Develop Reference

How to Make Java .jar files be automatically found in any environment

I am trying to add an external library to my Java project. The library files are in .jar format, and every time someone tries to run the project in a different environment, they have to modify the build path so that their environment can find the .jar files.
Is there any way to make it so that the .jar files are automatically found by the build path? Maybe by specifying where in the project the .jar files are located?
Edit: Here is an example -
In my linux environment, the .jar files are located in:
/home/MyUsername\SomeDirectory\workspace\java_project_name\data
In my windows environment, the .jar files are located in:
C:\MyUsername\SomeDirectory\workspace\java_project_name\data
In the example above, the project root directory is "java_project_name", and the .jar files are always in the java_project_name\data folder. Even though this is the case, different environments can't seem to detect that it is always in the same path in relation to the project's root directory.
I have looked in many places on how to do this, and some people told me it isn't possible. This doesn't sound reasonable to me, which is why I am posting this question here.
Thanks in advance for your help!

you can add a ClassPath: entry in your manifest file of the main jar, and use relative paths. As long as the jars are found relative to the main jar it will work.

This issue was one of my main motivators to start using maven.
#YoK nicely quotes here the relevant reasons to this question https://stackoverflow.com/a/3589930/1493954
Here is one the relevant quotes from Benefits of using Maven
Henning
quick project setup, no complicated build.xml files, just a POM and go
all developers in a project use the same jar dependencies due to
centralized POM.
getting a number of reports and metrics for a project
"for free"
reduce the size of source distributions, because jars can
be pulled from a central location

This is a common problem for developement environments.
I myself use the following solution in netbeans [Hope so that it works in your IDE too]:
Create an Ant variable [for e.g. JAR_LOCATION].
Each and every JAR that you refer, must have it's location relative to JAR_LOCATION.
Now, in every development environment that you're gonna use, you can set up the same ANT variable and it'll automatically pick up the JAR.
You can see the example in the given snapshot of netbeans..

Netbeans: need to include 3'rd party directory in classpath

We have an application developed in NetBeans, based on the NetBeans platform. There's a 3'rd party program that we have a runtime dependency on, more specifically a jar in the other progams lib folder.
How should we include the other progam's jar in our classpath?
The recommendation from the other progam's manufacturer is to set environment variable CLASSPATH to include
C:\Progam Files\Other Program\lib\theJAR.jar
And if that's not possible, we should copy theJAR.jar to JRE-HOME\lib\ext
We must not copy theJAR.jar anywhere else, that might cause it to stop working...
Now NetBeans takes no notice of what's on environment variable CLASSPATH. Their recommended way seems to be to make a wrapper, but that would lead to copying the jar, unless there's some way to make a wrapper module that points to CLASSPATH?
At the moment we are copying the jar into JRE-HOME\lib\ext. But then there's unnecessary hassle when we install some java update.
Do you have any solution to this problem? It seems like something that might be simple, but I haven't found the right place to look yet...
Edit: The application is ant-based.

From the documentation for the Module System API's overview of the runtime infrastructure (bottom of the page under the section "Common Problems and Solutions"):
Q: Can my module add a library JAR to the classpath from outside the
IDE [read: platform] installation?...
A: Not easily. You have a few options:
Add an entry to ide.cfg [your app's .config file]. For example:
-cp:a c:\eak\lib\eak.jar This startup file provides the ability to add classpath entries to the IDE's Java invocation.
...
It goes on to list two more options. The second option is the same solution you've come up with. The third is to "partition your module and use a new classloader" which I can't recommend either way since I have no experience doing this (but it's worth a read).
Assuming that this first option is what you are looking for, you will need to add a custom .conf file to your project and point to it in your project.properties file, like so: app.conf=nbproject/my.conf. This will add your custom .conf file to your app's install directory instead of the default config file that is normally added. Of course, you'll need to add the -cp:a c:\eak\lib\eak.jar entry to this custom config file in order to load the .jar.
During development you'll need to add the following entry to the project.properties file: run.args.extra=-cp:a c:\eak\lib\eak.jar. This will pass the command line option to your debug instance.

You can add that .jar file by following the steps below:
In the left side panel named "Projects" open your project and right click on the "Libraries", then select "Add JAR/Folder...".
Then select your .jar file from the location where you have stored it in the next dialog box that opens and then press "Open".
Vola Finished!!! (with the same process you can add other libraries also like JavaCV, JMF,etc)
And Now You Can Use That .Jar File From Your Project Library.
Hope It Helps.

How do I add logging.properties to the classpath of an Eclipse project?

