Build Path Issue - java

In Eclipse we have a project where we reference an external jar in the build path. When I upload my project to the repository and my colleagues check it out, the build path looks for the jar file in the same place. One of us uses a Mac so doesn't even have a C: drive and my other colleague has a different partition containing the jar, so it always breaks.
How do we fix this issue? Ideally the jar file would be included as part of the project but it seems that the svn commit doesn't include the referenced library.
Thanks

I would suggest you use a build tool (maven, ant/ivy, gradle, etc) along with a repository manager (such as nexus or archiva), depending on what you use to build your project. These store libraries in a central location(s) and then users get the libraries from there.
In eclipse, when you include your .classpath file in the checkin, you will have the issues you are describing, since the .classpath file will contain the path to the file, and then you all must have the files in the same locations. A workaround for this is to create a "lib" directory and put all of the libraries in there. Each of the users can then add all of the libraries in that directory to their path (but do not checkin the .classpath file). This is an older way of doing things before the concept of dependency managers.

Add the jar as part of the project (say in a lib folder in your project) and commit it to svn.

Start using Maven, to resolve your dependencies.
Worst case : Commit the external jar into another project called MyProjectDependencies

You can use Apache Maven to avoid incident like this and to get many others pluses.
You can find many guides on maven, for example this one.
Eclipse has integration with maven.

1.) Check in JAR in a directory inside the project.
2.) Use Maven (or something similar) to manage your dependencies.
3.) Create a User Library referencing the JAR and refer to it this way in your project. Each user will need to create the User Library in their install of Eclipse, but it sounds like you're already doing something similar by referencing the library externally anyway.

if you don't want to use a dependency management tool like Maven, a simple solution in your case would be to use an Eclipse Classpath Variable. All projects can reference the variable, but it will have a different value for each developer.
Set up a Classpath Variable with:
Right click on the Project, select Project Properties
Click Add Variable
Configure Variables
New...
Name the variable and point to a Folder
Now commit your .classpath file. The variable will be referenced in the .classpath. Each developer can configure to their particular directory, and Extend the variable to a specific jar file.

Related

How Can i add Library Jar files into the modules

I am trying to use loaded jar files of my class path into my module. I
know requires will accept only modules names.
my jar files are present inside the Spring Jar Files folder.
I tried to use #Configuration annotation inside my appConfig.java file and IDE could not recognize it.
Your help is much appreciated as I am new to the programming world.
Normally, I use Maven or Gradle to handle all the jars.
It seems you have just started with Spring.
I suggest you try Spring Boot with Maven or Gradle to manage the library and the code lifecycle (compile, build, test).
This is one tutorial for example: https://spring.io/guides/gs/spring-boot/
You can add a jar in Eclipse by right-clicking on the Project → Build Path → Configure Build Path. Under Libraries tab, click Add Jars or Add External JARs and give the Jar.
Example link
The above solution is obviously a "Quick" one. However, if you are working on a project where you need to commit files to the source control repository, I would recommend adding Jar files to a dedicated library folder within your source control repository and referencing few or all of them as mentioned above.
I'd suggest go for the second one if you are planning to build this as a proper project and put it in a source control repo.

Where to put Java libraries?

I'd like to know how I can add Java libraries to an Eclipse project on a development machine so that they can be added to an Eclipse project without causing errors when someone who has the library in a different location. For example, one developer might add an external JAR in C:\Java, but another might have the same JAR somewhere else. (Where's C:\Java on Mac OS?) I thought I might set the CLASSPATH environment variable, but I can't figure how to add an external JAR from the CLASSPATH environment variable. I'd like to do this so that it works with any workspace. Is this possible?
This is specifically for use with Anypoint Studio, but I think the same problem would exist with any Eclipse-based IDE.
In general, it's recommended to either embed JARs directly into the project, usually in a /lib folder of the project, as described here; or to use a tool like Gradle or Maven to manage dependencies, both of which have nice plugins to support their use in Eclipse.
Another alternative would be to use a Classpath Variable to refer to the JAR(s), which abstracts the physical location so that it can be set on a per-workspace basis.
I think the best way to add library to eclipse project is creating a directory - lib in your project directory. Then add the whole lib to you eclipse class path. You can follow these step to add a lib to class path -
Right click on project and select properties
Select Java Build Path
click Add Library and create User Library
Now add External Jars to this library create at step 3.
By this a .classpath file is crated in you project directory and the CLASSPATH problem will be resolved
I guess the best way to do that would be using Maven, or a similar build system that can construct your Classpath base on dependencies.
You can add the dependencies to your pom and having the jars in your local maven repository in the machine.
http://maven.apache.org/guides/introduction/introduction-to-dependency-mechanism.html
Because in any other approach you will need to maintain everything manually, and when having different OS the path will change.
Eclipse is just the IDE that will help to write code and assemble the project (JAR, WAR, ... ). You can add your external jars from wherever you want, and when you want to export your project (with eclipse) you may choose to package the required libraries into the jar.
However, I recommend always to use maven (or something like ) to avoid this kind of problems.
Part1:(import .jar file as library in Eclipse)
You make a new project to Eclipse(name:Project1)
When you open it you see JRE System Library[java version something]
1.right click on JRE System Library
2.Go->Build Path->Configure Build Path
3.You can see (Up right Corner the button[add jars or add external jars]
*Here i advise you to choose the first(add jars) but..
*First copy(or move) the (name).jar inside the project((example):Project 1)
*Now you can add it with the button(add jars).
*In this way when you finish your project the (name).jar will be
imported inside the project(If you export it as a .jar from Eclipse)
..Now you can call any method of (name).jar just(import it into the class
you want to use and call it)

