Develop Reference

Zip Referenced Libraries into Eclipse project

I have no experience with package structure. I added two external libraries (from Joda) to my eclipse project. The code makes use of the libraries with no problems. However, when I export the Archived File and open it on another computer, the libraries are no where to be found. Much sadness.The error looks like a little red exclamation point next to my project in the package explorer. Checkboxes next to the libraries have been checked/applied.

Right click on your project
Navigate to build paths -> configure build path
In order and export tab check whether the library is in the list or not
If it is not selected, tick the Checkbox and click apply

Someone told me that I need to export it as a executable jar.

Attach the Source in Eclipse of a jar

I added a Student.jar into my Build Path in my eclipse like this-
Right click on the project->BuildPath->Configure Build
Path->Libraries->Add External Jars
There is one class named StudentTest in Student.jar file. When I was debugging my code in eclipse, I stepped into that StudentTest class in the Student.jar.
And after that eclipse shows me like this-
The JAR file S:\some_location\Student.jar has no source attachment.
You can attach the source by clicking Attach Source below
Now I am not sure how should I attach the source in my eclipse. And from where? Can anyone provide me step by step what I need to do.
Update:-
I tried unzipping the Student.jar and I got Student folder. And after that I tried pointing the source to Student folder But still I am not able to see the class properly so that I can debug it properly, it shows the same above behavior.

Use Java Source Attacher !
It does what eclipse should do - a right click context menu that says "Attach Java Source.
It automatically downloads the source for you and attaches it. I've only hit a couple libraries it doesn't know about and when that happens it lets you contribute the url back to the community so no one else will have a problem with that library.

Eclipse is showing no source found because there is no source available . Your jar only has the compiled classes.
You need to import the project from jar and add the Project as dependency .
Other option is to go to the
Go to Properties (for the Project) -> Java Build Path -> Libraries , select your jar file and click on the source , there will be option to attach the source and Javadocs.

A .jar file usually only contains the .class files, not the .java files they were compiled from. That's why eclipse is telling you it doesn't know the source code of that class.
"Attaching" the source to a JAR means telling eclipse where the source code can be found. Of course, if you don't know yourself, that feature is of little help. Of course, you could try googling for the source code (or check wherever you got the JAR file from).
That said, you don't necessarily need the source to debug.

This worked for me for Eclipse-Luna:
Right Click on the *.jar in the Referenced Libraries folder under your project, then click on Properties
Use the Java Source Attachment page to point to the Workspace location or the External location to the source code of that jar.

Go back in to where you added the jar. I believe its the libraries tab, I don't have Eclipse open but that sounds right. to the left of the jar file you added there should be an arrow pointing right, click that and 3 or 4 options expand, one of them being the source file of the library. Click on that and click edit(I think you can also double click it) then locate the file or folder on your hard disk, you probably have to click apply or okay and you're good to go, same with javadoc and i think the last one is native libraries. I don't pay much attention when I'm in there anymore if you couldn't tell. That's what you were asking, right?

I Know it is pretty late but it will be helpful for the other user, as we can do Job using three ways... as below 1)1. Atttach your source code using i.e, Right click on the project then properties --> Java build path--> attach your source in the source tab or you can remove jar file and attach the source in the libraries tab
2. Using eclipse source Analyzer In the eclipse market you can download the plugin java source analyzer which is used to attach the open source jar file's source code. we can achieve it after installing the plugin, by right click on the open source jar and select the attach source option.
3. Using Jadclipse in eclipse you can do it last not the least, you can achieve the decompile your code using this plugin. it is similar way you can download the plugin from the eclipse market place and install in your eclipse.
in jadclipse view you can see your .class file to decomplile source format note here you cannot see the comment and hidden things I think in your scenario you can use the option one and option three, I prefer option three only if i want to the source code not for the debug the code. else i ll code the option 1, as i have the source already available with.

