Method 1) Slower Method
 
public void circleSimple(int xCenter, int yCenter, int radius, Color c)
{
         int pix = c.getRGB();
         int x, y, r2;
        
         r2 = radius * radius;
         for (x = -radius; x <= radius; x++) 
         {
           y = (int) (Math.sqrt(r2 – x*x) +  0.5);
           raster.setPixel(pix, xCenter + x,  yCenter + y);
           raster.setPixel(pix, xCenter + x,  yCenter – y);
         }
}
 
 

Method 2) Fastest Method
 
public void circleSym4(int xCenter, int yCenter, int radius, Color c)
{
         int pix = c.getRGB();
         int x, y, r2;
        
         r2 = radius * radius;
         raster.setPixel(pix, xCenter, yCenter +  radius);
         raster.setPixel(pix, xCenter, yCenter -  radius);
         for (x = 1; x <= radius; x++)
         {
           y = (int) (Math.sqrt(r2 – x*x) +  0.5);
           raster.setPixel(pix, xCenter + x,  yCenter + y);
           raster.setPixel(pix, xCenter + x,  yCenter – y);
           raster.setPixel(pix, xCenter – x, yCenter  + y);
           raster.setPixel(pix, xCenter – x,  yCenter – y);
         }
}