Error: The public type [ClassName] must be defined in its own file

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jumbala102

Error: The public type [ClassName] must be defined in its own file

in Programming Questions • 1 year ago

Hi, I just downloaded Processing 1.5.1 and I'm getting the following error: " The public type RedirectingMenuItem must be defined in its own file".

I have two classes:
- MyDemo, which is in the MyDemo folder and is named "MyDemo.pde"
- RedirectingMenuItem, which is in the MyDemo folder and is named "RedirectingMenuItem.pde".

When I run MyDemo, which creates RedirectingMenuItem objects, I get the error I mentioned earlier.

I know Java, but this is my first time using Processing and the PDE, so I don't know what I'm doing wrong as it seems that my files are named correctly and I keep getting this error no matter what I do.

Is there something obvious I'm missing here?

Replies(5)

PhiLho

Re: Error: The public type [ClassName] must be defined in its own file

1 year ago

All code files (.java and .pde) must be at the top level of the sketch folder. Processing doesn't support packages nor sub-folders.

PhiLho

Re: Error: The public type [ClassName] must be defined in its own file

1 year ago

Note that the error message you mention is usually displayed when you define two top-level public classes in the same .java file. Each one must be in a file of same name than the class, or one of it must be non-public.

Some remarks for those used to classical Java development.

- Because of the above said constraints (no package, few files as sketches are usually small), we rarely care about visibility rules (public/private/protected) and just stick to package protected (no scope declaration at all) to most entities.
- Even more as all classes defined in a .pde file are actually inner classes of the main PApplet class created with the name of your sketch.
- Of course, these remarks are not applies to libraries, following stricter rules (but often more relaxed than with regular Java libraries).

jumbala102

Re: Error: The public type [ClassName] must be defined in its own file

1 year ago

Thanks for the reply, but I don't think I understand your answer as I tried to fix my project with no success.

From what I understand, the main sketch folder is the folder "MyDemo", which is where both of my classes are. If I'm mistaken, I'd really appreciate it if you could give me the folder structure I'm supposed to have to make it work. MyDemo is supposed to call RedirectingMenuItem.

If it matters, I'm using Windows (but plan on using Processing on my Linux partition as well). MyDemo extend PApplet and is the class that draws some stuff and it also creates a menu bar (file -> new, file -> open, etc.). It calls RedirectingMenuItem, which extends java.awt.MenuItem and is used to create shortcuts for the menus.

If I define RedirectingMenuItem as an inner class of MyDemo, everything works fine, but it's not something that I want to do as my project is going to be huge eventually and it's going to become a mess if I make every class an inner class of MyDemo.

PhiLho

Re: Error: The public type [ClassName] must be defined in its own file

1 year ago

This is confusing.

" MyDemo extend PApplet"
If you use the PDE, MyDemo and PApplet are implicit (generated by Processing), you must not define them explicitly. See all the examples coming with Processing.

" extends java.awt.MenuItem"
You have to know that Processing and AWT/Swing are not mixing correctly, mainly for threading issues.
If you really plan to make a complex application, you might want to use Eclipse (or another IDE), create an application and use Processing as a library, with the PApplet in a frame. I haven't tried myself, but I saw some people reporting success in such setting. Then the menu / GUI elements can be outside of the sketch.

" If I define RedirectingMenuItem as an inner class of MyDemo, everything works fine, but it's not something that I want to do"
As I wrote, if you want separate classes and all, use pure Java directly. Processing is made for simplifying stuff and looking like a procedural language, by using inner classes and similar tricks. Classical Java is more convenient to structure large programs, but is a bit more verbose, which isn't a major problem with a good IDE.

jumbala102

Re: Error: The public type [ClassName] must be defined in its own file

1 year ago

Thanks to your latest reply, I removed " public class MyDemo extends PApplet" and everything works fine without changing anything else now.

The reason why I had typed that was that I was looking to solve another problem and after looking on Google, I saw someone recommend that I extend PApplet. I see now that it was wrong.

I think Processing might not be what I'm looking for, though, since I'm going to need some AWT elements (like the menu) and I need it to be stable and responsive.

Thanks a lot for helping me solve my problem!

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