JFrame背景颜色不会改变吗？

Question

So, I'm trying to display a simple JFrame but I'm unable to change the background color? Did a few searches and they all suggest to use useContentPane which I have.

 import java.awt.*;

import javax.swing.*; 


public class Login {

     public static void main(String[] args) {

         createWindow();

         } 

    private static void createWindow() {
        JFrame frame = new JFrame("Login System");
        frame.getContentPane().setBackground(Color.darkGray);
        frame.setSize(350, 350);    
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JTextField username = new JTextField();
        frame.add(username);
        frame.setVisible(true);
    }


}

The JFrame size works but the background does not and the TextField does not, pretty new to this. Any ideas? All help is appreciated.

Answer 1

The code works fine. The problem is that your text field takes up the entire frame. Try:

//frame.add(username);
frame.add(username, BorderLayout.NORTH);

Answer 2

The problem with your code is that your text field is covering the full jframe

one of the way is to reduce the text field size in the design view and then in code add this line

getContentPane().setBackground(Color.BLACK);