How to remove “stretch marks” on custom button border?

Question

When performing some custom painting on a button\'s Graphics2D object, I get the following results:

Answer 1

it's because you draw if by drawing several 1px thick borders which misses some pixels in the arcs (draw it again with different colors and zoom in on the image to see it)

use the fill to set the color of the border and then draw the contrasting borders

Color fillcolor = Color.WHITE;
Color bordercolor = Color.BLACK;

if(getModel().isSelected())
{
    fillcolor = Color.BLACK;
}
//fill the full rectangle
g2.setColor(fillcolor);
g2.fillRoundRect(0, 0, getWidth() - 1, getHeight() - 1, ARC_WIDTH, ARC_HEIGHT);

//draw contrasted borders
g2.setColor(bordercolor);
g2.drawRoundRect(0, 0, getWidth() - 1, getHeight() - 1, ARC_WIDTH, ARC_HEIGHT);
g2.setColor(bordercolor);
g2.drawRoundRect(3, 3, getWidth() - 7, getHeight() - 7, ARC_WIDTH, ARC_HEIGHT);