;
        if ((n % 2) == 0) midPoint--;
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                if (j < x || j >= n − x) System.out.print("*");
                else System.out.print(" ");
            }
            if (i < midPoint) x++;
            if (i >= midPoint) x--;
            System.out.println();
        }
    }

Diamond

/*
diamond(4);
     *
    ***
   *****
  *******
 *********
  *******
   *****
    ***
     *
*/
     public static void diamond(int n) {
         for (int i = 0; i < n; i++) {
            for (int j = n; j > i; j--) {
                System.out.print(" ");
            }
            for (int j = 0; j <= i; j++) {
                System.out.print("*");
            }
            for (int j = 0; j < i; j++) {
                System.out.print("*");
            }
            System.out.println();
        }
        for (int i = 0; i <= n; i++) {
            for (int j = 0; j < i; j++) {
                System.out.print(" ");
            }
            for (int j = n; j > i; j--) {
                System.out.print("*");
            }
            for (int j = n; j >= i; j--) {
                System.out.print("*");
            }
            System.out.println();
        }
    }

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