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Unable to find or load Main Class in Intellij 2019.4

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.

Proper way to configure IntelliJ to use source code for decompiled jar

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

How can I avoid this Ant Build error?

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.

how to open specific Jframe as a main jframe?

when I run the project compiler says BUILD SUCCESSFUL but not any window is appear. when I runt the project I want to start main_window as a default window. but I have no Idea how to setting up this.

If you are creating a jar file (as I assume you will be doing from your previously deleted question), the main class would be specified by the jar file's manifest.
e.g., the manifest file, named MANIFEST.MF could contain a line looking like:
Main-Class: gui.main_window

Right Click on the Netbeans tool-bar. An drop down menu should appear. Select Customize and scroll down through the options until you see Run File. Drag the button onto the tool-bar. Now select the main_window.java and hit the Run File button.
The IDE should run only the file.

Eclipse will not run programs or detect errors

My eclipse seems to be pretty screwed on my laptop. Whenever I load a program up from College, it does not detect the errors or anything. Also now when I attempt to run the program, it won't allow it; i'm given the message
unable to find an ant file to run
Anyone able to help me out?

1-Create a new project in Eclipse
2-After the project is created, look in the package explorer window pane on the left and right click on the src folder.
3-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.
4-After clicking Import, select File System under the general folder. Click Next.
5-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.
6-Select which files you want to add and click Finish.
7-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.
By creating the new project, you're making sure Eclipse knows where your source files are located (in ./src) so that it can compile your code in that location.