Develop Reference

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.

Trouble with JAR creation

sorry if this is a simple question but I'm having trouble exporting my java project into a JAR file. I'm getting the following error:
JAR creation failed. See details for additional information.
com/appiancorp/plugins/capitalize/theFunction [in Capitalize] is not on its project's build path
Unable to get package fragment root: Capitalize/com/appiancorp/plugins/capitalize/theFunction/Capitalize.java
com/appiancorp/plugins/capitalize/theFunction [in Capitalize] is not on its project's build path
I guess I need to add the "theFunction" class to my buildpath? But I don't understand how to do that...Thanks for the help
EDIT:
I'm using files from the StringTokenizer class in my project and thus importing stuff from java.util.StringTokenizer. Could the problem be I'm not adding that class to the JAR files?
Darby

The missing class belongs to a jar from the company(3d party)
http://www.appian.com/
you need to find that missing jar and add it to class path

Java Package Vs Folder-Structure? what is the difference

I would like to know What are the difference between folder-structure and package used in Eclipse IDE for Java EE development.
When do we use which one and why?.
Whats should be the practice
create a folder structure like src/com/utils and then create a class inside it
create a package like src.com.util and then create a class inside it
which option would be better and easy to deploy if i have to write a ant script later for deployment ?
if i go for the folder-structure will the deployment is as easy as copying files from development to deployment target ?

If you configured stuffs correctly. Adding a folder inside src, is same as adding a package from File > New Package.
So, it's up to you, whatever feels comfortable to you -- add a folder or create a package. Also, when you put stuffs under src the package name starts from subfolder. So, src/com/naishe/test will be package com.naishe.test.

Basically there is no difference, both are the same.
In both the cases, the folder structure will be src/com/utils.
and in both the cases, you will need to mention
package com.utils;
as first line in the class
Since it doesn't have any difference practically, it won't make any difference to ant script.

"Packaging helps us to avoid class name collision when we use the same class name as that of others. For example, if we have a class name called "Vector", its name would crash with the Vector class from JDK. However, this never happens because JDK use java.util as a package name for the Vector class (java.util.Vector). So our Vector class can be named as "Vector" or we can put it into another package like com.mycompany.Vector without fighting with anyone. The benefits of using package reflect the ease of maintenance, organization, and increase collaboration among developers. Understanding the concept of package will also help us manage and use files stored in jar files in more efficient ways."
check out http://www.jarticles.com/package/package_eng.html for more information on packages

create a package like 'src.com.util'
That sounds like a mistake. The package name should be 'com.util', and 'src' is the name of the source folder.
Other than that, I fail to see what the difference is between your two choices. The result is the same, right? Just different steps in the GUI to arrive at it. The wizard to create a new package in Eclipse is just a wrapper around creating the appropriate folder hierarchy within a source folder.
You don't need to create empty packages at all, you can directly create classes (the package will be created automatically if it does not already exist).

A package is automatically "source folder" where folder is just a normal folder.
When you compile an Eclipse project, all files in source folders are compiled but not in regular folders (unless those regular folders a)

folder structure or to be specific source folder in eclipse is meant just for eclipse but package is universal irrespective of any editor..

How to add a class to a .jar library?

I need to add a class to a .jar library but I can't figure out how to do it.
I have a library named netty-3.1.5.GA.jar but for some reason its missing a class I need
(HttpTunnelClientChannelFactory.java).
I have found that class on a repository but not as part of the library. So how can I 'inject' it? The class I need to add is using other classes that exist in the library.

You don't need to add it to the jar, you need to add it to the classpath of whatever it is you're running.

You can use the jar tool to update the jar file: you will need to manually create the appropriate package directory though. Try this:
jar uf netty-3.1.5.GA.jar HttpTunnelClientChannelFactory.class
will add it to the root package. If you need it to be set up in a package directory you should create the directory structure and then add the file with a path.
EDIT: that should be .class, not .java.

Getting a resource in a different project using classloader

Using the ClassLoader#getResource(), I need to access a file that is present in a project other than the one where my current code resides. How can this be done?
I'm using eclipse.
Directory Structure:
Root
|-project1
| |-package
| |-myResourceFile
|-project2
|-package
|-myCodeFile
I'm trying to get myResourceFile from myCodeFile, using myCodeFile.class.getClassLoader().getResource("../../project1/package/myResourceFile") but its always returning null. I do not want to add project1 to the classpath of project2. Though adding that also did not work.
With regards,

It's a bad idea to attempt to read files from another project like that because it ties you to exactly that directory structure. You already did the first step in decoupling the projects by using getResource() instead of using the java.util.File API so you can go the full way as well.
In Eclipse you can add other projects to a projects' build path (Project Properties -> Java Build Path -> Projects). You should be able to read the other projects' files now.

If you are using maven, then you can specify project1/package as a resource folder in the pom.xml of project2. You can theen use Classloader getResource method to get the resouce
http://maven.apache.org/plugins/maven-resources-plugin/examples/resource-directory.html