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Runtime error loading Interface definition in Java using Apache HTTP library

I am attempting to make a simple wrapper around an API connection in Java. I am using the org.apache.http library to do this.
I have downloaded the following jar files:
org.apache.http httpclient saved as ./org.apache.httpclient.jar
org.apache.http httpcore saved as ./org.apache.httpcore.jar
I can then successfully compile the file with:
$ javac -cp "./org.apache.httpclient.jar:./org.apache.httpcore.jar" Api.java
However when running it with $ java Api I receive:
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/http/HttpEntity
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Class.java:2625)
at java.lang.Class.getMethod0(Class.java:2866)
at java.lang.Class.getMethod(Class.java:1676)
at sun.launcher.LauncherHelper.getMainMethod(LauncherHelper.java:494)
at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:486)
Caused by: java.lang.ClassNotFoundException: org.apache.http.HttpEntity
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
... 6 more
[It turned out the issue was with how code was being run after compilation; the code has been removed to avoid distracting from the actual problem and solution]
I can't see why the system has a problem finding the HttpEntity interface when it finds other imports successfully, and can compile. If I remove any of the import lines compilation fails with unknown symbol errors.

-cp should contain the directory where you classes are, for example:
java -cp "./org.apache.httpclient.jar:./org.apache.httpcore.jar:." Api
Assuming that your Api.class is in the current directory. (replace : by ; as classpath separator if your are on a windows system)

Have you tried running the java with '-classpath'. While compiling you are giving the classpath, so you need to add the classpath option for running the class file as well.
More details can be found at below link:
http://docs.oracle.com/javase/7/docs/technotes/tools/windows/classpath.html
Also you can print which libs are in classpath using below command.
java -cp $(for i in lib/*.jar ; do echo -n $i: ; done). com.test.Class

Getting NoClassDefFoundError for an included jar

I'm writing a java app and running it on a linux ec2 server.
the program was running fluently yesterday, and after I changed and organazied some files and packages I'm getting this problem when I execute the program:
I'm running the programm with this command:
java -cp . main.Server
And get the following error:
Exception in thread "Thread-0" java.lang.NoClassDefFoundError: org/json/JSONObject
at main.Group.<init>(Group.java:28)
at main.Server.run(Server.java:23)
Caused by: java.lang.ClassNotFoundException: org.json.JSONObject
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
... 2 more
I was running the programm as this before the changes:
export CLASSPATH=$CLASSPATH:/home/ec2-user/java-json.jar
In the bin folder, command:
java Server
And the programm was running.
Since I changed the package from default name to main, I need to run it with the command java -cp . main.Server, but I get the error written above.
I also tried modifing the .bash_profile and add this:
CLASSPATH=$CLASSPATH:/home/ec2-user/java-json.jar
export CLASSPATH
But it didn't help.
I have no errors in my code and the jar is not broken since it worked before. What should I do to fix this problem?

Specify the jar file on the classpath like this:
java -cp .:/home/ec2-user/java-json.jar main.Server
If your classpath is indeed correctly set in your .bash_profile, you could also do:
java -cp .:$CLASSPATH main.Server

java not finding class in jar after successfully compiling with javac against same jar

I was looking at this question on stackoverflow and thought I'd try to run the benchmark myself. I downloaded caliper and compiled it successfully using maven. I then compiled HashCodeBenchmark from the linked question successfully using the jar that maven created. However, when I try to run HashCodeBenchmark, java complains that it cannot find a entrypoint class inside the jar.
I am utterly perplexed and have no idea what the problem is.
compile:
$ javac benchmark/HashCodeBenchmark.java \
-classpath caliper-1.0-beta-SNAPSHOT-all.jar \
&& echo success
success
run:
$ java benchmark.HashCodeBenchmark -classpath caliper-1.0-beta-SNAPSHOT-all.jar
Exception in thread "main" java.lang.NoClassDefFoundError: com/google/caliper/runner/CaliperMain
at benchmark.HashCodeBenchmark.main(HashCodeBenchmark.java:64)
Caused by: java.lang.ClassNotFoundException: com.google.caliper.runner.CaliperMain
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
... 1 more

You're providing the -classpath argument after the class name - so it's just being passed to your main method. You need to provide it before the class name, and include the current directory in the classpath too:
$ java -classpath caliper-1.0-beta-SNAPSHOT-all.jar:. benchmark.HashCodeBenchmark

java.lang.NoClassDefFoundError when using weka.jar file in my own java file

I'm having problems executing my java program. The code is placed in the file RunMining.java and contains multiple import weka.[..] lines. The weka library (weka.jar) is placed in the same folder.
I compile it:
$ javac -cp weka.jar RunMining.java
This creates three files: RunMining.class, RunMining$1.class, RunMining$classifierType.class
When i run it: java -cp weka.jar RunMining i get the following error:
Exception in thread "main" java.lang.NoClassDefFoundError: RunMining
Caused by: java.lang.ClassNotFoundException: RunMining
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
My RunMining.java file only contains one class called RunMining, which contains the main method. I would prefer not to add the weka.jar file to my CLASSPATH since this file will be compiled using a makefile and executed using a script, on different machines.
Any suggestions, to how i can run the compiled files?

You need to add the classpath of your compiled files as follows:
java -cp weka.jar;. RunMining
This assumes your files are compiled in the root directory which your javac command suggests.

SciTE: ClassNotFoundException in Java when using a newly added library (but not in command prompt)

I'm currently working with the Tidy class from the JTidy library provided by SourceForge (http://jtidy.sourceforge.net/).
I have already added the .jar library to the CLASSPATH, and I can compile the Java program in SciTE without any error. But when I try to run the program, SciTE prints out this output:
>java -cp . SourceViewer3
Exception in thread "main" java.lang.NoClassDefFoundError: org/w3c/tidy/Tidy
at SourceViewer3.main(SourceViewer3.java:65)
Caused by: java.lang.ClassNotFoundException: org.w3c.tidy.Tidy
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
... 1 more
>Exit code: 1
Note: line 65 is where I call the constructor of the Tidy class,
Tidy tidy = new Tidy();
But when I try to run the program in command prompt, it runs smoothly without any problem. How can I fix the problem in SciTE?
Additional information: I'm using Windows 7 64 bit, SciTE 3.0.3 and Java version "1.7.0_02".

Nevermind, it is solved now.
Turns out that I must run it by using the command "java (java class name)" rather than using the default command "java -cp . (java class name)" used by SciTE, so that it doesn't override the setting of the CLASSPATH environment variable.
Sorry for the bother ^^;;