Cómo cambiar el color de fondo jframe
mainFrame.getContentPane().setBackground(Color.CYAN);
Tough Tern
mainFrame.getContentPane().setBackground(Color.CYAN);getContentPane().setBackground(Color.YELLOW); //Whatever colorpackage Exaple;
import java.awt.Color;
import javax.swing.JFrame;
public class Window {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.setVisible(true);
frame.setTitle("Expaple");
frame.setBackground(Color.BLUE);