Creating array of buttons

Question

I'm trying to create an array of buttons, but I keep getting a npe
Exception in thread "main" java.lang.NullPointerException
at java.awt.Container.addImpl<Container.java:1031>
at java.awt.Container.add<container.Java:352>
at ButtonArray.main<ButtonArray.java:26>
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ButtonArray{
static JLabel jl;
public static void main(String[] args){
JFrame jf = new JFrame();
JPanel p1 = new JPanel();
JPanel p2 = new JPanel();
jl = new JLabel();
int count = 30;
JButton[] jbh;
jbh = new JButton[count];
//JButton[] jbh = new JButton[]{new JButton("1"), new JButton("2")};
for(int x=1; x<count; x++) {
     jbh[x] = new JButton(Integer.toString(x));
Container c = jf.getContentPane();
for(int i = 0; i < jbh.length; ++i){
p1.add(jbh);
for(int i = 0; i < jbh.length; ++i){
jbh[i].addActionListener(new ButtonListener());
c.add(p1, BorderLayout.NORTH);
p2.add(jl);
c.add(p2, BorderLayout.SOUTH);
jf.setSize(400,300);
jf.setVisible(true);
jf.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent evt){
System.exit(0);
static class ButtonListener implements ActionListener{
public void actionPerformed(ActionEvent evt){
jl.setText("Button" + evt.getActionCommand() + " was pressed");

Answer 1

Just spotted the error.
Your for loop adding buttons to the array begins at 1. Therefore there is a null still in position 0 of your array which you attempt to access in your next for loop.
[shakes fist at Enc]
Edited by: flounder on Aug 7, 2009 11:08 AM