Simply import the package of the required source class in your code from jar.
You can find jar's sub packages in
Eclipse -- YourProject --> Referenced libraries --> yourJars --> Packages --> Clases
Like-- I was troubling with the mysql connector jar issue
"the source attachment does not contain the source"
by giving the path of source folder it display this statement
The source attachment does not contain the source for the file StatementImpl.class
Then I just import the package of mysql connector jar which contain the required class:
import com.mysql.jdbc.*;
Then program is working fine.

I faced the same issue and solved using the below steps. Go to Windows->preferences->Editors->File Associations
Here click on Add
then type .class
click on OK
again click on Add
then type .classwithoughtsource
click on OK
Now you will be able to see JadClipse option under Java section in Windows->Preferences
Please provide the path of jad.exe file as shown below.
Path for Decompiler-C:\Users\ahr\Documents\eclipse-jee-galileo-SR2-win32\jad.exe
Directory for temporary Files-C:\Users\ahr.net.sf.jadclipse
click on Apply
Now you should be able to see the classfiles in proper format.

It is quite possible, just go to the jar in the Build Path and choose to attach a source just like follow.

Download JDEclipse from http://java-decompiler.github.io/
Follow the installation steps
If you still didn't find the source, right click on the jar file and select "Attach Library Source" option from the project folder, as you can see below.

I am using project is not Spring or spring boot based application.
I have multiple subprojects and they are nested one within another.
The answers shown here supports on first level of subproject.
If I added another sub project for source code attachement, it is not allowing me saying folder already exists error.
Looks like eclipse is out dated IDE. I am using the latest version of Eclipse version 2015-2019.
It is killing all my time.
My intension is run the application in debug mode navigate through the sub projects which are added as external dependencies (non modifiable).

I have faced same problem and resolved it by using following scenario.
First we have to determine which jar file's source code we want along with version number. For Example "Spring Core" » "4.0.6.RELEASE"
open https://mvnrepository.com/ and search file with name "Spring Core" » "4.0.6.RELEASE".
Now Maven repository will show the the details of that jar file.
In that details there is one option "View All" just click on that.
Then we will navigate to URL "https://repo1.maven.org/maven2/org/springframework/spring-core/4.0.6.RELEASE/".
there so many options so select and download "spring-core-4.0.6.RELEASE-sources.jar" in our our system and attach same jar file as a source attachment in eclipse.

Try removing the breakpoints. :)

Trouble understanding the usage of external libraries in a java project/IntelliJ

Now that I've learned a bit more, I can ask a more direct question.
Scenario:
I have a Java project in IntelliJ Idea, with the end goal of making a standalone .jar capable of running on Windows or Linux, either run from the command line with java -jar jarname.jar or simply by being double-clicked like any normal, simple jar.
I've written a handful of classes, located in my src/package/name directory. However, one of my classes requires the use of an external class, i.e. a class not located in my source directory or is not part of Java's default set of .jar's in the JDK.
How do I go about configuring IntelliJ to build the .jar artifact AND include the necessary resources inside of it, with everything needed put in the proper place, so that my class can use the resource by an ordinary import statement? An answer given in example form would be awesome; I've almost figured it out, but there must be just one thing I'm not doing correctly.
Thanks for your time,
Yankee
Sources:
http://tukaani.org/xz/java.html
Viewing the directory structure of that source gives a better idea:
http://git.tukaani.org/?p=xz-java.git;a=tree

