How do I make a color background in java

Question

I need to make a frame pop up and have a color display on the screen with certain dimensions for the window using Jframe or something like that.

Answer 1

JFrame frame = new JFrame("Example");
frame.setBackground(Color.RED); //for color
frame.setPreferredSize(new Dimension(100, 100)); //for size
//...

OR for JPanel

JPanel panel = new JPanel();
panel.setBackground(Color.RED); //for color
panel.setPreferredSize(new Dimension(100, 100)); //for size
//...

Hope it is what you mean.