Error Msg

[ivy]

Hi there,
I got some problems running my program.

what is the meaning of this error??

Exception in thread "main" java.lang.NullPointerException
at java.awt.Container.addImpl(Unknown Source)
at java.awt.Container.add(Unknown Source)
at fyp.Firstpage.getJPanel(Firstpage.java:95)
at fyp.coverpage.getJDesktopPane(coverpage.java:65)
at fyp.coverpage.getJContentPane(coverpage.java:48)
at fyp.coverpage.getJFrame(coverpage.java:31)
at fyp.coverpage.main(coverpage.java:72)

I cant run my program.

[Aseem]

This means, you are value of a particular variable is null and it is not supposed to be null.
check the condition for null. For e.g if(something!=null){
}

[ivy]

Hi there, i dunno which one to change. Can you kindly help me check???


import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Toolkit;

import javax.swing.JDesktopPane;
import java.awt.Rectangle;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import java.awt.SystemColor;
import javax.swing.JLabel;
public class coverpage {

private JFrame jFrame = null; // @jve:decl-index=0:visual-constraint="351,91"
private JPanel jContentPane = null;
private JDesktopPane jDesktopPane = null;


/**
* This method initializes jFrame
*
* @return javax.swing.JFrame
*/
private JFrame getJFrame() {
if (jFrame == null) {
jFrame = new JFrame();
jFrame.setTitle("Coverpage");
jFrame.setContentPane(getJContentPane());
Dimension screenSize= Toolkit.getDefaultToolkit().getScreenSize();
jFrame.setSize(screenSize.width,screenSize.height) ;
jFrame.validate();
}
return jFrame;
}

/**
* This method initializes jContentPane
*
* @return javax.swing.JPanel
*/
private JPanel getJContentPane() {
if (jContentPane == null) {
jContentPane = new JPanel();
jContentPane.setLayout(new BorderLayout());
jContentPane.add(getJDesktopPane(),BorderLayout.CE NTER);
}
return jContentPane;
}

/**
* This method initializes jDesktopPane
*
* @return javax.swing.JDesktopPane
*/

public JDesktopPane getJDesktopPane(){
if(jDesktopPane ==null){
jDesktopPane = new JDesktopPane();
jDesktopPane.setLayout(new BorderLayout());
Firstpage homepage = new Firstpage(coverpage.this);
jDesktopPane.removeAll();
jDesktopPane.add(homepage.getJPanel(),BorderLayout .CENTER);
}
return jDesktopPane;
}

public static void main(String[] args){
coverpage frame = new coverpage();
frame.getJFrame().setVisible(true);
}

}

[Tolls]

Considering the error is occurring somewhere below here:
at fyp.Firstpage.getJPanel(Firstpage.java:95)
you haven't shown us the FirstPage code.

You should also highlight the line involved.

And use code tags.

[ivy]

This is my Firstpage code. But i cant find tat code that you are referring to.
.................................................. .................................................. ...

package fyp;

import javax.swing.ImageIcon;
import javax.swing.JPanel;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.Rectangle;
import javax.swing.JLabel;
import java.awt.Color;
import javax.swing.JTextField;

public class Firstpage {

coverpage home = null;
private JPanel jPanel = null; // @jve:decl-index=0:visual-constraint="39,16"
private JLabel jLabel = null;
private JLabel jLabel1 = null;
private JLabel jLabel11 = null;
private JLabel jLabel12 = null;
private JLabel jLabel13 = null;
private JLabel jLabel14 = null;
private JLabel jLabel15 = null;
private JTextField jTextField = null;
private JTextField jTextField1 = null;
private JTextField jTextField2 = null;
private JTextField jTextField3 = null;
private JLabel jLabel16 = null;
private JTextField jTextField4 = null;
public Firstpage(coverpage home){
this.home = home;
}

