Since a long time i have been searching how to debug a class file in Java.
For example :- consider a below code snipet.
Map map = new HashMap();
map.put("1","A");
map.put("2","B");
Now when if i want to understand internal working of put then it should redirect me to put method in HashMap class.
I have installed decompiler in my eclipse.
I set the breakpoint over put() but compiler does not comes till this point.
It skips the internal working of the method and points directly to next line defined by me.
Please help if there is anyway to debug class file
To debug the execution of core/JDK classes with breakpoints you need to add the source code of these classes.
For recent versions of Java, after unpackaging/installing the JDK,
you will find an archive at the root of the JDK folder such as src.zip for a Windows JDK.
Once you identified this file, make it accessible in any Eclipse projects by configuring the sources in the installed JRE section of the Eclipse preferences :
select the JRE (JDK generally) that you are using
click on "Edit"
select all JRE system libraries and click on "Source Attachement"
click on "External File" to select the zip file containing the sources you previously downloaded.
valid it by clicking "OK"
Here is a screenshot capturing relevant information :
In addition to the setup posted by davidxxx When in debug mode and the execution hits your debug point remember to use "step into" rather than "step over". "step into" will then get you into the .put() method.
You don't need a decompiler for this, not for classes in the JDK. Trying to use one might even cause you problems. Usually all you have to do is make sure your Installed JREs preference page contains a JDK and that you launch your Java Application using it, and not a JRE. The location of a JDK's sources are well known, so should be found automatically, and a JDK's .class files contain the debugging information to expose field names and local variables to the debugger while stepping.
Related
I know this question has been asked many times before, but none of the proposed solutions resolve my issue (or I'm not implementing them correctly).
I'm developing a plugin for OpenFire, and when I set a breakpoint in my plugin source Eclipse reports "Source not found". The JAR is built separate from the build of the OpenFire server. I've tried adding the JAR and specifying the source code directory, but no dice.
Here's the process I'm following: When I hit my breakpoint I'm clicking "Edit Source Lookup Path", clicking "Add", Java Library, User Library, click User Libraries, adding my library (tried both "Add JARs" and "Add External JARs"), and then specifying the folder that contains the source code. I've also tried:
Adding the source by selecting "File System Directory" instead of "Java Library"
Adding it by selecting "Workspace Folder"
In the Project Explorer, adding the source for my plugin to the Java Build Path
In the Project Explorer, adding my JAR as a Library and specifying the Source attachment
Thanks in advance for any suggestions.
Personally, I have no good experience in Eclipse JDT, when adding a source folder at the time it hits a break point. What I always prefer to do, is adding the source folder before debugging:
Select Project/Properties/Libraries
Select your library and "edit..." the source attachment
Select either the corresponding source folder or the zip/jar containing the package
After that, you should be able to open the source files in the virtual "Referenced Libraries" folder (directly below the "JRE System Library" folder inside the project), or when opening a reference to a linked class file from within the JDT editor. If you are able to access the source, then you should also be able to at least stop at the break point and see the corresponding source.
Else, you will have to check again, if the source folder is really valid: The source folder or source archive must contain the folder with the name of the root package of the library (e.g. the default Java "src.zip" inside the JDK folder also includes a corresponding "java" folder at its root). When in doubt, extract the archive and select the parent folder of the package you are interested in - sometimes source archives might be a mess or incompatible to JDT.
If this has been assured and it still doesn't work, chances are, that your linked source folder does not correspond to the compiled version of the library. Usually JDT will handle such inconsistencies fine, but if you try to open a source file, that is entirely different than the corresponding class file, you will encounter problems. In this case I would suggest either downloading the correct source version of the library, or recompiling the library from the source, if all else fails.
If opening a referenced source file from withing the JDT editor does work fine, and you are still unable to open the source files when a break point is entered during debugging, then most likely the class files are missing the line numbers of the corresponding source file. Again, you will have to recompile the library from the source in this case.
