I have a jar library that I use for my app and I want to make changes to the source code.
After using JD-GUI to obtain the source code from the class files, I put the files in my project in Eclipse. But the source code contains many errors. For example, it says that the constructor does not exists, but the source code clearly has this constructor.
Please provide help. Thank you.
First thing, its never advised to change any built in jars which are provided for developers help.
Secondly, if you do want to make changes to it, use JD-GUI, take out the complete source code into a project, know the code, make the changes, compile the program to make sure all the dependencies before and after changes made, is ok so that no errors pop up.
Take the class files from the project and form the new jar and use it.
Related
I have a class BaseLoginDialog under a dependency which needs to be modified as it is not extendable out of the box. For this reason, I have created another file BaseLoginDialog under my project's module with the same package path as the original BaseLoginDialog. After adding some new methods in my own local BaseLoginDialog, I cannot use them anywhere in my project without IDEA complaining about the method not being declared. However, the project still compiles and the methods work fine on runtime. If I click the import to browse to the file, IntelliJ still links to the old file but it seems to correctly compile with the new one.
How can I go about fixing this issue? Always having error lines and red markers everywhere makes it confusing when coding.
Some background:
The project uses Gradle for the dependencies and compilation. Compiling and running works both with Gradle and with the IntelliJ run operation, it is only the errors being incorrectly displayed that is an issue.
The Grade file adds the required libraries as dependencies. Even though Gradle has both the source and class files, opening a file imported through Gradle still links to the class files. To get around this I also added the required files as sources under Libraries.
Any help would be appreciated, thanks!
EDIT:
Switched to use a Maven repo on the project, now I don't need to additionally add libraries anymore but this problem still persists.
If two classes of the same name and package exists in the classpath of an application, it's the one that is contained in the first dependency on the command line that gets used.
In IntelliJ, you can reorder dependencies, so you can put your local dependency before the other library. I'm not sure if that works with gradle projects, however.
But I don't think that's a good practice? Why can't you put the extra methods in a subclass, e.g. EnhancedLoginDialog, and use that one?
Or, if the original library is open source, fork it, make the changes and install it as a custom version, e.g. dialogs-1.0-CUSTOM-1.jar, and use this version in your project. And while you're at it, create a pull request for the library's maintainer to include your fixes in the next version :-)
I have resolved the issue.
The file I was copying into my local files was BaseLoginDialog. The file showing errors was my NewLoginDialog which extends LoginDialog which extends BaseLoginDialog. It seems that when IntelliJ goes to my NewLoginDialog, it sees that I have extended LoginDialog. Therefore it jumps into the library files and finds that LoginDialog extends BaseLoginDialog, now when it goes to find BaseLoginDialog, it uses the library files and ignores my local copy of BaseLoginDialog.
Essentially, once IntelliJ branches into a library, it does not move back out when looking for additional files if it can already find it inside the library.
To solve this issue, I simply also copied LoginDialog locally, even though it is identical (simply branched it and did not change anything). Now IntelliJ finds LoginDialog in my local files and as a result also finds BaseLoginDialog locally.
Hope this helps anyone having the same problem in the future.
I am working with Paho project for Android. According to the instructions, while testing Android sample app, it is required to have both AndroidService.jar and JavaClient.jar included in the project. I import them in Android Studio and the app is working perfectly.
However, and that is my problem, I want to edit these precompiled java classes. But the problem is that, since they are imported as .jar files and that they are already compiled, they are uneditable in Android Studio.
I have the source code of the libraries I want to include into the project. Unfortunately, when I import them in the Android Studio, I get bunch of errors (which I do not usually get when I import .jar files).
The methods I tried up until now are to copy the source java classes into the project by creating new classes with same names and content. I also tried to import the whole source project as the module to my project. I get same errors. I also know about this great fork of the Paho project which lets you just to import whole project in Android Studio and it simply works. However, the AndroidService classes are still uneditable.
As I said, I have the needed source code. I can generate these .jar files without any problem from the source and then import them in the project. That method works. But to edit the java classes, then to compile them, then to import them in the Android Studio to test everything, and to do it every time when I change something, is a bit tiring. That is why I am asking for help.
Please, let me know if you know some approach which will let me to edit these two "libraries" while I am still in Android Studio, so I can test changes I make immediately.
P.S. I have been Googling this so much and I believe that there is no ready solution for these online. However, If you find one, I will be really happy if you point to it.
Fist of all I have no idea why you want to edit the Paho Android Service because it doesn't make to much sense. You are able to overwrite every class if necessary. Any way you would need to change the Android Service build from Maven to Gradle to include the source into you project.
To help you out I have just done that and pushed to the "withSouce" branch of my repository. https://github.com/sandro-k/org.eclipse.paho.android.service.sample/tree/withSource
If you now want to replace the compile org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.0.2 with your sources as well you have to replace that with a local dependency as well.
