Problem on aboutBox() in java - netbeans

Question

I'm developing a javadesktop application in Netbeans 6.9 and everything is perfect but...it gives me an error on this :
#Action
public void showAboutBox()
{
if (aboutBox == null) {
JFrame mainFrame = Mp4App.getApplication().getMainFrame();
aboutBox = new mp4AboutBox(mainFrame);
aboutBox.setLocationRelativeTo(mainFrame);
}
}
/** This method is called from within the constructor to
* initialize the form.
* WARNING: Do NOT modify this code. The content of this method is
* always regenerated by the Form Editor.
*/
#SuppressWarnings("unchecked")
and this is the error :
Compiling 1 source file to Q:\Mp3 App\mp4-beta\mp4\build\classes
Q:\Mp3 App\mp4-beta\mp4\src\mp4\Mp4View.java:223: cannot find symbol
symbol : class mp4AboutBox
location: class mp4.Mp4View
aboutBox = new mp4AboutBox(mainFrame);
1 error
Q:\Mp3 App\mp4-beta\mp4\nbproject\build-impl.xml:603:
The following error occurred while executing this line:
Q:\Mp3 App\mp4-beta\mp4\nbproject\build-impl.xml:284: Compile failed; see the compiler error output for details.
BUILD FAILED (total time: 8 seconds)
the real problem is that this is the code generated from netbeans...also if you create a new Project->java->Destop Application and you leave it there without adding nothing,it gives always me the same problem... what to do ????????????
netbeans version: 6.9.1
jdk version: 7
O.S : Windows 7 32 bit

Answer 1

You shouldn't create your GUI using Netbeans because it generates unreadable code. The Swing-Package is pretty straight forward, so you should use it.
To the Error: Do you have a mp4AboutBox-class and what is in it?

Answer 2

You might be missing an import. Provide your imports in that file.

Answer 3

I had a similar question that I got the solution to by re-installing netbeans 6.9.1.
This is the solution I came up with from that:
TestProject class:
import org.jdesktop.application.Application;
import org.jdesktop.application.SingleFrameApplication;
public class TestProject extends SingleFrameApplication {
#Override protected void startup() {
show(new AppView(this));
}
#Override protected void configureWindow(java.awt.Window root) { }
public static TestProject getApplication() {
return Application.getInstance(TestProject.class);
}
public static void main(String[] args) {
launch(TestProject.class, args);
}
}
AppView JFrame:
import org.jdesktop.application.FrameView;
import org.jdesktop.application.SingleFrameApplication;
public class AppView extends FrameView {
public AppView(SingleFrameApplication app) {
super(app);
JFrame mainFrame = TestProject.getApplication().getMainFrame();
AboutBox newAboutBox = new AboutBox();
newAboutBox.setLocationRelativeTo(mainFrame);
TestProject.getApplication().show(newAboutBox);
}
}