How to get the inner frame in java swing?

Question

I was building a simplistic "game" as sort of tutorial into developing apps or such in java. My Main class extends JFrame . It was just moving a ball around the screen. After getting to the point where I can move the ball can move I started implementing collision with the boundaries of the window and spent several minutes trying to figure out why the only went some beyond the border on 3 sides and then far beyond the top before I realized that the boundaries were being obeyed but that they were the edges of the actual window, beyond the display area.

How would I set up the Main class so that the boundaries are the visible area? Would it extend a different class? And then what it be inside of something else?

Answer 1

• It's hard to say what you may be doing wrong without code,
• but for one thing, you should never be drawing directly in the JFrame and should avoid extending JFrame.
• Instead extend JPanel, get it's boundaries, and draw in this JPanel.
• Also, make sure to override the JPanel's paintComponent(...) method,
• to also call the super.paintComponent(g) inside the override.
• Put the JPanel into a JFrame for display.
• Make sure to check out the Swing drawing tutorials before doing this coding because often you have to change basic assumptions when doing graphics program and especially animation programs.