Develop Reference

How to solve java file mapped to not java file type text

I wanted to add a java class to a project, but I did a mistake and added it as a text file. Then, I removed it and tried to add it again as a java class, but unfortunately it doesn't work anymore. And I get the following error:
Unable to parse template "Class" Error message: ABC.java mapped to not java file type text
As I searched, I faced some solutions like
this one but I can't find File Type under Editor or anything similar that I can change as suggested in the solution.
Any help would be appreciated.
PS: I am using IntelliJ 2018.3.4.
Thanks in advance,

Go on File->Settings and a dialog will open. In that dialog navigate on the left part to Editor/File Types and then you need to choose from the section Recognized File Types Java Class and remove from bottom section the problematic extension (note you have a small minus button on the right)
https://www.jetbrains.com/help/idea/creating-and-registering-file-types.html

This is a variant of Markov's answer that worked in my scenario.
Try going to File->Settings->Editor->File Types and to the Recognized File Types tab. Click the "Auto-detect file type by content" choice, and delete the name of the file you are trying to create from the "File Name Patterns" section by using the minus button.

Select required file type in top list (Recognized File Types) -- do it for "Text files"
In bottom list (Registered Patterns) select undesired pattern -- "SomeFileName.java"
Click on "-" (Minus) button to remove pattern from the list
Repeat 1-2-3 for other undesired patterns
If desired, you can also do this manually by editing config file while IDE is closed. Because it's IDE-wide setting, it is not stored in .idea folder (which has project settinsg only) -- the file to look for is called filetypes.xml and shoudl be located in ~/Library/Preferences/IntelliJIdeaXX/options ( see http://devnet.jetbrains.net/docs/DOC-181 for other OS etc )

Certainly inelegant, but you can simply copy the contents of the file to the clipboard (ctrl-c or similar), delete the file (maybe make a temporary backup somewhere outside the project), then in IntelliJ go to the desired package, right click, select new, select Java Class, name it correctly, and then you can paste in the contents of your file (ctrl-v or similar).

IntelliJ does not show 'Class' when we right click and select 'New'

We're creating a new project in IntelliJ and must have something wrong because when we right click on a directory, select New and then get the context menu, Java based options are not shown. Currently get things like File, some HTML options, XML options.
We have assumed so far it's something we haven't configured correctly in the Project/Module configuration. The new module we are talking about is part of a multi module project. We created it using a Maven web archetype.
Any help configuring the project nature?
Edit: The answer is basic: 'That moment when you realise somethings not working because you haven't been clicking 'Apply'... :) We had a good laugh at ourselves when we discovered 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.

This can also happen if your package name is invalid.
For example, if your "package" is com.my-company (which is not a valid Java package name due to the dash), IntelliJ will prevent you from creating a Java Class in that package.

you need to mark your directory as source root (right click on the parent directory)
and then compile the plugin (it is important )
as result you will be able to add classes and more

If you open your module settings (F4) you can nominate which paths contain 'source'. Intellij will then mark these directories in blue and allow you to add classes etc.
In a similar fashion you can highlight test directories for unit tests.

Project Structure->Modules->{Your Module}->Sources->{Click the folder named java in src/main}->click the blue button which img is a blue folder,then you should see the right box contains new item(Source Folders).All be done;

I will share another interesting point. If you try to create a package with the reserved keyword then it will be treated as a normal directory and not a package. I was having this issue where I was creating a package named import and it was converting that to a directory.

Another possible solution is that the project name is not acceptable. For example, creating a project with spaces in the name does not block the project creation but the proper sources are not marked and when those are marked manually, I still was unable to create classes. Recreating the project with hyphens (-) instead of spaces corrected the problem for me.

Make sure you are not creating a package name which is same as predefined keywords in java like enum, int, long etc.
In my case I was trying to create a class under "enum" package. As soon as I changed package name to "enums" I was able to create class in it.

Had this issue too. Invalidating Caches/Restart did the trick for me. Please upvote so the the IntelliJ folks take this more seriously. This gives the IDE a terrible UI/UX experience.
https://youtrack.jetbrains.com/issue/IDEA-203100

There is another case where 'Java Class' don't show, maybe some reserved words exist in the package name, for example:
com.liuyong.package.case
com.liuyong.import.package
It's the same reason as #kuporific 's answer: the package name is invalid.

