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NoClassDefFoundError using bluetooth in java

I asked a question earlier here: NoClassDefFoundError with bluecove's javax.microedition
but got no responses.
I am trying to run some java code (Server.java) that requires bluetooth, so I installed the bluecove-2.1.0.jar file in C:\Program Files\Java.
I compile my code with javac -cp "C:\Program Files\Java\bluecove-2.1.0.jar";. Server.java and run it with java Server -cp "C:\Program Files\Java\bluecove-2.1.0.jar"
It compiles successfully, but when I run it, I get the error:
Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.NoClassDefFoundError: javax/microedition/io/Connection
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Unknown Source)
at java.lang.Class.privateGetMethodRecursive(Unknown Source)
at java.lang.Class.getMethod0(Unknown Source)
at java.lang.Class.getMethod(Unknown Source)
at sun.launcher.LauncherHelper.validateMainClass(Unknown Source)
at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)
Caused by: java.lang.ClassNotFoundException: javax.microedition.io.Connection
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 7 more
Any ideas where i've gone wrong?
EDIT: Following Minus' answer, to fix the error that followed, I also needed to use a different .jar file which I downloaded from http://snapshot.bluecove.org/distribution/download/2.1.1-SNAPSHOT/2.1.1-SNAPSHOT.63/

The problem is that the .dll is not loaded correctly.
The library should contain a .dll that will be saved on disk and loaded, maybe the program cannot save the .dll to disk or cannot read it.
Extract the .dll and follow bluecove installation instructions on Native Library location.
For example:
Create a directory c:\blue, and a directory blue\lib.
Put the files like this:
C:\blue\Sever.java
C:\blue\Sever.class
C:\blue\[bluecove_native_library].dll
C:\blue\lib\bluecove-2.1.0.jar
Open a cmd (Command Prompt) on c:\blue
Try to run the app like this:
java -cp .;lib\bluecove-2.1.0.jar -Dbluecove.native.resource=false Server
This way you will have both Server.class and bluecove-2.1.0.jar in classpath and the DLL in path (since on Windows the current dir is in path).

Add a current folder to a classpath (.;) and make sure that your code is in a package-name folder.
So if your server has a package name :
mypackage
make sure that your class code is in a /mypackage directory
than go to a parent folder to /mypackage and call:
java -cp ".;C:\Program Files\Java\bluecove-2.1.0.jar" mypackage.Server

Problems exporting Jar using Weka

i've got a big problem exporting my project as a jar file (inside my project i use weka). I'm using Eclipse.
I've added in Java Build Path weka.jar and i've attached to it weka-src.jar, testing my classifier under eclipse everything works, so i've decided to create a jar (because i need that another program use it).
First of all i've created the manifest file:
Manifest-Version: 1.0
Rsrc-Class-Path: ./ weka.jar weka-src.jar
Class-Path: .
Rsrc-Main-Class: start.Home
Main-Class: start.Home
The main class of the program is Home (inside the package start), while weka.jar and weka-src.jar are inside the /src/ directory of the eclipse program.
When i try to execute the jar created i receive this output:
Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.NoClassDefFoundError: weka/classifiers/Classifier
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Unknown Source)
at java.lang.Class.privateGetMethodRecursive(Unknown Source)
at java.lang.Class.getMethod0(Unknown Source)
at java.lang.Class.getMethod(Unknown Source)
at sun.launcher.LauncherHelper.validateMainClass(Unknown Source)
at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)
Caused by: java.lang.ClassNotFoundException: weka.classifiers.Classifier
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 7 more
I think that the problem is the CLASSPATH so i've tried to solve it in this way:
I've created the Environment Variable CLASSPATH with this values:
C:\Users\tomma\Desktop\workspace Eclipse\AndroidPermissionsClassifier\src\weka.jar
C:\Users\tomma\Desktop\workspace Eclipse\AndroidPermissionsClassifier\src\weka-src.jar
but nothing changed, can someone help me please?

You are right: the classpath is the problem. Did you remove the items from the manifest classpath when you added them to the environment CLASSPATH? (Side note: place the source jar in the -sourcepath, not the classpath.)

MATLAB / Datafeed compiled code with Bloomberg APIv3 / Java library: Java Exception

Am trying to compile MATLAB code that employs Bloomberg's APIv3 via the Datafeed toolbox. The code runs fine within MATLAB. The compiler works fine on code without Java. The javaclasspath references the API via:
DYNAMIC JAVA PATH
C:\blpv3\API\APIv3\JavaAPI\v3.7.1.1\lib\blpapi3.jar
I get several compilation errors relating to Java (stacktrace below) on compilation with :
mcc -m -R -startmsg -R -completemsg -v my_prog.m
I suppose I need to tell mcc to link to blpapi3.jar more explicitly, but how? Do I need to set up a static Java path?
Any help would be much appreciated!
Warning: A Java exception occurred getting the method description for the
java.util.Locale class:
Java exception occurred:
java.lang.NoClassDefFoundError: com/bloomberglp/blpapi/Session
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Unknown Source)
at java.lang.Class.privateGetPublicMethods(Unknown Source)
at java.lang.Class.getMethods(Unknown Source)
at com.mathworks.jmi.OpaqueJavaInterface.doesMethodExist(OpaqueJavaInterface.java:407)
Caused by: java.lang.ClassNotFoundException: com.bloomberglp.blpapi.Session
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
... 5 more

