I've seen different packages in source code such as com.website.package These packages are used across multiple applications, and I've been trying to accomplish something similar.
The only way I know of to achieve using the same packages in different projects is to copy each source file into the new project which would create the new packages. this probably isn't the preferred method, as it could possibly drag thousands of files into the project (see Java's library).
How would this be achieved?
TL;DR: How can I use a custom written package in multiple projects without copying many files? (aka Java's libraries).
Take the class files and create a jar. Put the jar on the classpath of all the applications that need those classes.
How do you do that?
Inside an IDE, you can create multiple projects and put the shared java code in one project. Make the other projects depend on that project and you can share things within the IDE. That means you run inside the IDE and it will use the shared code.
For example, in Eclipse, you choose the project that will use the shared code/project. Right click on it in the package view or navigator view and choose "properties". Select the option to set the build path and there is a tab for selecting projects that this project depends on. Select the shared project and then it's code is callable from that project.
In this case, any change you make to the shared project will be immediately available, inside the IDE, to those projects that depend on it. Run them right then and the change will be in effect.
For running outside the IDE ...
If you are using Eclipse (or some other IDE) it will have an option for creating a jar. In Eclipse you create a java project and move the classes you want to be in the library/jar into this project. Then, once you have all the right classes, including those that others depend on, you will do some sort of build to create the jar.
Eclipse has an 'export' option on the 'file' menu. Use that and select to export as a "java" > "jar" and then select the project you just made.
You can also create a Maven project of type "jar" into which you put all those classes (as java files) and then building that project with Maven will create the jar. The "install" goal for Maven will deploy it to your local repository.
Any time your shared code is shared by way of a jar, you will have to rebuild the jar and copy it into the location(s) from which it is shared by other projects before changes inside the jar take effect.
Maybe export the package to some place on the drive and create linked folders to it in the projects?
Related
I have a Java project that depends on a 3-rd party component. This component is available both as a jar and as a Maven/Ant project. One option for me is to simply add the jar as a library. However, I prefer to add the source code into my project since I may need to slightly modify their source code to better suit my needs.
What's the right way to do it in Eclipse?
My main project has a simple structure: src/ and lib/. The external component also has a standard structure: src/, test/, build/, target/, pom.xml, build.xml. So do I need to copy piece by piece (like contents of one src/ into the other src/), in which case what goes where? Or do I somehow copy it all at once? Or smth else?
The best way would be if you use maven on your projet for dependency management. This way, if you have the other projects open in eclipse, your project will resolve them as local projects, but if you don't, maven will try to fetch the jars from the configured nexus repository.
This way, you avoid having to manually configure your Eclipse projects. Maven will be able to configure your project anywhere you want to build it, not having to manually configure dependency resolution.
Import both the projects into eclipse. Add the reference of 3pp jar project to your project as a reference by clicking on Add on build path option. While delivering it as output there will be a dependency to the 3pp jar project. So either deliver it as separate jar and add it to classpath while executing your project else you have to copy the entire source files into your project and deliver it test complete jar.
Making a jar will be handled by eclipse itself.
Recently I was forced into using Eclipse because of TFS plugins:
I have a few projects that I'm converting to Eclipse projects from Netbeans. Some of these projects reference each other. After starting to convert these projects I quickly found that Eclipse doesn't want to jar projects post-build. So I used an build.xml and created a new 'builder' for each project (whose bright idea was it to not allow me to reuse builders across multiple projects?). After I got all that working I was sitting back thinking about how I would go about building for deployments, and it occured to me that eclipse is not including any of the referenced assemblies in the build output directory. This sucks, because manually creating lib folders and copying over all of the jar files which are required will be error prone, and time consuming. So heres the question. Is there any reasonable way to set up a builder, or property on an eclipse project such that when I build it, it will create a 'dist' directory, containing both the jar'ed project classes, and a lib folder with all of the referenced jars attached to the project?
Is there any reasonable way to set up a builder, or property on an eclipse project such that when I build it, it will create a 'dist' directory, containing both the jar'ed project classes, and a lib folder with all of the referenced jars attached to the project?
Yes, right-click on the Project and select Export. Type "jar" into the search box and select Runnable JAR file. In the export dialog, select the "Copy required libraries..." option. There should also be an option there to save this export as an Ant script.
I dont know how to resolve a list of dependencies using ANT
Next, you should consider using Ivy. This will add dependency management to your build script. There's probably some learning curve here, but these tutorials should help.
i have a maven desktop project, and it consists of several packages, and i was wondering if it's possible to extract one of the packages as a separate jar, so i can reuse it, instead of making a new project that contains only this package ?
You could use the includes parameter in the maven jar plugin to achieve this. In fact the usage page has an example on how to do this.
You could do this within a profile so that you can continue to build the normal project with all classes.
I have a Web Project with two source folders in Eclipse. Folder A, depends on Folder B being compiled. Is there a way to create this dependency in Eclipse, without having to create separate projects for each folder? I know projects can be set up to depend on one another, but I am not looking to do that.
The eclipse compiler automatically manages dependencies at the source level within all source folders of a project, you don't have to do anything special.
Edit: You answer "you would not be able to have Folder B reference classes in Folder A" to a comment - that's kinda the opposite of a dependency. And no, I'm pretty sure you cannot enforce that within a single eclipse project.
You can create a ant task to do that for you
You can have two programs in the same Eclipse project, with two separate main methods. You can then make two separate Run Configurations.
Before running you can then build the project. Building the project will automatically build both programs in the project, so you wont have to remember to manually build your second program.
I download the Apache POI from apache.org but don't know how use it with one of my existing project in Eclipse.
There are several ways, some good, some bad...
Add external Jar - as jjnguy says will work. However, not a good option...
The problem is that if you share your project with someone else and they have the jar in a different spot, they'll get build path errors
Add variable - similar to add external jar, but much more flexible. You can define a classpath variable (under Java prefs) that represents the dir containing jar. In your project, when you add variable, you choose the var you defined and press "extend" to specify the actual jar. As long as you and other developers of your project define the variable, you can have the jar in different spots if you like
Add the jar to your project - create a dir in your project (optional, maybe call it lib) and import the jar into it using File->Import or if your OS supports, drag it as an icon into the folder (On windows I open an explorer window and drag it from there into the folder in eclipse). Then, right-click the jar and select Build-Path->Add to build path.
Add the jar in a separate project and reference it. Add the jar as mentioned in the last bullet to a separate project for that jar. Choose Build-Path->Configure Build path from the project. Go to the "order and export" tab and make sure the jar is checked. Now you can configure your project to reference the new project. This makes things more modular.
Create a user library - under Java prefs you can define a "user library" that contains the jar. This is somewhat similar to a classpath variable, but can reference multiple jars and you only have to add it once to the project.
Create a classpath container plugin. This is more complex, but is a nice option if you are providing a set of plugins for folks. A classpath container can be added like a library to a project and it can manage the jars, even searching for them if you want it to.
You can find the option to add external jars to a project in: Project > Properties > Java Build Path > Libraries tab.
Click on 'Add External Jar' and find where you have the POI library.