If you just created your project, let IntelliJ finish indexing your project.

You need to mark your java directory as Source Root ,
Right Click on Java directory
Select Mark Directory as option and click on the sub menu option Source Root

Most of the people already gave the answer but this one is just for making someone's life easier.
TL;DR
You must add the test folder as source.
Right click on java directory under test
Mark it as Tests
Add src/test/java in Test Source Folders
Thats it, IntelliJ will consider them as test source.

In eclipse, how can I find where in my classpath a type is coming from?

Maybe I'm misunderstanding something, but..
I want to be able to see that eclipse is getting Foo.class from a .jar (somewhere in the classpath) when it builds project B.
If I use the 'open type' (Ctrl + Shift + T) it seems that that just shows me all the places that Foo.class exists in my WORKSPACE?
Many thanks..
EDIT: I'm trying to find which jar is introducing a class into my code. It's not my jar. I don't have the source. I can't therefore open it and click it. I want a window that I can type in a type name, like 'Foo.class', and it tells me where that class is being brought in in my classpath. That must be quite simple? Ideally it would also tell me which occurrences later in the classpath were being hidden because it found the first one first. Does that make sense or am I talking nonsense?
EDIT: Guess I'm not making it clear. I don't have a piece of code that uses Foo. It's that somewhere in some included open source library something calls something calls Foo. So I can't highlight or right click anything. I guess I could write a piece of code that has it in? Seems a bit clunky..

Came here looking for the same, so though the question is two years old:
In eclipse Mars, if you press shift+control+T / ⇧+⌘+T on mac to bring up the "Open Type" dialog, the package as well as the name and path of the jar file is shown in the bottom of the window for a selected class.

Alternate Solution : particularly if you want to know the jar files which have needed class , you can search using WINRAR.
Use Find in WinRAR
i) Open WinRAR
ii) Open lib folder ( which contains all jar files ) in WinRAR
iii) Click on Find , type any classname (ex : ClassWriter.class )
iv) Click on OK
you will see all the classes which are named as ClassWriter.class in all jar files in lib folder.

Since there seems to be no good solution or plugin for this, I often create a dummy class in the root of my project:
public class Find {
public static void main(String[] args) {
System.out.println(
SomeClass.class.getProtectionDomain().getCodeSource().getLocation());
}
}
Then I just delete the class. A plugin would be nice :)

Look for .classpath file in your project.
OR
Where ever class Foo is used, go to that statement, while Ctrl key is pressed, left click the class name. Eclipse will take you to the location of Foo class. This will the Foo class eclipse is referring while building your code.

Right click on the class name, then select "Open declaration" (or just press F3), if you don't have a source attached, you can do it at that point. In the package explorer you have the functionality "Link with Editor" (a button with a couple of arrows going back and forward), that redirects you to the jar of the class. If you don't have the source, you still can use the "Link with Editor" functionality to see the propietary jar

search and replace text in all java files in a package

I am using a few functions in my application which i want to replace with other functions (to make it backward compatible)
My question : is it possible to find & replace some specific text in all java files in a package with some tool, or do i have to do it manually on every java file? I have a LOT of java files in the package.
For eg : i want to replace
getExternalCacheDir()
with something like
Environment.getExternalStorageDirectory + "/Android/data/<package_name>/cache/"
the IDE i'm using is Eclipse Helios. Any solutions?

Use Search - File... in Eclipse, search for getExternalCachDir() in *.java, then right click in the Search view, choose Replace All..., enter the replacement text, and click OK.

In eclipse, Just do
right click on function->Refector->Rename
or
select method + press shift+alt+R
This will change your method name through out the project.

Is there a way to locate a java file quickly and directly in Eclipse if I know its filename?

For example, I know I have a java file named "HelloWorld.java". I don't like to browse the package hierarchy to find it finally. I'd like there is a way that let me input this filename and open it directly.
Thanks.

CTRL + SHIFT + T for classes (.java files represent classes), and CTRL + SHIFT + R for all files.
A dialog will open where you can type the name of the class/file. Note that you can also use wildcards (*, ?) and camel case starting letters. For example, if you type HW, HelloWorld will be located.

Ctrl+Shift+R will give you an auto-complete panel.

Yes, just type Ctrl-Shift-R to find resources, meaning all files in your project.