更改 JFrame 的背景颜色

Question

I am trying to change the color of a JFrame with no components inside it, but I can't seem to figure it out...

JFrame frame = new JFrame();
frame.setTitle("");
// Attempts to change the color
frame.setBackground(Color.BLACK);
frame.setForeground(Color.BLACK);
// Attempts to change the color
frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
frame.setResizable(false);  
frame.setVisible(true);

Answer 1

Use frame.getContentPane().setBackground(Color.BLACK); to set the color.

Answer 2

JFrame frame = new JFrame();
frame.setTitle("");
// Attempts to change the color
frame.setBackground(Color.BLACK);
frame.setForeground(Color.BLACK);
// Attempts to change the color
frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
frame.setResizable(false);  
frame.setVisible(true);

You must use the frame as a undecorated jframe The New Code Here

JFrame frame = new JFrame();
setUndecorated(true);
frame.setTitle("");
// Attempts to change the color
frame.setBackground(Color.BLACK);
frame.setForeground(Color.BLACK); // by this code you haven't give a black foreground so remove this line 
// Attempts to change the color
frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
frame.setResizable(false);  
frame.setVisible(true);

If you not want to undecorate JFrame

You can use a JPanel instead it.

Or use Answer No 1

But you can only use this fr.getContentPane().setBackground(Color.BLACK); code in main method.

So Use this this answer's code.