Error Message At Runtime

Question

I want to include javahelp into my standalone application where I want to use menu driven general purpose help. I have written the following code.
     HelpSet hs;
     HelpBroker hb = null;
     try
     URL hsURL =
new URL((new File(".")).toURL, "./help/BeHelp.hs");
System.out.println(hsURL);
     hs = new HelpSet(null,hsURL);
     hb = hs.createHelpBroker();
     hb.setHelpSet(hs);
     catch (Exception ex)
     menuItem = new JMenuItem("ANT Help");
     menu.add(menuItem);
     menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_H, ActionEvent.CTRL_MASK));
     menuItem.addActionListener(new CSH.DisplayHelpFromSource(hb));
     The program compiles without any errors.However, when I execute
the program, I get the following runtime error:
     file:/E:/BuildEssentials/dist/help/BeHelp.hs
     Exception in thread "main" java.lang.NoClassDefFoundError: javax/help/HelpSet
     at base.uid.BuildEssentials.setMenu(Unknown Source)
     at base.uid.BuildEssentials.<init>(Unknown Source)
at base.uid.BuildEssentials.main(Unknown Source)
     From the output it is clear that the program is able to find
the URL of the helpset file correctly. The error is occuring in
the following line of code
     hs = new HelpSet(null,hsURL);
I have included jhall.jar in my classpath. The java command is as follows:
java -classpath ".;.\lib\jhall.jar" -jar BuildEssentials.jar
What is possibly going wrong? I have checked the helpset in the hsviewer utility and it works fine.

Answer 1

Your error suggests that the "HelpSet" class is not found.
Which means that jh.jar is not available to the classloader.
Because you are running your main application via the "java -jar myjar.jar" method - it may be that this uses a different classloader and therefore you may need to specify a CLASS PATH entry in the Manifest.mf file of your JAR to reference the jh.jar.
Add this line into your Manifest.mf, and ensure jh.jar is in your working directory (same as your application jar).
"Class-Path: jh.jar "
A quick way to test if you have classloader problem is to put the jh.jar on the bootclasspath using (java -Xbootclasspath/a:jh.jar). Recommended only to test if this is the problem.
I want to include javahelp into my standalone
application where I want to use menu driven general
purpose help. I have written the following code.
     HelpSet hs;
     HelpBroker hb = null;
     try
     URL hsURL =
new URL((new File(".")).toURL,
".")).toURL, "./help/BeHelp.hs");
System.out.println(hsURL);
     hs = new HelpSet(null,hsURL);
     hb = hs.createHelpBroker();
     hb.setHelpSet(hs);
     catch (Exception ex)
     menuItem = new JMenuItem("ANT Help");
     menu.add(menuItem);
     menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEven
.VK_H, ActionEvent.CTRL_MASK));
menuItem.addActionListener(new
CSH.DisplayHelpFromSource(hb));
The program compiles without any errors.However, when
I execute
the program, I get the following runtime
runtime error:
     file:/E:/BuildEssentials/dist/help/BeHelp.hs
Exception in thread "main"
java.lang.NoClassDefFoundError: javax/help/HelpSet
at base.uid.BuildEssentials.setMenu(Unknown
(Unknown Source)
at base.uid.BuildEssentials.<init>(Unknown
(Unknown Source)
at
at base.uid.BuildEssentials.main(Unknown
main(Unknown Source)
From the output it is clear that the program is able
to find
the URL of the helpset file correctly. The
ly. The error is occuring in
the following line of code
     hs = new HelpSet(null,hsURL);
I have included jhall.jar in my classpath. The
h. The java command is as follows:
java -classpath ".;.\lib\jhall.jar" -jar
" -jar BuildEssentials.jar
What is possibly going wrong? I have checked
hecked the helpset in the hsviewer utility and it
works fine.