I'm using Eclipse 3.7.1 and my code isn't seeing my logging.properties file. (I thought it would see it automatically because it is in the standard place within the JRE but that is apparently wrong). I've been told I need to add this file to the root of the classpath but I'm not sure how to do that.
Eclipse gives me ways to add jars, libraries, variables and other things to the classpath but I don't know how to add a properties file. Can anyone clue me in? You'd think it would be easier to add a simple text file than to add a jar but I don't see any options for text files or property files so I'm not sure how to proceed.

Right click on your project->Run/Debug Settings->Edit the launch configuration you are using->Switch to Classpath tab->Right Click User Entries->Add the Folder (or External Folder) containing your properties file->Click Apply . I am assuming you are referencing to a console application here.
If you put the properties file in the root level of the project (that's where the project folder is created), then it should be automatically included in the class path.
You should know that a CLASSPATH never includes specific files. It generally includes folders, jars, etc.

Add a properties file to IntelliJ's classpath

I'm running a simple Java program from the IntelliJ IDE using the Run->Run menu. It works fine. Now I want to add log4j logging.
I added a resources folder under my project root.
I added a log4j.properties file in that folder.
I changed the code to log something.
What is the right way to tell IntelliJ to include the resources folder in the classpath so the properties file is seen?
With IntelliJ 8 I could guess like a drunk monkey and eventually get it to work. I have 9 now and I am wholly unsuccessful. I've been trying for an hour. How about an "Add to classpath" option somewhere? /fume /vent /rant

Try this:
Go to Project Structure.
Select your module.
Find the folder in the tree on the right and select it.
Click the Sources button above that tree (with the blue folder) to make that folder a sources folder.

Actually, you have at least 2 ways to do it, the first way is described by ColinD, you just configure the "resources" folder as Sources folder in IDEA. If the Resource Patterns contains the extension of your resource, then it will be copied to the output directory when you Make the project and output directory is automatically a classpath of your application.
Another common way is to add the "resources" folder to the classpath directly. Go to Project Structure | Modules | Your Module | Dependencies, click Add, Single-Entry Module Library, specify the path to the "resources" folder.
Yet another solution would be to put the log4j.properties file directly under the Source root of your project (in the default package directory). It's the same as the first way except you don't need to add another Source root in the Module Paths settings, the file will be copied to the output directory on Make.
If you want to test with different log4j configurations, it may be easier to specify a custom configuration file directly in the Run/Debug configuration, VM parameters filed like:
-Dlog4j.configuration=file:/c:/log4j.properties.

I have the same problem and it annoys me tremendously!!
I have always thought I was surposed to do as answer 2. That used to work in Intellij 9 (now using 10).
However I figured out that by adding these line to my maven pom file helps:
<build>
...
<resources>
<resource>
<directory>src/main/resources</directory>
</resource>
</resources>
...
</build>

I spent quite a lot of time figuring out how to do this in Intellij 13x. I apparently never added the properties files to the artifacts that required them, which is a separate step in Intellij. The setup below also works when you have a properties file that is shared by multiple modules.
Go to your project setup (CTRL + ALT + SHIFT + S)
In the list, select the module that you want to add one or more properties files to.
On the right, select the Dependencies tab.
Click the green plus and select "Jars or directories".
Now select the folder that contains the property file(s). (I haven't tried including an individual file)
Intellij will now ask you what the "category" of the selected file is. Choose "classes" (even though they are not).
Now you must add the properties files to the artifact. Intellij will give you the shortcut shown below. It will show errors in the red part at the bottom and a 'red lightbulb' that when clicked shows you an option to add the files to the artifact. You can also go to the 'artifacts' section and add the files to the artifacts manually.

Faced a similar challenge adding files with .ini extensions to the classpath. Found this answer, which is to add it to Preferences -> Compiler -> Resource Patterns -> [...] ;*.ini

If you ever end up with the same problem with Scala and SBT:
Go to Project Structure. The shortcut is (CTRL + ALT + SHIFT + S)
On the far left list, choose Project Settings > Modules
On the module list right of that, select the module of your project name (without the build) and choose the sources tab
In middle, expand the folder that the root of your project for me that's /home/<username>/IdeaProjects/<projectName>
Look at the Content Root section on the right side, the red paths are directories that you haven't made. You'll want to put the properties file in a Resources directory. So I created src/main/resources and put log4j.properties in it. I believe you can also modify the Content Root to put it wherever you want (I didn't do this).
I ran my code with a SBT configuration and it found my log4j.properties file.

