Develop Reference

Java decompiler plugin not working

I have the JD-eclipse-plugin installed. I want to decompile the classes within a jar-file. So I select the jar-file within Project-Explorer and click Decompiler in the Menu. However both decompilers (JAD and JD-core) are greyed out.
I also tried the steps shown in this blog on AVAJAVA Web Tutorials. I guess the blog is a bit outdated, however I can see within Windows-->Preferences-->Java-->Decompiler that Jad is correctly set up. But there is no JD-eclipse found within Preferences-->General-->Editors-->File Associations as you can see in the following image.. Now I right click the jar-file within Project-Explorer, but there is no such "Attach Source File".
Did I miss anything to set up the plugin?
EDIT: I´m using the following setup: Eclipse: Mars.1 Release (4.5.1); JadClipse 4.0.0; JDK 1.8
EDIT2: Forgot to mention that I use Tomcat and want to dive into the libraries from /WebContent/WEB-INF/lib. This is not working, I cannot further collapse the jar-files.

For Eclipse 2018-09 , the problem was related to " class without source
"
I had resolved this issue by going to:
Preferences
General
Editors
File Associations
Class without source
and setting decompliler viewer as default : see the following screen shot:

Obviously I mixed the actual JD-eclipse-plugin an a plugin called JadClipse for Eclipse which is a slightly different plugin from eclipse marketplace. Thus when I followed the installation instructions of JD-eclipse, I could set the options for the screenshot posted within the question. So I set JD-eclipse as default for both *.class-files with and those without source-code.
Second mistake I did was a pretty silly and obvious one, namely that I wanted to browse the jar-files from within WEB-INF-folder of my Tomcat instead of from within Java Resources. Thus I could not dive into the jar-files at all hindering me to get to the class-level and thus to decompile those classes contained within the jar.
I hope this helps anyone outside also having trouble with the plugin for eclipse.

I had the same problem but "class without source" did have decompliler viewer as default. So all I did was set class file viewer as default and then switched back and that fixed the issue.

I had to update all of my plugins. the Procyon decompiler has this symptom when running under java 11 or later.

Java project from existing ant build file doesn't appear as in version control

I have a repository in which I have a simple ant project (only the src directory and the build.xml file). I did a checkout of this project in a local copy. Then I opened Eclipse, created a "Java Project from existing Ant build file" and it worked fine. I can build, clean, run, generate javadocs, etc. However, my problem is that the source files in the packages, as well as the project itself, doesn't appear to be under version control in Eclipse. I can work with it fine from Cygwin, but not from the GUI.
The odd thing is that I have several regular Java projects, on the same repository which are synced fine by Eclipse, so it's not a version issue.
When I created the projects that work, I had to go to Team->Share Project... and Eclipse told me that they were already under version control and updated its configuration. However, in this current case, this isn't working. Any suggestion please?
EDIT:
I'm using svn 1.8.
UPDATE: I tried creating a regular Java project, and this time the version control looks fine, so it appears it's an issue related only to Java Project from Existing Ant build file.

The problem is that Eclipse doesn't know your project is using Subversion as a version control tool. You did a checkout outside of Eclipse, then you set up Eclipse as if this was a non-version controlled project.
To get Eclipse to recognize the project as under Subversion, you need to let Eclipse know. This means you should have said "File->New->Project, and select SVN->Checkout Project from SVN in the new project wizard. Then, Eclipse would have checked the project out in Subversion for you, and Eclipse would understand this project is in Subversion.
Unfortunately, I am not quite familiar enough with Eclipse to know how to tell Eclipse that the current project is really under version control. The best I could come up with was:
Right-click on the project and select Team->Share
Say this is a Subversion project you want to share.
Select the Repository to use
Select the folder where you want this project, and select the current folder.
You get the following warning:
Warning: The specified folder already exists in the repository. If you continue, that folder will be checked out to the existing location. Do you want to continue?
Your project will now be "checked out" over your current project. Everything should be okay because the files you have either match what is in Subversion or are modified versions of what is in Subversion.
You will be then asked to use the Synchronized view. Check "Yes", and then switch back to the Java view. Eclipse will now know your project is under Subversion and everything should work fine.
Note the use of Shoulds and Coulds. This is my way of saying that the advise given is done on an "as is" basis and I am not responsible for any damage done by following this advice, so please don't sue me.
It's basically your standard open source license.

Google Eclipse plugin recompile problem

I have installed Eclipse Helios(3.6) and Google plugin to develope app in GAE/J.Then created project and runned it sucessufull. Later made some changes in source code but it doesnt recompiled. Previous compiled version is in use. It doesnt compile until I make changes in appengine-web.xml. Could you suggest how to solve the problem please?
PS : I had the same problem in Eclipse 3.5. Also I added javac to SYSTEMPATH.

You could try the following:
the folder where your java files are in is a "source folder" (check it via project properties, "build path")
turn on "build automatically"? Can be found in Menu "Project"
Maybe refreshing your workspace automatically will help (Window->Preferences, and search for workspace)

The Project is automatically not builded or recompiled, when there are problems marked by eclipse. Take a look into the marker panel of eclipse and solve the problems.

What do I need to do to resolve bundle org.eclipse.rap.ui cannot be resolved in eclipse helios?

