Diamond outline pattern java using loops

Question

I\'m a novice in java and I\'m a little bit of trouble trying to get the output I need. I\'m trying to make a Diamond outline pattern using nested loops in java. The output I ne

Answer 1

You were close enough, just some small changes

public static void drawDiamond(int n) {
    int spaces = n - 1;
    for (int i = 0; i < 2 * n - 1; i++) {
        for (int j = 0; j < spaces; j++)
            System.out.print(" ");
        System.out.print(n - spaces);
        for (int j = 0; j < (2 * n - 2 * spaces - 3); j++)
            System.out.print(" ");
        if (i != 0 && i != 2 * n - 2)
            System.out.print(n - spaces);
        if (i < ((2 * n) - 1) / 2)
            spaces--;
        else
            spaces++;
        System.out.println();
    }
}

Answer 2

Alright, this is how you have to look at it.

1. Ignore the top and bottom points. Those are easy to draw. We will make a for loop that will print the middle section that contains 2 chars per line.
2. make a method that will take in an integer n and print n spaces.
3. Figure out how many spaces you need for each line on the left and right sides of the diamond. This is how:

LEFT SIDE:
Example n=4 (same as above). We need to print 5 lines that contain 2 chars if n=4. We need to figure out how many spaces each line needs for this left side. x is line # and y is # of spaces.

x y
1 3
2 2
3 1
4 2
5 3

Now we need a linear function, y=mx+b, that will create the above table.
The answer is y=|x-3|+1.

Now, rather than the example of n=4, what will this linear function be for any n?
y=|x-(n-1)|+1.
or, in java,
int y = Math.abs(x - (n-1)) + 1;

RIGHT SIDE
Now, repeat with right side of the diamond. X is line # and y is # of spaces required.

x y
1 2
2 4
3 6
4 4
5 2

Again, we need a linear function that creates this table.
The answer is y=6-|3-x|*2.

Again, for any n, you will get
int y= (2*(n-1)) - Math.abs((n-1) - x)*2;

Filling in #s rather than x's and printing the top and bottom points should be easy, didn't include it below.
After doing all this, I realized the top and bottom points cannot be a perfect point (can't do half spaces), so the functions will need modification to the following...
int secondSpace = (2*(n-1)) - Math.abs((n-1) - i)*2;
will become
int secondSpace = (2*(n-1)) - Math.abs((n-1) - i)*2-1;

    public static void drawDiamond(int n) {
        int numbLinesWith2xs = 2*n - 3;
        for (int i = 1; i <= numbLinesWith2xs; i++) {
            int firstSpace = Math.abs(i - (n-1)) + 1;
            int secondSpace = (2*(n-1)) - Math.abs((n-1) - i)*2;

            printSpaces(firstSpace);
            System.out.print("x");
            printSpaces(secondSpace);
            System.out.println("x");
        }
    }

    public static void printSpaces(int n) {
        for (int i=1; i<=n; i++) {
            System.out.print(" ");
        }
    }

 //RESULT for drawDiamond(8):

       x  x
      x    x
     x      x
    x        x
   x          x
  x            x
 x              x
  x            x
   x          x
    x        x
     x      x
      x    x
       x  x

final solution with everything included:

public static void drawDiamond(int n) {
        int numbLinesWith2xs = 2*n - 3;
        printSpaces(n);
        System.out.println("1");
        for (int i = 1; i <= numbLinesWith2xs; i++) {
            int firstSpace = Math.abs(i - (n-1)) + 1;
            int secondSpace = (2*(n-1)) - Math.abs((n-1) - i)*2-1;
            printSpaces(firstSpace);
            System.out.print(secondSpace/2+2);
            printSpaces(secondSpace);
            System.out.println(secondSpace/2+2);
        }
        printSpaces(n);
        System.out.println("1");
    }


    1
   2 2
  3   3
 4     4
  3   3
   2 2
    1