For those of you who migrate from Eclipse to IntelliJ or the other way around here is a tip when working with property files or other resource files.
Its maddening (cost my a whole evening to find out) but both IDE's work quite different when it comes to looking for resource/propertty files when you want to run locally from your IDE or during debugging. (Packaging to a .jar is also quite different, but thats documented better.)
Suppose you have a relative path referral like this in your code:
new FileInputStream("xxxx.properties");
(which is convenient if you work with env specific .properties files which you don't want to package along with your JAR)
INTELLIJ
(I use 13.1 , but could be valid for more versions)
The file xxxx.properties needs to be at the PARENT dir of the project ROOT in order to be picked up at runtime like this in IntelliJ. (The project ROOT is where the /src folder resides in)
ECLIPSE
Eclipse is just happy when the xxxx.properties file is at the project ROOT itself.
So IntelliJ expects .properties file to be 1 level higher then Eclipse when it is referenced like this !!
This also affects the way you have to execute your code when you have this same line of code ( new FileInputStream("xxxx.properties"); ) in your exported .jar.
When you want to be agile and don't want to package the .properties file with your jar you'll have to execute the jar like below in order to reference the .properties file correctly from the command line:
INTELLIJ EXPORTED JAR
java -cp "/path/to_properties_file/:/path/to_jar/some.jar" com.bla.blabla.ClassContainingMainMethod
ECLIPSE EXPORTED JAR
java -jar some.jar
where the Eclipse exported executable jar will just expect the referenced .properties file to be on the same location as where the .jar file is

Right-click on your directory and from Mark directory as select Resources root as below:

Perhaps this is a bit off-topic, seeing as the question has already been answered, but I have experienced a similar problem. In my case only some of the unit test resources were copied to the output folder upon compilation. My persistence.xml in the META-INF folder got copied but nothing else.
In the end I "solved" the problem by renaming the problematic files, rebuiling the project and then changing the file names back to the original ones. Do not ask me why this worked but it did. My best guess is that, somehow, my IntelliJ project had gotten a bit out of sync with the file system and the renaming operation triggered some kind of internal "resource rescan".

This is one of the dumb mistakes I've done. I spent a lot of time trying to debug this problem and tried all the responses posted above, but in the end, it was one of my many dumb mistakes.
I was using org.apache.logging.log4j.Logger (:fml:) whereas I should have used org.apache.log4j.Logger. Using this correct logger saved my evening.

I had a similar problem with a log4j.xml file for a unit test, did all of the above. But figured out it was because I was only re-running a failed test....if I re-run the entire test class the correct file is picked up. This is under Intelli-j 9.0.4

How do I include .class files in my project in Eclipse? (Java)

Hey all. I am working on a project for school where we are given the .class file but not the source to include in our code. I am using Eclipse, and I want to include the file in my project so I can instantiate objects from it and use it. The file is TokenizerImpl.class, and I want to use it like this: TokenizerImpl tokenizer = new TokenizerImpl(foo);
I put the file in my project folder, and Eclipse says that "TokenizeImpl cannot be resolved as a type", which I assume means it cannot find the class or source. I tried putting it in the "bin" folder of the project and got the same error. Google search and SO search didn't seem to answer this, so I will give it a shot. How do I do this, oh wise ones?
Edit: Oh dear, I found the problem was something else entirely. These solutions worked fine, but I just forgot to create the Tokenizer interface that TokenizerImpl implements. Doh. Thanks for all your help though, I did learn a lot about eclipse.

You can add a directory containing the class files to the Eclipse project, only if it is inside one of your Eclipse projects, either in a generated directory or in one you have created.
This can be done by adding the class folder to the Java build path of the application. You can set this in the Project properties, by visiting Java Build Path -> Libraries -> Add Class Folder. Keep in mind, that you will have to specify the root folder containing the class files in their packages.
Therefore, if you wish to have the compiler access com.stackoverflow.Example.class present in the classes directory under project A (but not in the build path of project A), then you should add 'classes' as a class folder, and not classes/com/stackoverflow as a class folder.

Project -> Properties -> Java Build Path -> Libraries -> Add External Class Folder
The folder must contain a package hierarchy, i.e. if your class is really foo.bar.TokenizerImpl it must be in the subdirectory foo/bar.

You could also JAR the class files that you want to add and add the JAR file to the build dependencies. To me this is the cleanest solution. Internally the JAR file has to have the correct directory structure, of course.
Right click into your project and select Java Build Path to add new dependencies.
Copying it into the bin folder won't work very well because it is meant to hold the result of compiled sources. As soon as you clean anything the file will be gone.

or put everything into a jar file and add this as an external jar.

Other people have now given better answers. This "answer" was mainly to get information from the OP because the original question didn't really tell us, fully, what had been tried. There are now two answers that truly answer the question in a long-term way.
My original answer is left below for context.
Did you copy it to the bin folder within Eclipse or outside Eclipse? If you did this outside Eclipse then you have to right click on the "bin" folder and select "refresh" for Eclipse to see the new file.
A *.class file in the appropriate folder (depending on its package) under the bin directory should do it.

zip the class folder.
Highlight project name, click "Project" in the top toolbar, click "Properties", click "Libraries" tab, click "Add External jars", add the zipped file