What's wrong with my Button?

Question

Hello everyone,
I been trying to get my Button working, but I don't understand what's wrong. I've tried a bunch of stuff, each with failure. Can any of you guys help me out here? I know that it's a little bit of a mess, but for some reason, it gives me a NullPointerException when I execute it. If I comment out 4 lines of code, about the getContentPane, it works without making a button. Problem is, I want to keep the Button in there. What should I do?
Thanks
frame.getContentPane().setLayout(new FlowLayout());
frame.getContentPane().add(startButton);
if (frame.getContentPane() instanceof JComponent)
     ((JComponent)frame.getContentPane()).setOpaque(false);
}

Answer 1

here is your original code, stripped of all the non-button parts
you will see that it does not generate a NPE
you may also note it is easy to read (code tags used)
suggestion - start again
start with a small section of code, ***compile/run/test/fix/compile/run/test
when all OK, add another section of code (repeat ***)
etc
etc
import java.awt.*;
import javax.swing.*;
class Graphic2
  public static void main(String[] args)
    new Graphic2().run();
  private JButton startButton;
  public void run()
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//added
    frame.setLocation(400,300);//added
    startButton = createButton("Start.gif");
    startButton.setLocation(460, 500);
    frame.getContentPane().setLayout(new FlowLayout());
    frame.getContentPane().add(startButton);
    frame.pack();//added
    frame.setVisible(true);//added
  public JButton createButton(String name)
    String imagePath = name;
    ImageIcon iconRollover = new ImageIcon(imagePath);
    int w = iconRollover.getIconWidth();
    int h = iconRollover.getIconHeight();
    Cursor cursor = Cursor.getPredefinedCursor(Cursor.HAND_CURSOR);
    // create the button
    JButton button = new JButton("btn");//added "btn"
    //button.addActionListener(this);
    button.setIgnoreRepaint(true);
    button.setFocusable(false);
    button.setBorder(null);
    button.setContentAreaFilled(false);
    button.setCursor(cursor);
    button.setIcon(iconRollover);
    button.setRolloverIcon(iconRollover);
    button.setPressedIcon(iconRollover);
    return button;
}