Java GUI Static component, NullPointerException

[AlarV]

Hey everyone, I created a GUI project, where I'm using a JTree. When it's created everything is ok, but in my run() method when I call it i get a nullPointerException. Here is the code.

treePanel = new javax.swing.JPanel();
DefaultMutableTreeNode top =
        new DefaultMutableTreeNode("blah");
        mytree = new javax.swing.JTree(top);
javax.swing.GroupLayout treePanelLayout = new javax.swing.GroupLayout(treePanel);
        treePanel.setLayout(treePanelLayout);
        treePanelLayout.setHorizontalGroup(
            treePanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, treePanelLayout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 138, Short.MAX_VALUE)
        );
        treePanelLayout.setVerticalGroup(
            treePanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, treePanelLayout.createSequentialGroup()
                .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 277, Short.MAX_VALUE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
        );
 

of course I add stuff to the tree, but i'm not showing it here cause it's part of the project and personal data.

and in run() method

mPanel= new JPanel();
mPanel.setLayout(new BoxLayout(mPanel,BoxLayout.X_AXIS));
mPanel.add(treePanel);
 

and the declaration of my variables

    // Variables declaration - do not modify
    private javax.swing.JComboBox jComboBox1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTree mytree;
    private javax.swing.JPanel treePanel;
    // End of variables declaration
 

[horace1]

when you get the exception does it tell you which line in the code it is on?

[AlarV]

well yeah it says:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at charybdis.Main$2.run(Main.java:260)
and it is this line

mPanel.add(treePanel);

[horace1]

it looks like treePanel does not reference a JPanel object hence you get a NullPointerException
have you a

treePanel=new JPanel();
 

in your code ? is it before you call the run() method ?

[AlarV]

yes it's on line 1 in the first code tag!

[horace1]

looks like you have not executed that code before you call the run() method
as a quick test try in the declarations

private javax.swing.JPanel treePanel = new javax.swing.JPanel();
 

[AlarV]

well the main program has this method

public Main() {
        initComponents();
    }

and then in initComponents it does all the work I posted. then there is this

public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
 
            public void run() {
                try {

and that's where I add the panel to the main frame.

I can't try what you suggested because the variable declaration part is locked and I can't add stuff!
If the code isn't executed the problem is why, as the initComponents runs even before the main() method..

[horace1]

when do you call method Main() ?
try calling initComponents(); in main() before you call run() ?

[AlarV]

I can't cause of the classic bull#*$@#* of java.

initComponents isn't static and I can't call it in static main..

I tried what you suggested before though.
treePanel=new JPanel(); before run() and it worked!
this means that initComponents doesn't run, so I'll have to check this out.

If you have any ideas why initComponents is not working you are more than welcome to tell them. I'm stuck at this for like 2 days..

[horace1]

it is difficult not being able to see all the code

is your main() method in a class call Main?
if so could you do

public static void main(String args[]) {
   Main x = new Main();
 

to create an instance of Main which would call initComponents();

[AlarV]

sorry for the delay.. you are right! that was the problem I thought that as it was in the class it ran alone, but you have to call it in main.

Thanx!