One does not simply package Mordor into their jar.
After much experimentation, I found a solution that, while maybe not the right way to do it, definitely works. The key is to:
Define your external library (a .jar in my case) as a module dependency.
Add your external resources as (what IntelliJ calls) an "Extracted Directory."
For the first item, go to File -> Project Structure. Click "Modules" in the Project Settings list on the left. In the list just to the right, you will see a list of modules (whatever they are) which belong to your project. Leave that alone, but make sure that it is highlighted/selected as the current module. What you want is the settings for that module, which will show in the window on the right. Go to the "Dependencies" tab. On the rightmost part of the screen will be a little green plus sign. Click that, choose "Jars or directories" and navigate to your relevant resource you want to bring along with your finished jar.
Note: don't be fooled by the check box that says "Export." Its only purpose is to cause endless pain and suffering as you wonder why the dependency isn't exported along with your jar. Always remember, the export box is trying to get you to click on it. It wants to be ticked :3
Next, add that resource as an extracted directory by going to File -> Project Structure. Then "Artifacts" in the Project Settings list on the left. Click the green plus sign at the top to make a new "Jar" artifact "From modules with dependencies." In the right hand window, under the "Output Layout" tab, click the little green plus sign and choose "Extracted Directory." Once again, browse to your precious jar.
You should now be able to successfully build a jar artifact that contains all the resources it needs to run as you designed it.

Here is a reference section on configuring external libraries as module dependencies - link. Regarding artifacts construction - it's possible to precisely specify its content (including dependency libraries content) - link.

Read How classes are found...
It is OK (expected that you) to ship your program in your own jar, and dependent 'libraries' as separate jars
You are expected to provide a way to run your program with the correct -classpath argument to the java command so that java can find both your jar, and the dependent jars... there are multiple ways to do that... see the link above.
Rolf

How to Build "Thinking in Java" Example Files to Run in Eclipse IDE?

I wanted to learn Java, as recommended by most of the people I downloaded "Thinking in Java" eBook and Source Code Example Lesson files from mindviewinc.com it's download location is this http://www.mindviewinc.com/TIJ4/CodeInstructions.html
These files don't work with Eclipse IDE for some reasons. So we have to build the files using the Build.xml file included in it's source code (Honestly, I do not have any idea what does "build" means here)
I tried building myself but of no use.. It did started building but after reaching some folder it stopped and gave error to install jboss-osgi-installer-1.0.0.jar .. After downloading it, I had no idea what to do with it, so I double clicked it and it asked me the location to install and I installed it in the default location, which was C:\Users\Username/jboss-osgi-1.0.0 and when I tried C:\Program Files\Java** the installation gave error that "this directory cannot be written, please choose another directory!" but anyway I installed it in the default location and it installed..
and again when I tried to build it, it gave me the same error and asked to Install Jboss....... I'm stuck.. This is happening again and again, wasted many days and didn't even crossed 100 pages of it's pdf because of this reason. It's a good eBook though.
I'm stuck in this from months... Please some one build it and make it like a project which could be easily and send me the project file, it would be really appreciated as I can not the solution to this anywhere on search engines..

Ok here's what I did to succesfully import the sources found in the "accesss" folder of you code samples:
Download the javassist jar as per Bruce's instructions, from here:
http://repo2.maven.org/maven2/javassist/javassist/3.9.0.GA/javassist-3.9.0.GA.jar
You must create an Eclipse project for the sources that are used as dependencies for most of the examples, that's the sources in the "net" folder:
in eclipse make new java project.
select the "net" directory, copy it, then in eclipse select the "src" entry in the project you just made, right click on it and select paste.
after eclipse finishes and auto-builds, it will complain about the missing javaassist jar. Right click on the project ->properties->java build path (on the left)->libraries (on the top)-> add external jars... (on the right), browse and select the javassist jar from where you down load it.
now the "net" project should be ok in eclipse
Now let's create the project for the sources in the "access" folder:
create a new java project in eclipse
Now, because Bruce structured his classes like crap, we'll have to make the proper structure in eclipse for them. This means:
a.create a new package called "access"
go to where your the access folder is on your drive, open it, select ONLY the folders (cookie2, desser, mypackage), copy them, then return to eclipse, right click on the "access" package u just made and click paste
now go back to the access dir on your drive, select ONLY the .java files (all of them, not the dirs), copy them, the back to eclipse, click on the src entry in the access project and click paste.
The access project in elcipse will still complain about missing classes form the "net" resouce. Right click on the project in eclipse->properties->java build path->projects (on the top)-> add(on the right)-> check the net project you created earlier-> click ok twice.
Now it should be ok
I hope you got the idea on how dependencies work in eclipse with this example.
For the other parts of you code samples, create separate java projects, add the classes to the proper package (create the packages if Bruce forgot to), and if you are missing external jars, go to http://search.maven.org search and download the jars. Good luck