/**
* This method initializes jPanel
*
* @return javax.swing.JPanel
*/
JPanel getJPanel() {
if (jPanel == null) {
jLabel16 = new JLabel();
jLabel16.setBounds(new Rectangle(1008, 634, 266, 71));
jLabel16.setText("");
jLabel16.setIcon(new ImageIcon(getClass().getResource(
"/coverpage_PIC/printiticon.jpg")));
jLabel15 = new JLabel();
jLabel15.setBounds(new Rectangle(1010, 508, 264, 73));
jLabel15.setText("");
jLabel15.setIcon(new ImageIcon(getClass().getResource(
"/coverpage_PIC/helpicon.jpg")));
jLabel14 = new JLabel();
jLabel14.setBounds(new Rectangle(1003, 372, 272, 78));
jLabel14.setText("");
jLabel14.setIcon(new ImageIcon(getClass().getResource(
"/coverpage_PIC/tutorialsicon.jpg")));
jLabel13 = new JLabel();
jLabel13.setBounds(new Rectangle(1011, 240, 265, 75));
jLabel13.setText("");
jLabel13.setIcon(new ImageIcon(getClass().getResource(
"/coverpage_PIC/theoryicon.jpg")));
jLabel12 = new JLabel();
jLabel12.setBounds(new Rectangle(1008, -1, 267, 177));
jLabel12.setText("");
jLabel12.setIcon(new ImageIcon(getClass().getResource(
"/coverpage_PIC/normalstresswords.jpg")));
jLabel11 = new JLabel();
jLabel11.setBounds(new Rectangle(1, 1, 100, 748));
jLabel11.setText("");
jLabel11.setIcon(new ImageIcon(getClass().getResource(
"/coverpage_PIC/wordMOM.jpg")));
jLabel = new JLabel();
jLabel.setBounds(new Rectangle(100, 1, 910, 748));
jLabel.setText("");
jLabel.setIcon(new ImageIcon(getClass().getResource(
"/coverpage_PIC/bay-bridge.jpg")));
GridBagConstraints gridBagConstraints = new GridBagConstraints();
gridBagConstraints.gridx = 0;
gridBagConstraints.gridy = 0;
jPanel = new JPanel();
jPanel.setLayout(null);
jPanel.setSize(new Dimension(1275, 750));
jPanel.add(jLabel, null);
jPanel.add(jLabel11, null);
jPanel.add(jLabel12, null);
jPanel.add(jLabel13, null);
jPanel.add(jLabel14, null);
jPanel.add(jLabel15, null);
jPanel.add(getJTextField(), null);
jPanel.add(getJTextField1(), null);
jPanel.add(getJTextField2(), null);
jPanel.add(getJTextField3(), null);
jPanel.add(jLabel16, null);
jPanel.add(getJTextField4(), null);
jPanel.add(jLabel1, null);

}
return jPanel;
}

/**
* This method initializes jTextField
*
* @return javax.swing.JTextField
*/
private JTextField getJTextField() {
if (jTextField == null) {
jTextField = new JTextField();
jTextField.setBounds(new Rectangle(1005, 175, 270, 66));
jTextField.setBackground(new Color(102, 0, 0));
}
return jTextField;
}

/**
* This method initializes jTextField1
*
* @return javax.swing.JTextField
*/
private JTextField getJTextField1() {
if (jTextField1 == null) {
jTextField1 = new JTextField();
jTextField1.setBounds(new Rectangle(1003, 312, 274, 62));
jTextField1.setBackground(new Color(102, 0, 0));
}
return jTextField1;
}

/**
* This method initializes jTextField2
*
* @return javax.swing.JTextField
*/
private JTextField getJTextField2() {
if (jTextField2 == null) {
jTextField2 = new JTextField();
jTextField2.setBounds(new Rectangle(1003, 451, 272, 58));
jTextField2.setBackground(new Color(102, 0, 0));
}
return jTextField2;
}

/**
* This method initializes jTextField3
*
* @return javax.swing.JTextField
*/
private JTextField getJTextField3() {
if (jTextField3 == null) {
jTextField3 = new JTextField();
jTextField3.setBounds(new Rectangle(1002, 580, 272, 56));
jTextField3.setBackground(new Color(102, 0, 0));
}
return jTextField3;
}

/**
* This method initializes jTextField4
*
* @return javax.swing.JTextField
*/
private JTextField getJTextField4() {
if (jTextField4 == null) {
jTextField4 = new JTextField();
jTextField4.setBounds(new Rectangle(1002, 704, 272, 46));
jTextField4.setBackground(new Color(102, 0, 0));
}
return jTextField4;
}

}

[Tolls]

Which line is line 95?
That's what the stack trace means...(Firstpage.java:95)...line 95 in FirstPage.java.