Thread: Border question

I am having trouble understanding exactly how borders work within the context of a JPanel, especially in regards to using paintComponent. Say I have a JPanel that needs 100x100 of free space to draw and I want a border 10 pixels long on each side; do I have to account for that in my setSize() call? For example, would i do setSize(100,100) or setSize(120, 120)?

And if I want to use paintComponent to draw a rectangle so that it touches the left side of this border, do I need to set the border width as my x-value? I have tried this but it always ends up a few extra pixels to the left. Can anyone give me a definitive explanation on what effect borders have on the absolute positioning of graphics?

I don't know the answer to this right off hand, but if I needed to know, one possible way to find out is to create a small test program that checks out what happens with different settings of border size and component size. Note that I much prefer working with a component's preferredSize rather than its size, and then let my layout managers set the actual size taking the preferredSize into account.

For example:

      JLabel label = new JLabel("Foo");
      label.setPreferredSize(new Dimension(200, 200));
      label.setBorder(BorderFactory.createLineBorder(Color.black, 85));
      JOptionPane.showMessageDialog(null, label);

And now I see the answer and thus know the answer.