Java Question Class not found in 3rd party lib

I am writing a library for B4A and it uses another library from a third party. I was happy to get a stack trace from my library in the B4A log that said there was a class not found exception in the third-party library. If I look at the jar with 7-Zip I created and placed in Additional Libs, it is in the libs folder of the jar. Am I missing a class path entry that should be in the libraries xml from the doclet, or somewhere else?

Stack trace:
button clicked
exception on create reader: java.lang.NoClassDefFoundError: IDTech.MSR.uniMag.uniMagReaderHelper
at IDTech.MSR.uniMag.uniMagReader.<init>(uniMagReader .java:18)
at com.dsi.b4a.epay.ClientAction.createReader(ClientA ction.java:75)
at KCSoft.TestLayout.main._button1_click(main.java:31 3)
at java.lang.reflect.Method.invokeNative(Native Method)


It almost looks like B4A finds the uniMagReader in the external jar, but the uniMagReader cannot find the uniMagReaderHelper which is inside the jar. Is that a likely understanding?

Is this library supported by Android?

This thread may be of interest: http://www.b4x.com/forum/libraries-developers-questions/17767-referncing-wrapped-libs.html.

I've found that getting Eclipse to package an additional .jar file into a compiled library is tricky.
Much easier to add the DependsOn annotation to your library class and then require that the additional .jar file be located in the B4A additional libraries folder.

This has the advantage that if the additional .jar file gets updated then it can be replaced in the B4A additional libraries folder with no need to recompile your B4A library.

Martin.

Erel said:

Is this library supported by Android?

Click to expand...

yes, for sure.

As warwound wrote you should use @DependsOn to tell the IDE to reference the jar file. You do not need to include the original jar file in your jar (it is possible but not in the way you did it).

Thanks for the help. I am trying suggestions.

I modified the my Eclipse project so that it does not put the 3rd party lib in the jar when it is created. I did this by un-checking the lib checkbox in the JAR File Specification dialog. I looked at the jar that was created:

C:\Program Files (x86)\Anywhere Software\Basic4android\AdditionalLibs>jar -tf NccEpayClient.jar
META-INF/MANIFEST.MF
NccEpayClient.xml
com/dsi/b4a/epay/ErrCodes.class
com/dsi/b4a/epay/TranResponse.class
com/dsi/b4a/epay/DsiParser.class
com/dsi/b4a/epay/ClientAction$TranType.class
com/dsi/b4a/epay/ClientAction.class
.classpath
.project

At the end of the NccEpayClient.xml produced by the doclet I see depends:

<dependsOn>IDTuniMagSDKAndroid</dependsOn>

In my additional lib folder I just have

01/28/2013 11:40 AM <DIR> ..
04/11/2012 04:28 PM 142,472 IDTuniMagSDKAndroid.jar
01/28/2013 11:36 AM 31,638 NccEpayClient.jar
01/28/2013 11:38 AM 10,040 NccEpayClient.xml

** Activity (main) Create, isFirst = true **


However I still get the class not found exception.

exception on create reader: java.lang.NoClassDefFoundError: IDTech.MSR.uniMag.uniMagReaderHelper


at IDTech.MSR.uniMag.uniMagReader.<init>(uniMagReader.java:18)
at com.dsi.b4a.epay.ClientAction.createReader(ClientAction.java:75)
FAILED reader

Any thoughts for me?

If you open the IDTuniMagSDKAndroid.jar (with say WinRAR) can you find any class files for the IDTech.MSR.uniMag.uniMagReaderHelper class?

Martin.

cannot find class inside 3rd party lib

Still a mystery. I used the AbsObjectWrapper just to see if I could get past the class not found. My jar is as simple as they get:

package com.dsi.b4a.unimag;

import IDTech.MSR.uniMag.uniMagReader;
import anywheresoftware.b4a.AbsObjectWrapper;
import anywheresoftware.b4a.BA;
import anywheresoftware.b4a.BA.DependsOn;
import anywheresoftware.b4a.BA.ShortName;
import anywheresoftware.b4a.BA.Version;

@DependsOn(values = { "IDTuniMagSDKAndroid" })
@ShortName("uniMagReader")
@Version(0.01f)
public class unimagWrapper extends AbsObjectWrapper<IDTech.MSR.uniMag.uniMagReader> {
public void initialize(BA pBA) {
setObject(new uniMagReader(null, pBA.context));
}
}

I declare a uniMagReader in Sub Globals and call initialize in the Activity_Create. The log shows:

** Activity (main) Create, isFirst = true **


main_activity_create (java line: 230)


java.lang.NoClassDefFoundError: IDTech.MSR.uniMag.uniMagReaderHelper
at IDTech.MSR.uniMag.uniMagReader.<init>(uniMagReader.java:18)
at com.dsi.b4a.unimag.unimagWrapper.initialize(unimagWrapper.java:15)
at b4a.example.main._activity_create(main.java:230)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
....

Looking at the IDTuniMagSDKAndroid.jar in Additional Libraries I clearly see UniMagReader and UniMagReaderHelper.

Can you upload your library?

uploaded 3rd party library

Erel, this is the third party library where the class is not found

Please also upload your library (and xml file).

Sorry for delay - this jar has classes it cannot find

Here is the third party jar file that results in the class not found error.

wrapper lib and xml

Here is the wrapper project and its XML file

The error message might be wrong. Are you sure that you can pass null as the first parameter?

Another question, maybe the context should be an activity context? You can add @ActivityObject to the class.