Can I refer to a Java source path using a variable in Eclipse

Background
I'm using an Eclipse 4.2 (Juno) release to build a plugin for a Java application. The source code and classes for my plugin all reside within the project workspace. The application jar and its source code are, for various reasons maintained outside of the eclipse workspace and the application jar is produced by another build mechanism.
This isn't a problem as I have referenced the application jar file in my project using drag and drop and the 'Link to files' option specifying it 'Create link locations relative to: MYDEV', where MYDEV is a Linked Resource Variable I have created for each Eclipse installation. This lets me use the same eclipse project on multiple machines where the path to the application jar varies, but is always the same relative to MYDEV.
However, I cannot find a way to associate the application source code with this jar unless I use an absolute path. I only want access to the application source for debugging purposes.
Question
In Eclipse, how do I attach java source to a referenced jar in a way that allows a project to be used on multiple installations where the referenced source code has been relocated?
If the source is outside the proyect, then there's no way to access it without an absolute path.
The best solution is using a symlink inside the eclipse project directory to the actual source folder; eclipse won't notice the source is outside the project directory and everything will work fine, without having to relocate the source.
This is the only way I was able to do what you are suggesting (do not know if there are better ways).
Package a JAR file that contains the source code of the JAR file. Place it inside your project in a folder (you do not need to add it to your class path)
In the eclipse project right click on the JAR file and go to "properties" and then to "Java Source Attachment" From there select "Workspace" button and pick the jar file with the source code we added from the above step.
So the source attachment path will always be relative to the project. That way if you share the project via SVN, GIT or whatever, the source will always be available and it'll work if the user is running eclipse on Windows or Linux.
I've had a similar problem to you where absolute paths were a problem for people using different OS and not even using mapped drives via Samba helped that much.
Hope this helps.
The way I have solved this problem is to use a use defined library in eclipse. Here the steps that you can use to solver this problem.
Create a simple project in eclipse in the directory that contains the jars and the source code files.
Define a java user library add the jars to the user library and for each jar in the library specify the location of the source. If the source files are in a project that is in the workspace then the path will be relative to the workspace folder.
Export the user library as an .xml file
When another use wants to setup an eclipse workspace with the same setting as yours they will do two things.
Import the project that contains the jars and the sources into their workspace.
Import the user library into their workpsace.

Resolving Netbeans Library conflict, when using Subversion

I have a Netbeans Java Project under Subversion (svn). This is shared with another guy working on the project.
The project requires an external library that we have as a jar file. Now, when either of us makes a change and commits it, the project's library dependencies fail as we have different paths for the library ( as we are working on different machines the location of the jar file is different ).
This means that every time I update my repository, I have to resolve library dependencies.
Is there a way I can prevent this?
1st way: You can use NetBeans Library support.
Go to Tools->Libraries, and new Library with your jar. Name it the same way on both machines and include to your NB project as Library rather then direct path to jar.
2nd way: use relative path.
Agree on having jar located at ../lib/foo.jar and use this path in NB project
3rd way: use property file.
Add file named, for example, build.properties but don't commit it to svn. So both of you will have different local version of that file.
Content should be something like next:
myproject.library.foojar=C:/foopath/foo.jar
In your build.xml include this file:
<property file="../build.properties"/>
In your nbproject/project.properties find a reference to the jar -- it will look like:
file.reference.foo.jar=C:/foopath/foo.jar
change it to
file.reference.foo.jar=${myproject.library.foojar}
Also you may want to add build.properties into ignore list for svn to avoid commiting it.
I recommend you to use Maven to control library dependencies(jars). It is easy to use and NetBeans has a module to use it easily.
Maven download all the dependencies you declared into a local repertory so you don't need to worried about managing libraries, Maven do it for you.
Also with this module you can search libraries in the Maven repertory(Has a lot of java librarys) only you need to type the name and maven download it for you.
Here there are some links for how to use Maven With NetBeans:
http://platform.netbeans.org/tutorials/nbm-maven-quickstart.html
http://today.java.net/article/2009/10/14/working-maven-netbeans-671

Add Maven Classpath

My project requires some external libraries to build in in Eclipse. They live in /trunk/lib whereas my project is in /trunk/projectA. To get Eclipse to find the libraries on all machines we set a variable PROJECT_A_HOME.
Now I'm trying to get some builds going with maven and I can not figure out how to add that path (be it environmental variable or relative to $(basedir)) to the build. I really do not want to set up a repository for these dependencies, as I keep them in source control and want builds to continue to work in Eclipse.
I've seen talk about but that hasn't worked for me.
Ideas ?
You should put your static configuration files in resources/ dir. If you have your own or proprietary jars you should set a your own repository so you can download them from the repository or better yet just install them manually , here is how
http://maven.apache.org/guides/mini/guide-3rd-party-jars-local.html
Setting up a file-based repository as suggested in this previous question would allow to keep the libs in your version control system and work seamlessly at the Eclipse level (the libs would be treated like any other dependency). The only problem I can think of could be at the continuous integration level: a build of projectA would require a checkout of trunk/lib. Many CI tools would allow to implement this though. And if not, moving the libs under projectA (or another mavenized project project if you need to share them between modules) would do the trick.

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