Develop Reference

Trouble Understanding/Locating a Jar file (JIDT package) needed for Octave to Java Array Conversion

In this previous question, I was trying to rework some Matlab code and figure out a package called javaplex to be compatible with Octave; it uses Java, but is tooled for Matlab, hence that issue. Now in an interval of time, I was busy/running simulations, and hadn't gotten around to a final step - actually using the package, with most all of the difficulties worked out. It turns out that another step exists: I need to convert an Octave array to a Java array (although I'm not sure why this issue didn't come up in Matlab).
To do so, I have turned to this script, in which the comments indicate that when using it, it
Assumes the JIDT [Java Information Dynamics Toolkit] jar is already on the java classpath - you will get a java classpath error if this is not the case.
So I go to the JIDT GitHub page and download this package. Now I am not a very avid user of java, so I believe I am failing to see something fairly straightforward: I am not sure where the "JIDT jar" is that is referenced in the above block quote! I can't find such a particular jar file to put in Octave's java classpath. In this tutorial for JIDT, they say you need the "infodynamics.jar" file in the classpath (page 9). I'm not sure what jar file I should be looking for, and where. Any help understanding the nature, name and location of this jar file (within the infodynamics toolkit folder) would be appreciated!
As an inevitable follow-up question, because this will come up upon resolving this issue, I would like to clarify the following procedure is how to add a jar file to the Octave (static) java classpath (following this answer here, I wasn't sure if I was implementing correctly):
I create a file called "javaclasspath.txt" inside of the directory I use in Octave.
I enter the name of files as follows: "./path/to/your-file.jar"
I suppose my main issue here is where do I start the path (all the way back with "C:/..."?), and do I put this "javaclasspath.txt" file in the directory folder I will be using most of the time in Octave?
Edit: I cannot find "infodynamics.jar" as shown here:

The JIDT jar is named infodynamics.jar and it is located in the root of the downloads infodynamics-dist-1.4.zip file.

Factual API and coldfusion

I took the java implementation of the Factual API (reference http://developer.factual.com/) and made a JAR file for factual. I did this by opening a new project in eclipse with the factual java files and then exporting to a new jar file.
I put that jar file in my coldfusion installation's /WEB-INF/lib/ folder.
After restarting Coldfusion, I tried to create a new cfobject like so
<cfscript>
// Initialize the Java class.
factualClass=CreateObject("java", "src.main.java.com.factual.driver.Factual");
</cfscript>
I get an error indicating that it cannot find the Factual class.
Can anybody give me some guidance?

(Summary from comments)
It sounds like you may be exporting the source files ie *.java rather than the compiled class files, ie *.class. In the Jar Export wizard, be sure to select the "Export generated class files and resources" option. (To automatically compile the project sources before expi, enable the setting: JAR packaging > Build projects if not build automatically option). If you prefer you can also find pre-compiled jars in the MVN repository.
put that jar file in my coldfusion installation's /WEB-INF/lib/
folder.
CF10+ also supports dynamic class loading via a new application level setting THIS.javaSettings.
// Initialize the Java class.
factualClass=CreateObject("java", "src.main.java.com.factual.driver.Factual");
Just as a point of interest, src/main/java/ is not actually part of the libary class name. It is a standard directory structure used in Maven projects. It is probably included when exporting the sources, but not the compiled classes.
You can always verify the correct path and class name either by examining the API ie javadocs or by viewing one the source files. Package declarations are always at the top of the source file, such as on line 1 of src/main/java/com/factual/driver/Factual.java:
package com.factual.driver; // ie "com.factual.driver"
.. and the class declaration on line 39.
public class Factual { // ie "Factual"
Combined that gives you the exact (case-sensitive) path to use with createObject:
factualClass=CreateObject("java", "com.factual.driver.Factual");

Package does not exist error when package was added to classpath

Note, linked solutions (ex. Fatal Error: Unable to find package java.lang in classpath or bootclasspath) do not work.
I get this error, but the package is imported (commons... .jar)
org.apache.commons.lang3.tuple //does not exist import
org.apache.commons.lang3.tuple.MutableTriple
Source code
import org.apache.commons.lang3.tuple.MutableTriple;
import org.apache.commons.lang3.tuple.Pair;
import org.apache.commons.lang3.tuple.Triple;
Build code:
export
JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_25.jdk/Contents/Home
/Library/Java/JavaVirtualMachines/jdk1.8.0_25.jdk/Contents/Home/bin/javac
-target 1.8 -source 1.8 -classpath \ "../lib/commons-lang3-3.4.jar;../lib/httpclient-4.5.jar;../lib/httpcore-4.4.1.jar;../lib/org.json-20120521.jar;../lib/pdfbox-app-2.0.0-20150606.170503-1383.jar;../src/:../lib/commons-lang3-3.4-javadoc.jar;../lib/pdfbox-app-2.0.0-20150606.170503-1383-sources.jar" \ -d output \ ../src/com/tymaf/pdf/*.java
How to fix this problem?