After some more browsing and lots of trials, I have resolved the issue. The answers are in several posts on this site already. Anyway, there are several issues...
1
It appears that
Java exception occurred: java.lang.NoClassDefFoundError
is a runtime error, not a compile error. To fix this I updated the classpath.txt in both the COMPILER AND THE MCR, located at,
$matlabroot\toolbox\local\classpath.txt
to something like this
javaclasspath
STATIC JAVA PATH
C:\Program Files\MATLAB\R2012a\java\patch
C:\blpv3\API\APIv3\JavaAPI\v3.7.1.1\lib\blpapi3.jar
Alternatively, the blpapi3.jar can be copied into
$matlabroot/java/jarext
alongside the other JAR files.
Also, I removed the dynamic java path, which only works for the Matlab IDE.
2
I have disabled the ADDPATH in startup.m with a clause such as
if ~isdeployed && ~ismcc
addpath D:\Matlab
...
end
3
Arguments to mcc must include the directories in which the source files are located, i.e.
mcc -m -I 'source_file_dir' -v top_level_function.m
4
When handling files within the code, reference relative to the $matlabroot, e.g.
if isdeployed
sFile_Path = fullfile(matlabroot,'..','Input',sFile_Name);
else
sFile_Path = which(sFile_Name);
end
5
Notice that the $matlabroot of the MCR is different from the $matlabroot of the Matlab IDE.

How do I get started with JFreeChart?

I've never used any third party library before. What should I do after I downloaded jfreechart-1.0.14.tar.gz?
I don't know if I'm doing these things right:
1. Put the jcommon-1.0.17.jar and jfreechart-1.0.14.jar at the same directory as my source code.
2. Import needed class in the source code (e.g. import org.jfree.util.Rotation;)
Many articles tell you how to do this in IDEs. But instead of IDEs, I'm writing codes with vim and compile by myself. So, assume I didn't do any thing wrong, how should I compile the source code with javac and run the code with java?
Edit:
Here's my file layout:
./src
| - test.java
./lib
| - jcommon-1.0.17.jar
| - jfreechart-1.0.14.jar
I compile by
javac -cp "lib/*" -d classes/ src/test.java
then run by
java -cp classes:lib/jcommon-1.0.17.jar:jfreechart-1.0.14.jar test
However, some error occurs:
Exception in thread "main" java.lang.NoClassDefFoundError: org/jfree/data/general/PieDataset
How can I resolve this problem?
Exception in thread "main" java.lang.NoClassDefFoundError: org/jfree/data/general/PieDataset
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Unknown Source)
at java.lang.Class.getMethod0(Unknown Source)
at java.lang.Class.getMethod(Unknown Source)
at sun.launcher.LauncherHelper.getMainMethod(Unknown Source)
at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)
Caused by: java.lang.ClassNotFoundException: org.jfree.data.general.PieDataset
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 6 more

The libraries shouldn't be at the same place as the source code. If you don't want to use a build tool like Gradle yet, which would handle your library dependencies, then I suggest using the following layout:
project
src
.java files here, organized in a folder tree matching the package tree
classes
compiled .class files here
lib
.jar files here
To compile, go in the project directory and execute the following command:
javac -cp lib/jfreechart-1.0.14.jar:lib/jcommon-1.0.17.jar -d classes src/com/foo/bar/MyClass.java src/com/foo/bar/MyOtherClass.java
To run your app, execute the following command:
java -cp classes:lib/jfreechart-1.0.14.jar:lib/jcommon-1.0.17.jar com.foo.bar.MyClass

Java - Library path error

I'm trying to start my java game but I have some troubles with the java command line:
Here is what I type:
C:\>java -Djava.library.path=%cd%\lib -jar game.jar
And here is what I got:
Exception in thread "main" java.lang.NoClassDefFoundError: org/lwjgl/LWJGLException
at com.game.Main.main(Main.java:7)
Caused by: java.lang.ClassNotFoundException: org.lwjgl.LWJGLException
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 1 more
I can start my game with Eclipse (With Run as Java Application) but after the menu I got the following error:
Exception in thread "Thread-5" java.lang.UnsatisfiedLinkError: no lwjgl in java.library.path
at java.lang.ClassLoader.loadLibrary(Unknown Source)
at java.lang.Runtime.loadLibrary0(Unknown Source)
at java.lang.System.loadLibrary(Unknown Source)
at org.lwjgl.Sys$1.run(Sys.java:72)
at java.security.AccessController.doPrivileged(Native Method)
at org.lwjgl.Sys.doLoadLibrary(Sys.java:65)
at org.lwjgl.Sys.loadLibrary(Sys.java:81)
at org.lwjgl.Sys.<clinit>(Sys.java:98)
at org.lwjgl.opengl.Display.<clinit>(Display.java:129)
at com.game.displaygui.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
lwjgl.jar has been put into the folder \lib.
Could you explain me with I got that?
Thanks.

This because lwjgl library is made by two components:
the .jar file which contains Java code
and the native binary library (which can be .so or .dll or .dylib according to your OS)
The first error you are getting is because you are setting the library path, that should contain the native library, but it does contain the .jar. So you get a java.lang.NoClassDefFoundError because you should set either the library path to the folder that contains native library, either the classpath to contain the real lwjgl.jar file.
The second error that you get with Eclipse is a successive step: your classpath contains the jar library but it is not able to find the native library attached to it, you can fix it in the following way:

You should specify explicitly which lib files to include (seperated by ;) :
-cp %cd%\lib\lwjdl.jar;%cd%\lib\<another-lib>.jar
Don't be tempted to use the wildcard * as it will cause more harm than good (from previous experience :))

You use the java.library.path option to specify the location of native libraries to load. In the location pointed to by that option you would place all dll or .so files required by LWJGL. On the other hand, you need to make sure that all required JAR files are on your classpath, via the -classpath option. Currently, you have your JAR files in the wrong directory.

In Eclipse, if you using maven.
Add the following to the project "Run" : "VM options" .
-Djava.library.path=yourpath/youproject/java/target/natives