"This code is designed to work outside of IDEs. Because packages are not introduced until later chapters, and some of the fancier IDEs like Eclipse require all code to be in packages, if you want to use the code inside those IDEs you will have to make some adjustments" - yep, bruce eckel would say that, cause that's the kind of guy he is. He also said there's ONLY checked exceptions in java, and asked for unchecked exeptions to be added as a bonus.
Now, if your sample code has no package, aka it's in the default package, aka when you look in the .java file, right at the top there's no line saying "package what.ever.bla" then all you have to do is:
-in Eclipse create a new Java se project
- open a windows explorer, go to your .java files, select them and copy them
- then in eclipse, right click the src folder in your project and chose "paste"
The files should be added to a "default" package in your eclipse project, without any error

Here is the simplest steps that I find to create a clean Eclipse project for the TIJ4 source code:
Download the source code zip from: http://www.mindviewinc.com/TIJ4/CodeInstructions.html, and unzip it to a folder, say 'TIJ4-code';
Download the additional libraries as in the previous URL, copy tools.jar from your current JDK's lib directory, and put them into TIJ4-code/lib;
Go into the 'TIJ4-code' folder, and run 'python Eclipse.py' (you need python installed on your system). This script adds the missing "package xxx" line to those source java files which don't yet have them, so as to make Eclipse happy. It also generates the Eclipse project files, which doesn't work well for some reason (beyond my limited knowledge on Eclipse), but they aren't needed here;
Open Eclipse and create a new empty java project, say with name 'TIJ4', choose JRE version 1.5, and "create separate folders for sources and class files";
Copy TIJ4-code/lib directory to your new Eclipse project folder;
Right click on the new project and select "Build Path" >> "Configure Build Path", then go to tab "Libraries", "add jars", then select all the jars under your project's lib folder;
Go to "File >> import", choose "General >> File System", select the unzipped folder 'TIJ4-code' as your "From directory". Check the root 'TIJ4-code' in the left panel of the import window, Click on "filter types" and select the .java, so that unnecessary files of other extensions, like *.class, *.py, *.xml, etc can be ignored during the import;
The zipped folder is no longer needed after the new Eclipse project is built. I hope you find this instruction helpful, and have fun learning TIJ4.

If you want to use this code in IDE rather than Eclipse and so on, for example in Intelij Idea or any other, the best way is to compile necessary classes from the TIJ4 with Ant, but it is not easy for the beginners, although it will be a good practice for you. You should make some changes in build.xml files which exists in every directory of TIJ4. Why?
to change version of Java(now we all use Java version higher than 1.5)
to include javaassist.jar library in the "classpath"
to put all compiled files in 'bin' directory(by default without adjustments TIJ4 build.xml puts .class files in the same directory with .java files. That is not a good deal.
For example you need to import and use within IDE(I use Intelij Idea) the class named net.mindview.util.Print ( see Chapter 3):
download TIJ4 and unzip in any directory you want(for example it would be c:\eckel)
download and install AntApache (you can find detailed instructions how to do it in Google) The result is - type in your console ant -version and you should see the answer. So Ant is working.
download javaassist.jar from http://jboss-javassist.github.io/javassist/ . Unzip to any directory, take out javassist.jar and past it to c:\eckel\net
4.There is build.xml file in c:\eckel\net. Now you should make adjustments. Open it with NotePad++ or other editor.
If you don't have Java 1.5 installed on your PC, so change all 'vesion1.5' to 'vesrion1.8' or other version that you have installed.
after tag description put property name = "classpath" value="./;./javassist.jar"/>
<property name = "src_util" value="./mindview/util"/>
<property name = "src_simple" value="./mindview/simple"/>
<property name = "src_atunit" value="./mindview/atunit"/>
<property name = "destdir" value="bin"/>
Then we make targets that will complile util simple or atunit automatically
Change tag available <available
classname="javassist.bytecode.ClassFile"
classpath="${classpath}"
property="javassist"
/>
Now classpath of available = property named 'classpath'. Classpath is the path where java compiler looks for .class files because some of your .java files want them by having import statement. There won't be error message "You must install the Javassist library " any more
Create targets for compiling util simple and so on See the following link with code
Code with targets
You can modify exists targets not to write all the code.
at the top of build.xml file change default="simple"
open cmd, then cd c:\eckel\net , then ant -simple or just ant (simple will run as default)
Please write if you will have some problems. Possibly i forgot mention about something.
Go to Intellij Idea, press Ctrl+Alt+Shift+S
Press +,
Library or directories
choose your c:\eckel\net\bin
5.now you can use import statement for all classes that exist in net.mindview
6.you can make the same with other dirs.