I don't know what I have done wrong but it seems pretty major yet I can't figure it out. I'm using Eclipse Helios to create a RCP / RAP application. I downloaded and installed the RCP / RAP IDE and I could previously launch RAP applications (although there were some runtime exceptions about something missing). Now when I create a new plug-in project using the rap hello world template I get 49 errors which I can resolve down to about 4 but the bundle org.eclipse.rap.ui cannot be resolved has got me.

by the looks of it, the RAP/RCP eclipse download did not include the required RAP target. I searched for the org.eclipse.rap.ui plugin, and its not in there. I would have expected it to be in a separate folder or something.
The RAP target can be obtained from here;
http://www.eclipse.org/rap/downloads/
I had to download a copy of the runtime and stick it locally in my file-system, and then create a new target from windows->preferences->plug-in->development->targets
and add a new RAP one, and point it to the downloaded folder.
in addition there seems to be an option to create a new target based upon a "software site" I tried by searching for "target" and selecting the Rap runtime target from the available software menu, and that seemed to work as well.
tldr;
I think the description of the RAP/RCP eclipse download is slightly misleading saying that all that is required to developer RAP/RCP apps is in the package.

It seems the RAP UI plugin is missing from your install.
First look at the plugins folder of your Helios install and check the presence of the org.eclipse.rap.ui plugin.
If not present, download again Helios RCP / RAP ide. It must be present otherwise there is a problem at eclipse.org but I am sure this is almost impossible ;-)
If present, open the plugin registry view Window -> Show View -> Other -> Plugin Dev -> Plugin registry and look for this missing plugin inside it.
If you see the plugin, right click on it and check Show Advanced Operations. Then right click again on it and select Diagnose. Here you should get information about the missing dependencies explaining why Eclipse can't find this plugin.
Hope this can help

Android Eclipse Classpath - want to add classpath container path but eclipse won't let me

I'm using Eclipse to learn to develop Android applications in Java. I haven't used Eclipse before.
The project I'm trying to use (supplied by OReilly as part of 'Android Application Development') is MJAndroid. When attempting to run the project, the Run fails, and the Problems tab mentions com.java.Object can't be found, and Eclipse asks me to check the build path. Clicking
Properties -> Java Build Path -> Libraries, the message 'Unable to get system library for the project' is displayed.
On a working project, Properties -> Java Build Path -> Libraries has an entry for Android 1.1, which if I click Edit, has the classpath container path of com.android.ide.eclipse.adt.ANDROID_FRAMEWORK.
It seems a simple matter of adding the correct container path to my non-working project. However Eclipse seems determined to make this as difficult as possible. No matter what I chose to add - jars, externals jars, variables, libraries, class folders, external class folders, nothing seems to take the form of 'com.android.ide.eclipse.adt.ANDROID_FRAMEWORK' that the 'Android 1.1' entry on the working app has.
How can I add this namespace to my project so it resembles the working one?
I'm quite sure it's a problem with Eclipse's somewhat odd user interface. Frankly there' nothing I'd prefer more than a file to modify and set such information - my background is in Python, and the whole eclipse environment seems an unnecessary burden.

I had faced the same issue when I imported a sample code downloaded from the internet. I am using android sdk 1.5 with 0.9 ADT plugins. Here is a simpler way to fix the andoid library reference issues
Right click on the project which has
issues and select properties
Select the appropriate Android build
(1.1, 1.5 or 1.5 with google api) and
say ok
Again right click on the project and
select "Android Tools > Fix Project
Properties"
Fix the imports once (if required)
Refresh the project and you should be
ready to go without any manual
editing

I faced this same problem after importing a project through GIT. The problem was that I didn't have the same target android platform installed, and the build path somehow got corrupted.
The first obvious thing i did was changing the target sdk in the project.properties, but even after cleaning up the project and Android Tools > Fix Project Properties, it didn't help and I was still getting the build error.
My solution after wasting close to 1 hour trying to figure this out?
RESTART ECLIPSE
Everything worked fine after that. Eclipse is pretty fickle. Only through years of experience you'll then understand her well. :)

Had the same problem and it turns out the Android SDK Location was not set which was a really simple fix. Go to Window->Preferences, click on 'Android' on the left hand menu, fill in the location of the Android SDK (e.g. C:\Program Files\Android\android-sdk) and click OK. Everything worked fine for me after that.
Found the answer in this set up guide: http://developer.motorola.com/docstools/library/Installing-Android-Dev-Environment/

Sometimes Eclipse can get a bit funny (technical term) with classpath container resolution.
You have a working project in your workspace, so you can rule out plugin installation issues. You could try opening the .classpath file (hidden by default, select the triangle in the top-right of the Package Explorer view, select Filters... and uncheck .* resources) and manually adding the container declaration.
`<classpathentry kind="con" path="com.android.ide.eclipse.adt.ANDROID_FRAMEWORK"/>`
You may then have to close the project and open it again (right-click->Close Project) before Eclipse recognises the change.
You may also find that there is an Android builder and/or nature. If you compare the .project files for the working and non-working versions you may see entries for Android builders/natures. Copying the relevant entries may resolve the issue.

sometimes, eclipse can help you.
In Android projects, click right button on the project-> Android Tools -> Fix Project Properties.
It's usefull in class path errors!!
Luck!

I would verify you have the correct version of Java installed as well as the Android SDK. I would recommend installing/reinstalling the ADT plugin in your eclipse, makes it alot easier to create the android project.
http://developer.android.com/sdk/1.5_r2/installing.html

Also. I guess the path of the Android SDK must be setup correctly. This happened when I was overloaded with projects and I decided to create a new workspace copying some existing stuff into it.
Seems that the new workspace requires you to setup these details too once again
Is that setup properly?