Double check your classpath. Looks like you mixed delimiters ; and :.
Also instead of including jar with compiled classes (library itself). You've included java-docs and sources that are useless in classpath.
../src/:
../lib/commons-lang3-3.4-javadoc.jar;
../lib/pdfbox-app-2.0.0-20150606.170503-1383-sources.jar

Here is my suggestion
How to compile and use .jar extension
.jar extension can be imported different ways depending on your environment and IDE.
Here how it work as native mode from console.
Download the .jar.zip library from
http://www.java2s.com/Code/Jar/c/Downloadcommonslang333jar.htm
Create a folder in your working (project) directory call it libs
Unzip the downloaded file and copy commons-lang3-3.3.jar to your working directory libs
I have also created a class just for testing call it TheNewWork.java and added the 3 imports.
Now from your working directory c:\projects for Compile:
javac -classpath "/Projects/libs/commons-lang3-3.3.jar;" TheNewWork.java
And for running it:
java -classpath "/Projects/libs/commons-lang3-3.3.jar;" TheNewWork
If you have more than one .jar just add ; for Windows and : for Linux. Btw I use windows 10 cmder console and java jdk1.8.0_66. In other OS console you might need to put .:Projects...etc in stead of /Projects...etc. but the idea is the same.
UPDATE
In windows it is possible to set classpath like
set CLASSPATH=%CLASSPATH%;C:\Projects\libs\commons-lang3-3.3.jar
OR in Linux
export CLASSPATH=".:/Projects/libs/commons-lang3-3.3.jar"
Then you can run javac TheNewWork.java but it is personal taste to do it this or the other way. Some things similar is also possible to do in other OS.
Last thing, if you lazy and do neither want to write a full command line nor create a classpath, you could create a batch file with the full command line and run it that way in stead ;)
Some references:
http://docs.oracle.com/javase/8/docs/technotes/tools/windows/classpath.html
https://www3.ntu.edu.sg/home/ehchua/programming/howto/JDK_Howto.html
https://www.chilkatsoft.com/java-classpath-Windows.asp
I hope this solves your problem
Before the solution
After the solution
NOTE
In addition thanks to #MarkPeters notified me on my previous answer: Adding application dependencies directly to the JRE libs is not a good approach, as it makes the JRE suitable for running only one Java application, rather than being a generic runtime. Plus it would complicate whatever deployment the OP wants to do. lib/ext is made for extending the core Java APIs, as described here: docs.oracle.com/javase/tutorial/ext/basics/install.html. Not for normal application dependencies.

NoClassDefFoundError when runnable jar

Hi Guys I have included the Webcam-Capture API in my project.
When I run it in Netbeans everything works fine. But when i compile everything to a runnable jar i get this message trying to run it by cmd line.
can anyone of you help me?
i already tried to unbound and rebound all jars and changing jdks but its not working

add -classpath flag in the command line ,pointing to the path where Webcam-Capture API exists in your file system, unless you want to create a single package executable.In your case It should be something like below
java -classpath YOURJAR.jar;folder_of_dependant_jar/*;. com.awesome.pagackage.Starter
Where YOURJAR.jar contains the com.awesome.pagackage.Starter.main(String args[])
You also mentioned that your jar is a runnable jar it also means that while exporting/building you can do one of the following way.( NOTE , this feature is in eclipse , but you would get the idea ).Each of the following options you see in the library handling does specific things.
The first option: Extracts the dependent jar into your target jar as java packaging.This means if your package is com.awesome.package and the dependent jar has package logic.package; , after the runnable jar is build you could find both these package exists in your jar file.
The second option: I think it is more on eclipse specific since eclipse adds few classes of its own , of runnable generation, so I am not explaining it here.
The third option : is the most interesting one. it creates folder stucture like below
ndon_lib\external.jar ( external jar file )
ndon.jar ( your jar file )
This time the manifest.mf file contains something like below.
Class-Path: . ndon_lib/external.jar
Main-Class: com.awesome.pagackage.Starter

You should set the classpath
java -cp "your.jar" "yourclass"

Add a new class to an existing JAR File(which contains source code)

I'll try to illustrate the problem as simple as I can.
I have a JAR file, which I extracted using Winrar. (The jar file contains an open source android library).
I want to modify this JAR file by adding a new class to the library.
So here are my steps:
First, I created a class using Eclipse and set the package name same as the android's library package name.
Second, I copied this java File to the folder of the other java files in the library.
Third, I tried to compile the JAVA file via the CMD using javac.
The path of the new java file and the other .JAVA and .CLASS files of the library is: C:\com\example\core\
The name of the new java file would be: "MyNewClass.java"
The command I run via the CMD is: javac C:\com\example\core\MyNewClass.java
But, during the compilation I get many errors saying: Cannot find symbols.
I've been looking up for a solution of this problem but couldn't figure how to solve it and make the new JAR File having another class that I created seperately.
What am I missing?

As per earlier comments:
Rather than trying to modify the JAR, you can get access to the full source code of the Universal Image Loader library by cloning the repository using git or hitting "Download ZIP" on the righthand side of the page you linked.
Once you have the source, import the library in your IDE. From there on you'll be able to build the whole thing from scratch, make any adjustments/modifications you like, etc.

Your classpath might be wrong or there might be some mistake in package name.
When a Java program is being compiled the compiler it creates a list of all the identifiers in use. If it can't find what an identifier refers to it cannot complete the compilation. This is what the cannot find symbol error message is saying, it doesn't have enough information to piece together what the Java code wants to execute.

Try:
javac -cp com/* C:\com\example\core\MyNewClass.java
That should make the compiler aware of all the other classes under com/...