Print out an ASCII circle of the specified width

Question

I'm trying to change the following code so I get this output for radius 2:

  *****
***   ***
**     **
***   ***
  *****

Any help will be appreciated as I'm about to go crazy!

public class Main {
    public static void main(String[] args) {
        // dist represents distance to the center
        double dist;
        double radius = 2;

        // for horizontal movement
        for (int i = 0; i <= 2 * radius; i++) {
            // for vertical movement
            for (int j = 0; j <= 2 * radius; j++) {
                dist = Math.sqrt(
                        (i - radius) * (i - radius) +
                        (j - radius) * (j - radius));

                // dist should be in the range (radius - 0.5)
                // and (radius + 0.5) to print stars(*)
                if (dist > radius - 0.5 && dist < radius + 0.5)
                    System.out.print("*");
                else
                    System.out.print(" ");
            }
            System.out.println("");
        }
    }
}

Answer 1

The output looks oval because characters do not have same width and height. Think of an image that its pixels are not square, but vertical rectangles. I borrowed the c# version of the code linked by @Prasanth Rajendran, and made some modifications:

1. added lineWidth argument
2. added xScale argument, now every 1/xScale characters in a row are equivalent to 1 data points
3. moved character position to its center, by adding a [0.5, 0.5] offset

// function to print circle pattern 
static void printPattern(int radius, int lineWidth, double xScale)
{
    double hUnitsPerChar = 1 / xScale;
    double hChars = (2 * radius + lineWidth) / hUnitsPerChar;
    double vChars = 2 * radius + lineWidth;
    // dist represents distance to the center 
    double dist;
    double lineWidth_2 = (double)lineWidth / 2;
    double center = radius + lineWidth_2;
    // for vertical movement 
    for (int j = 0; j <= vChars - 1; j++)
    {
        double y = j + 0.5;
        // for horizontal movement 
        for (int i = 0; i <= hChars - 1; i++)
        {
            double x = (i + 0.5) * hUnitsPerChar;
            dist = Math.Sqrt(
                (x - center) * (x - center) +
                (y - center) * (y - center));

            // dist should be in the range  
            // (radius - lineWidth/2) and (radius + lineWidth/2)  
            // to print stars(*) 
            if (dist > radius - lineWidth_2 &&
                            dist < radius + lineWidth_2)
                Console.Write("*");
            else
                Console.Write(" ");
        }

        Console.WriteLine("");
    }
}
static void Main(string[] args)
{
    printPattern(2, 1, 2);
    printPattern(10, 3, 2);
}

Now the results are like this:

printPattern(2, 1, 2):

  ******
***    ***
**      **
***    ***
  ******

printPattern(10, 3, 2):

                **************
            **********************
         ****************************
      ***********            ***********
     ********                    ********
   ********                        ********
  *******                            *******
 *******                              *******
 ******                                ******
******                                  ******
******                                  ******
******                                  ******
******                                  ******
******                                  ******
 ******                                ******
 *******                              *******
  *******                            *******
   ********                        ********
     ********                    ********
      ***********            ***********
         ****************************
            **********************
                **************

They look better in CMD:

Hope you can translate it to java.

Answer 2

You can draw the edge of a circle inside of itself and represent the Equation of a circle as:

double edge = (x*x + y*y) / (double) r - r;

If the radius r=2 and the line width w=1, then the circle looks like this:

  ******  
****  ****
**      **
****  ****
  ******  
r=2,w=1.0

Assume that the width of two characters is equal to the height of one character.

Try it online!

// radius
int r = 12;
// line width
double w = 3;
// assume that the width of two characters
// is equal to the height of one character
for (int y = -r; y <= r; y++) {
    for (int x = -r; x <= r; x++) {
        double edge = (x*x + y*y) / (double) r - r;
        // edge is inside the circle
        if (edge > - w*4/3 && edge < 1) {
            System.out.print("**");
        } else {
            System.out.print("  ");
        }
    }
    System.out.println();
}
System.out.println("r="+r+",w="+w);

Output:

                  **************                  
              **********************              
          ******************************          
        **********              **********        
      ********                      ********      
    ********                          ********    
    ******                              ******    
  ******                                  ******  
  ******                                  ******  
******                                      ******
******                                      ******
******                                      ******
******                                      ******
******                                      ******
******                                      ******
******                                      ******
  ******                                  ******  
  ******                                  ******  
    ******                              ******    
    ********                          ********    
      ********                      ********      
        **********              **********        
          ******************************          
              **********************              
                  **************                  
r=12,w=3.0

---

^{See also:
• Print out an ASCII circle and axes with characters
• Printing multiline ASCII animation in the console}