Finally, it is also possible to overwrite the default source lookup by specifying source folders or archives in the source tab of the launch configuration. But you should normally not need to do this, when your build path is configured correctly. From the Eclipse Help:
The Source tab defines the location of source files used to display source when debugging a Java application. By default, these settings are derived from the associated project's build path. You may override these settings here.
I had this very annoying problem for a long time but was finally able to solve it. In my case, a null pointer exception was being thrown somewhere in Java's Transformer.IsRuntimeCode(ProtectionDomain) function.
I didn't really need to know about this since the exception was being caught and handled, but eclipse would pause debugging every time this happened and tell me that the source wasn't available. As a result, I constantly had to keep pressing the button to continue code execution.
In order to prevent this from happening, I:
1. Clicked on the "Breakpoints" window at the bottom of the debugging
screen
2. Right clicked "NullPointerException"
3. Unchecked "Caught"
This prevented the debugger from pausing program flow during a caught NullPointerException.alt text
(source: SharpDetail.com)
And this another one as:
Eclipse doesn't crash. You're trying to step into a method, where eclipse doesn't know where to find the source (*.java) files and informs you about this. Here is how to tell eclipse where to look. Go to
Window->Preferences->Java->Installed JREs,select the JRE you are using and click Edit.
There, select all of the jar files in the list you see and and click Source Attachment....
In the window that shows up, select the fille src.zip, which is in your JDK folder (if you didn't uncheck it while installing the JDK). On the machine I'm on right now, that is
C:\Program Files\Java\jdk1.7.0_07\src.zip.
Save all your changes (possibly restart eclipse) and you won't see that error again.
Well it turns out the solution was anticlimactic. When Balder's recommendations did not work I tried debugging one of the stock OpenFire plugins and it worked just fine. I then created a new plugin from scratch, and by doing nothing other than adding the source to the project (Right-click on the project -> New -> Source Folder) it also worked just fine. I have no idea why Eclipse refuses to see the source for my original plugin, but I moved all my code and libraries over to the new plugin and debugging is working as expected.
Many times you put jar files in eclipse IDE as referenced libraries when binary version of application was downloaded. Usually done so by configuring the build path. But the binary does not have the source files. You have Binary version and source version of application.
One simple way is to download the source libraries that you also use maven to build the project.
Keep somehwere, may be inside your project workspace.
Now while seeing the class file (from eclipse, jar exploded) you may see the source not found, fine.... there is a button below and click on that, a new window opens and there select add external folder.
Reference it to the src folder of the source you downloaded(not the binary one) and kept somewhere as said above and it will show the class details from that.
I fixed this issue with doing the following:
Click at the menu Window - Preferences - Debug - Step Filtering And check all the packages like the following image.
(Step Filtering)
Then, debug again your project and thats it.
Best regards,
In my case, I had a breakpoint in the class declaration. I mean in the next line.
public class GenerateInterface implements JavaCall {
So, the debugger stopped in that line and showed the following message:
Source not found
I think unconsciously activate the breakpoint in that line.
I'm tracing into eclipse LTK plugin. I could set a breakpoint in some of the readonly java source for LTK. (for example ProcessorBasedRefactoring.java)
However, I couldn't set a breakpoint in some source files. (for example JavaRenameProcessor).
When I tried to set a method breakpoint, I got "Cannot create method breakpoint, method signature not available." error message.
What might be wrong? Why I can't set a breakpoint in some of the (binary) Java source file?
ADDED:
For a simple workaround to this issue, I just set a breakpoint wherever possible, and then open the java source to click a line. Then, I can use command-R so that eclipse executes up to the line that I point to.
ADDED2:
The breakpoint was there, but eclipse doesn't show it.
The other thing that I noticed was that the java file, just disappears from the IDE when I restart the debugger. And even when I reopen it in eclipse.
I got this error message - "zip file closed".
And then I can see the source code only when I trace into the method that the java source contains.
I believe that the class is compiled without debug information and/or the byte code is obfuscated.
Download java source code from open source website, the file's form is XXX.zip, not XXX.jar.