If you wish to you skip the entire Ant build process, I have converted the project to a Maven project (over JDK8), which you can simply import into your Eclipse workspace.
https://github.com/gauravojha/tij4-maven

Thanks to #Sergey Oliv's example. In addition, I needed to provide uncompiled javaassist package with all java files in the 'net' folder too. The .jar wouldn't work by itself.
I must say, this was a lot of work to get going.

After checking out Subversion code into Eclipse, how do I get it to build?

This problem has been frustrating me for some time...
A lot of sites like Sourceforge use SVN or Subversion to manage their code. I have little problem compiling SVN code in C++, but when it comes to Java, my IDE gives me a headache.
I've installed Subclipse for SVN support for Eclipse, and it works. I can check out any code into my Workspace. Now Subclipse will put the whole thing into a special project of some sort that can't be compiled. So I search Google for something and I come up with modifying the eclipse XML file to specify the 'nature' to be a Java project.
Okay, now it's a Java project. Say I have a folder structure like:
\src
\data
\graphics
I get 800 compiler errors complaining the package name is org.company.SomePackage instead of src.org.company.SomePackage.
Then what I do is create packages called src, data, graphics, etc, instead of just folders. I cut and paste everything in the folders into the packages and finally I can compile it.
What is a better way to do this?
EDIT: I can only check out anything SVN as a SVN project, and there's no way within Eclipse to change that to a Java project. How can I check out the SVN as a java project in the first place?

I get 800 compiler errors complaining
the package name is
org.company.SomePackage instead of
src.org.company.SomePackage.
Right click on Project -> Properties -> Java Build Path -> Source Tab -> Add "src" as a source folder and remove any others.

it thinks your source is stored in root folder. you need to specify to the project that /src is the source folder.

In general when we have an Eclipse project, which contains Java code – but we didn’t set it up as a Java project when we created or checked out this project, we are struck. And Eclipse doesn’t allow to change the project type inside the Gui. So we need to add the java nature as below.
1. Close your project.
2. Open your project file (which is located in your root directory of the appropriate project) called .project with your default editor. Search for
< natures>
< /natures>
and change it to as below
< natures>
<nature>org.eclipse.jdt.core.javanature</nature>
< /natures>
Save the changed file.
3. Open the project again – now it should become a java project.
Then do the following as explained by Kevin
On the Project Explorer Window ->Right click on the specific Project -> Properties -> Java Build Path -> Source Tab -> Add "src" as a source folder and remove any others.
For me when I went into “Source Tab” – the “src” folder was already added, but it was not giving me the desired result (ie I was still not seeing the .java files in the project explorer window). So I removed the “src” filed that was already added in the Source Tab and then added them again. And then all worked fine.

You have to configure proper source paths. Some open source projects make this automatic by checking their .project and .classpath files in with the rest of their files. For others, you'll have exactly the problem you are having. You need to set the classpath so the Java compiler knows where to find the source. You right click on the project and select properties and configure an arbitrary classpath, but the answer given by Kevin is easier for a beginner.