I have been at this problem for a few days now, don't know why it is still happening. I have tried other solutions that have been posted on stackoverflow but no luck.
Below the following code is from the book crafting interpreters in java.
In IntelliJ 2019.4 this error always pop up when I am trying to run the .jar file.
Error: Could not find or load main class com.jam.Jam
Caused by: java.lang.ClassNotFoundException: com.jam.Jam
I have built the .jar file and setting the main class as com.jam.Jam and the class path for the .jar file as /home/username/Jam-Programming_Language/src/com/jam/Scanner.Scanner.
This is the layout of my project directory.
The following solutions I have tried:
Solution 1
Open Project Structure
Select Modules, then click on the module for which you want the
dependency
Choose the Dependencies tab
Click the '+' at the bottom of the page and choose the appropriate
way to connect to the library file. If the jar file is already
listed in Libraries, then select 'Library'.
and
Solution 2
Go to the Project Structure, click on Modules, and click on your
Module
Choose the "Dependencies" tab
Click the "+" button on the right-hand side and select "Jars or
directories..."
Add the directory(ies) you want (note you can multi-select) and
click OK
In the dialog that comes up, select "classes" and NOT "jar directory"
Make sure you're using that Module in your run target
It had no effect apparently. Any clue on what I should do?
Edit: Uploaded wrong screenshot, replaced screenshot.
Thanks to CrazyCoder for pointing out the errors in my project (silly mistakes). It seems that after I have resolved those mistakes.
I had to follow the solutions I have posted then rebuild the .jar file.
Afterwards I need to mark the src folder as a source root folder (right click folder -> Mark Directory as -> sources root)
Edit Configurations if pointing to wrong main class.
Set Project compiler output (File -> Project Structure -> Project) to a folder designated to hold the output (any folder basically in or outside the project).
The error says, it is trying to run: com.jam.testfile. Your class is called: com.jam.Jam.
Click the dropdown where it shows "testfile" with a little red X on it. Select "Edit Configuration." For the "Main class", select "com.jam.Jam". That's it!
BTW, the little red X means there is some problem with your configuration.
Related
I have been trying to figure this one out for a bit, not coming up with the right approach. I read through this question, which I'd already tried, but it's not working quite right.. using IntelliJ EAP 142.4675.3
What I am trying to do, is to debug a junit test using a jar (extending the Provider class) file I've placed into JAVA_HOME\jre\lib\ext. I want that jar to be debuggable as well.
The problem is, if I attach my source directory as the source for a jar, then, in a stack trace, when I click the named file (containing a method I wish to view), IntelliJ asks me to choose between two of the same file, presumably because it knows about the source (it's in a module in my project) and it's also been told about the source via the jar source path I added.
I tried adding the provider.jar to the project module dependencies tab, which caused intellij no end of grief. Reverted back to having it in jre\lib\ext, and, in the Platform Settings->SDKs->1.8->Sourcepath tab, I added the module sourcepath. This lets intellij step into the .java file for the jar, vs the .class file, but, when it does so, I now get a banner at the top of my code windows which says "Alternative source available for the class xxx" and there's a combobox at the RHS with the module name listed twice (in the latest EAP, it actually lists the module and the jar [same name as module, with .jar]). And, as mentioned earlier, the IDE asks which which (of the very same) file I wish to edit when I click a file in the stack trace.
Clearly, there is something not quite right.. what am I missing? I find it odd that the ide will not open the source code when stepping into the jar until I attach the code as above, but, when I do, it sees it twice.
So let's start from scratch:
File > New Project, choose "Java Module", fill the form:
Bypass the form asking about the kind of project (webapp etc) by clicking on "finish"
you now have a project with a src dir:
right click the 32910506 directory and choose "New" then "Directory" and create a new directory named lib.
drag and drop your 2 jars (sources and code) to this directory (I will use common-lang for this example), beware to copy, not move:
now right click on src, choose "New", "Java class", name it App:
right click your "code jar" and choose "Add as library":
in App type psvm then hit TAB to get a main and fill it like this:
right click on your "code jar" and choose "Open library settings":
click "+" and choose "Attach file or directory" and select your "sources jar":
Now if your Ctrl+click on random in App, you should end up to the method source:
Put a break point in the random method:
Now right click App, choose "Debug App.main()", you should end up to the previous breakpoint:
Used: idea 12.1.6 under linux
Here's what I'm seeing:
Normally I can choose "New Java Class" but for some reason I'm not getting this option. I created this project by opening an empty directory and building it out from there. I've seen this question, but that answer didn't help me. Here's my module settings:
Even if I open my pom.xml directly as a project, it still has this problem. How do I fix this?
The directory or one of the parent directories must be marked as Source Root (In this case, it appears in blue).
If this is not the case, right click your root source directory -> Mark As -> Source Root.
For some reason, intellij didn't recognize my directories as packages. If I created something directly from the java directory, it would give me the correct options. I fixed this by deleting everything under java/ and recreating it. This may be an intellij bug.