Build path -->c onfigure build path, enter the page, choose libraries, and open a jar file, find "Source attachment", and choose it, you can find a button is named "Edit" on the right, click it, and type the xxx.zip what you downloaded path into it.
back to your debug page, continue your work
Good luck! I hope my answer can help you.
I am using eclipse for java. When I debug, 'source not found' came out, is it because of javadoc? Where can i find javadoc in my desktop?
It appears your debugger stepped into a library class, and Eclipse cannot find the source for said library class.
You must tell Eclipse where the source files are located.
This is not related to javadoc
When you debug and when you go to inside of a method to debug and if you call that method through a jar file you will get this "source not found". If you can use source codes instead of that jar you will not get that and it will direct you to required source line in that method.
Eclipse telling you that source is not found has nothing to do with javadoc, but with the actual java files.
Most probably you do not have your project configured has a java project with source folders configured. To configure your project source folders do the following:
Right click on your project's name in the navigator view
Select properties
Go to Java Build Path -> Source
Make sure all your source folders are there.
After making sure that all source folders are correctly configured, you should move on to your debug view, and while debugging:
Right click in the attached process
Select Edit Source Lookup
Make sure your project is in the list, otherwise add it.
It can also happen that Eclipse is trying to display you a source file which is not from your project but rather from some other jar you're using or from the actual Java Runtime.
If that's the case and you still want to debug that source too you have to download the source (the correct version you're using) and use the previous 3 steps in the debug view to add that source to your debug environment.
One of the problems I'm running into is that my jar files and my source files don't match.
I'd like to:
Be Notified when when source and binary don't match (I think Visual Studio can do something like this...)
Set break points not by line, but by function. For example, set a break point at the entry of function foo().
I use eclipse mainly; so Solutions for eclipse would be most appreciated, but any IDE (or command line debugger) will do.
Thanks!
When developing just use and link to .class files that are saved by your IDE.
If your project starts to grow to a point where it's really useful to link to a .jar you're better off treating the jar's as separate projects.
Go to Project tab in Eclipse and then
click clean: Project->Clean…
click build automatically: Project->Build automatically
Use method breakpoints instead of line breakpoints. They can be set to halt on entering/exiting a method. You get them by double clicking the left editor side in a line containing a method declaration.
The debug information is limited to line numbers in the source file... I do agree that having a warning that the lines are wrong would be nice, but that would require more meta data in the jar than I think is available...
You might want to consider addressing the challenge with a change in your build process. This isn't exactly answering your question, but hopefully it will give you a strategy that will address the underlying problem.
When you generate the jar for deployment, also generate a jar with the binary AND source. For investigating the source code of a stack trace on the live server, set up a separate project in eclipse and have the binary+source jar be on the classpath. You may have to explicitly set the source code location back to the same jar (though I think Eclipse will just do this automatically).
Then you just have to add copying of the binary+source jar into the appropriate location in your workspace as you do your deployments (preferably with a deployment script).
If it's your server, you may want to even consider deploying the binary+source jar to the live server - that way you will always be able to get at the source.
I'm trying to accomplish a very basic task and somehow can't seem to find how... I would like to have my Eclipse environment set in a way that I can get help and documentation on any standard class/method in the JDK, like I used to do a few years ago with Eclipse on Windows, where having the cursor on a class name (e.g. PrintWriter), and clicking Ctrl+F2 would open up the Java documentation for the PrintWriter class.
Here's my environment:
Running OS X version 10.6.6.
Just downloaded and installed the Java Developer Package for Mac OS X 10.6 Update 4 from connect.apple.com
I have Eclipse Galileo installed.
Under /Library/Java/JavaVirtualMachines I have a file named 1.6.0_24-b07-334.jdk, which seems to be the new JDK I just installed. However, it's a single file, not expanded into directories and files. Right-clicking it and selecting "Show Package Content" shows me that deep inside it contains the files docs.jar and src.jar. However, not sure what I should be doing with the 1.6.0_24-b07-334.jdk file - should I leave it as is, or perhaps expand it to a full directory structure?