Jar files are really just compressed (zipped) versions of .class files (and a few other essential documents). Class files are compiled .java files. The only way to edit these jar files would be to unzip the jar with a program such as 7zip or WinRAR, then decompile the class to get the source code, edit it, and recompile. Decompiling is a very difficult, time consuming process, and would require external software. Your best bet would be to continue the process you've been using.
Note: If you still wish to decompile, you might want to check out Cavaj, a free java decompiler. But beware, it may not return the exact source code used in the jar.
Sources: Experience
I have been searching for a long time on how to step through imported code classes in netbeans with no solution.
When debugging or stepping into the code, netbeans does not highlight and stop at the imported code classes being used. This is extremely inconvenient since the code I am working on is complex and stepping through is the only way to fully understand it.
I created a new project with existing sources. I have made sure that under window>debugging>sources I have added my working folders.
I also made sure the sources were added in the "runtime" classpath.
The compile classpath appears to be empty, I'm not sure whether that has something to do with it.
MORE INFO: In the debugging window while the program is paused, the main method profile from my imported class says it is reading from "Hidden source calls", but it is really just the normal imported code.
Why is this happening? Can anyone please help?
Folks,
One of the reasons you can get Hidden Source calls is adding in existing packages and java source code at the wrong directory level. You MUST add in the parent directory of the package not the child directory that represent the package name,
example if you have /home/torsi/java/src/torsipackage/com/main.java, you need to add in src, not torsipackage, you will now you made this mistake if you see listed in the top-level package name for your package.
Tom
Well I've not heard the term "Hidden source calls" before but I wonder if you're trying to step into third party code? If you want to step into compiled code it must have source associated I believe. I think it's possible to step into native code because they include the source somehow in the distribution for that exact reason. If you want to step into a library that's been developed by some other private entity you will likely not be afforded that luxury unless it's open source, and even then you may have to retrieve the source first.
Ultimately my point is that there is a difference between a .java file and a .class file. I believe it's possible to reverse engineer .class files but haven't done research on the topic.
If you want to step into code you didn't write odds are you'll need to change your code to work with the imported library or alternatively file a bug report with the developer.
I am a Java beginner, using Eclipse. I am trying to understand the NASA World Wind package. Specifically code that looks like this:
protected WorldWindow wwd;
protected StatusBar statusBar;
protected ToolTipController toolTipController;
protected HighlightController highlightController;
When I mouse over "WorldWindow" it says
Note: This element neither has attached source nor attached Javadoc
and hence no Javadoc could be found.
The code compiles and runs, though.
However, it points to a package in a JAR file. I can find the class it is referring to. But I cannot read the class file. When I double click on it, I get "Source not found" in the Class File Editor.
I want to understand how this code works. How can I read the class files within the JAR?
Reading the actual class files in the jar would require decompiling with a tool such as JD-GUI.
However a quick Google search returned the Javadocs for the entire library.
http://builds.worldwind.arc.nasa.gov/worldwind-releases/daily/docs/api/index.html
Enjoy!
Use a decompiler - try JD-Eclipse, an Eclipse plugin. After installing it, you should be able to click on the classes you want to view and be directed to decompiled code from within the JAR file.
The project you are using is open source, so you have a few options at this point.
Ideally you can associate the source code and javadoc with the .jar file in Eclipse. This will allow you to directly view (read only) the source and documentation for the library from within Eclipse. To do this, you will need to:
download the source code and/or the javadoc. These items may very well be included in the archive you used to originally download the project (either as a jar, zip, or expanded subdirectory).
inform Eclipse about the relationship between your compiled jar file and the source/javadoc. See this guide
☆ instant gratification ☆ View the source code directly from the project repository. The World Wind project appears to be accessible at http://worldwind31.arc.nasa.gov/svn/trunk/WorldWind/src/
You can decompile the compiled code. This solution is more useful if you're trying to investigate a closed source project or if you're debugging something unusual.
You have to "decompile" the class file into readable java code. There are several good decompilers out there, here is a very popular one JD-GUI.
Also if you are using an IDE you often can download the src files and attach them just to use as javadocs while writing your program.
I am trying to enhance a library. The library is in the Referenced folder of eclipse. I presume in that folder I can't just edit the code so I guess I have to import the whole .jar file as kind of a project, but how can I do it in eclipse .....
The right way to do it is to find/download the source code for the library. The ugly way to do it is to decompile the library.
After that, edit the source code, and run against your custom version.
You probably need some sort of Java code decompiler to get the source code for that library and then make an eclipse project based on its source. It will be tedious and you will need to setup the dependencies and all that. However you might want to see if the source for that project is already somewhere on internet, eg open source libraries. One better approach could also be extending that library by means of extending classes and that.