This happened when I was trying to add classes to a generated package using xjc plugin.
Intellij allows to add classes only to packages which are correctly names and have the "source root" status.
Can be fixed as-> right click on the directory where you're not able to add classes:
Mark sources root
refer image for clarity
This worked for me :
Right click the java folder (myproject/src/main/java)
Click "Mark Directory as"
Click "Source Root"
Right click the myproject folder (myproject/src/main/java)
Click "Mark Directory as"
Click "Source Root"
So basically had to mark some inner folder as Source project and alter mark parent project again as Source project..
Hacky way but this worked for me.
What is this ant build error in eclipse?
When I click the Ant Build I have the error message shown below.
Build failed
Reason: Unable to find an Ant file to run.
Could you please help me solve it?
Quoting from here
Create a new project in Eclipse
After the project is created, look in the package explorer window pane on the left and right click on the src folder.
There are two methods for the next step, you could either add a New > Class, and then copy and paste everything from your old java file to the new class (make sure the class name is the same), or the better route would be to Import.
After clicking Import, select File System under the general folder. Click Next.
Browse for the java folder where your source files are located. Once you click ok, it will add all of the source files to the right pane.
Select which files you want to add and click Finish.
Now if you look at your Package Explorer window you should see the source files. Now just compile them, and the error shouldn't appear and you can run them just like before.
This question already has answers here:
Eclipse: The resource is not on the build path of a Java project
(16 answers)
Closed 5 years ago.
I am getting The resource is not on the buildpath of the project when I am trying to "Organize imports" or trying to access any class properties.
I am building my project with ant.I tried to configure my buildpath in javabuilpath -> Projects but it is not showing me my src folder there.I am not able to use quick assist (ctrl + space) and class related properties because of the same reason
and it does not show me any syntax errors also while i am writing my code.
please help me.
thanks
I just hit this problem myself, and it's baffling. You get it in a bunch of different places as you try and treat a Java file as, you know, a Java file but Eclipse hasn't figured out that it's actually a class within your project. The reason it doesn't know (or the reason it didn't know in my case) was because the directory hasn't been marked as a source directory for the project. So you need to tell the project configuration that the file is in a directory that holds source files. Here's how:
Open your project's properties.
Under "Java Build Path", click on the "Source" tab.
Click "Add Folder..."
Find the folder where you have the unrecognized java file. (In my
case it was test->Java)
Put a check by the folder. (I put it only by "java" and not by
"test" given that the test folder holds a lot of other stuff.)
Click ok, click OK again, perhaps refresh, and you should be good to
go.
Your src folder shouldn't appear in the Java Build Path -> Projects tab. Rather, it should appear under Source tab.
Try imorting the class files as external jar.
What icon is used for the file? If it is an outline J eclipse doesn't recognize the file as being a source file of the project.
If so, you need to declare the parent folder of your package a source folder, i.e. if the path looks like ".../src/my/package/MyClass.java" the "src" must be declared a source folder (right click -> Build Path -> Use as Source Folder)
This is a total newbie question, but I can't figure it out so I figured that I would ask it here and see what happened.
Here's the problem: For my java programming class, we are supposed to download a .class file created by our instructors containing a custom-made class with methods that we are supposed to use in an assignment. I already know all of the code to create the class within my actual program, but I can't figure out which directory to place the .class file in. I have tried the src and bin folders inside the project directory, and even placed it directly into the project directory, but nothing seems to work. My instructors say to just put it in the same directory as my java program, but they are using jGRASP. What am I doing wrong?
You can place the class file anywhere, just be sure to add its directory to your project's build path. Right click on the project, then properties at the bottom then build path, til you find add class folder.
You have to create a project, or open your project if you have it already, then, while you are in the Java view, select File > New > File. It will open a window, you can create your file there and choose in which project folder do you want to put it. If in that window you press the button "Advanced >>" it will give you the option to "Link to file in the system", check it, and then you can browse your folders to the downloaded file.
I don't know if this solves your problem, it's what I understood from your question.
Your instructors class file must be in the build-time and the run-time class paths for your project to use it. Instructions assume that you are on a PC.
Run-time class path setup
Create a directory (perhaps C:\JavaRoot\classes). I will refer to this as the Classes directory.
If one does not already exist on your PC, create an environment variable named CLASSPATH
Add the Classes directory to your CLASSPATH envoronment variable
Download the class in question and put it in the Classes directory.
Build-time class path setup
Right mouse on your project in eclipse.
Select "Properties".
Select "Java Build Path".
Select the "Libraries" tab.
Click the "Add a Class Folder" button.
Browse to and select the Classes directory you created during "Run-time class path setup" above.
Click the "OK" button
For Eclipse use the following:
Project > Properties > Java Build Path > Libraries (Tab) > Add External Class Folder (Button)
If you have a configured project in Eclipse and you manually added a Java class file in some of the project directories, you just need to refresh the project for Eclipse to recognize it:
Right click in your project (in "Project Explorer" view) -> Refresh