Rounded Border on one side only java

Question

I need to create a rounded border on one side of a component only.

This code creates a rounded border:

  new LineBorder(Color.RED, 3, true)

I have seen this thread which shows you how to create a matte border that can be used on one side of a component only, however a matte border isn't rounded.

Is it possible to have a rounded border on one side only?

Edit:

I have tried using compound border like this:

    cell.setBorder(BorderFactory.createCompoundBorder(
        new LineBorder(borderColor, 3, true),
        BorderFactory.createMatteBorder(0, 3, 0, 0, Color.black)));

But it doesn't work...

Answer 1

You can override the method of LineBorder and draw all you need there From sources of LineBorder

    public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
        Color oldColor = g.getColor();
        int i;

    /// PENDING(klobad) How/should do we support Roundtangles?
        g.setColor(lineColor);
        for(i = 0; i < thickness; i++)  {
        if(!roundedCorners)
                g.drawRect(x+i, y+i, width-i-i-1, height-i-i-1);
        else
SET CLIP HERE TO DRAW ONLY NECESSARY PART
                g.drawRoundRect(x+i, y+i, width-i-i-1, height-i-i-1, thickness, thickness);
        }
        g.setColor(oldColor);
    }

Answer 2

LineBorder only supports all corners rounded or not. A compound border (as the JavaDoc states) uses one border for the outside and one for the inside and thus does not distinguish between left/right or top/bottom.

I'm afraid you'd either have to write your own Border implementation or look for one that's already made by someone else (external library).