Under Eclipse Preferences, Java/Installed JREs I have JVM 1.6.0 (MacOS X Default) selected. However, the path points to /System/Library... and not to /Library...
Anyway, in Eclipse, putting the mouse over a class name, I get a brown dialog with a short explanation of the class. However, I don't know how to open up the full java documentation of the class. Also couldn't find anywhere in Eclipse a place to indicate where to take the java documentation from, nor which hotkey would bring the java documentation up.
I apologize for the many details, I'm just assuming they may be necessary to get a good answer.
Thanks!
/A
I've had the same problem — previously I had been able access Java documentation and source directly in Eclipse, but that disappeared after one of the Java updates from Apple last year.
My solution was to manually add the source and Javadoc to the JRE definition in Eclipse. Here's how:
Navigate to Preferences --> Java --> Installed JREs
Select your preferred JRE and click Edit...
Select the classes.jar library (should be the first one in the list) and click Javadoc Location...
Click Javadoc in archive
Set Archive path to /Library/Java/JavaVirtualMachines/1.6.0_24-b07-334.jdk/Contents/Home/docs.jar
Set Path within archive to docs/api
Click OK
now, optionally, you can set the source code too...
With classes.jar still selected, click Source Attachment...
Set Location path to /Library/Java/JavaVirtualMachines/1.6.0_24-b07-334.jdk/Contents/Home/src.jar
Click OK
In fact that 1.6.0_24-b07-334.jdk package is actually just a folder; it is treated as a single file by OS X but you can access its contents directly if you know the right path. What if you don't know what path the enter? You can browse the contents from Eclipse if you know this trick:
While attaching source code or Javadoc in Eclipse, click on the External File... or External Folder... button etc to bring up a Finder window
Navigate to your Java JDK folder (usually /Library/Java/JavaVirtualMachines)
You should see a list of your JDKs, for example 1.6.0_22-b04-307.jdk and 1.6.0_24-b07-334.jdk)
Press / on your keyboard to bring up the Go to the folder dialog box
Delete the / from the dialog box, and start typing the name of JDK you want to navigate. You can press Tab to autocomplete the name if you like.
Click Go
You are now browsing the contents of the JDK package; you can now click through to Contents/Home etc where you should see appledocs.jar, docs.jar, src.jar and other goodies.
For everyone finding this StackOverflow-Post and not finding the src.jar:
Apple removed it from the SDK and it's not supplied by default, however you can download it from Apple self at:
http://connect.apple.com/cgi-bin/WebObjects/MemberSite.woa/wo/5.1.17.2.1.3.3.1.0.1.1.0.3.9.3.3.1
http://danbim.blogspot.com/2011/01/java-for-mac-os-x-106-update-3-and.html
P.S. Apple account is required (free registration)
To bring up the Java documentation in Mac, move your mouse to the desired class, then click SHIFT+FN+F2.
By the way, you can find out the shortcut key from Preferences -> General -> Keys -> type "Open Attached Javadoc". Here's my screenshot:-
Under /Library/Java/JavaVirtualMachines I have a file named 1.6.0_24-b07-334.jdk, which seems to be the new JDK I just installed. However, it's a single file, not expanded into directories and files. Right-clicking it and selecting "Show Package Content" shows me that deep inside it contains the files docs.jar and src.jar. However, not sure what I should be doing with the 1.6.0_24-b07-334.jdk file - should I leave it as is, or perhaps expand it to a full directory structure?
From what I remember from Mac OS (I had to use one two years ago for some months) I think this is not really a "single file", it only looks so in the file manager application. Look if you can navigate inside it in the file-chooser dialog of eclipse where you can select the docs.jar for your documentation.
I was having a similar problem, and was having trouble accessing the Apple Developer page to download a local copy of the docs.jar. I went to Preferences > Java > Installed JREs > Edit, and then looked at the "Javadoc Location..." value for the jars. The Javadoc URI was still set to "http://java.sun.com/javase/6/docs/api/". When I changed it to "http://docs.oracle.com/javase/6/docs/api/" the tooltips started showing up again. Of course, this will only work when you are online.