Develop Reference

Where web.xml should be in a Java EE project using Intellij IDEA IDE?

In a Java EE project, where the web.xml file should be?
project/WebContent/WEB-INF
project/webapp/WEB-INF
project/src/main/WebContent/WEB-INF
project/src/main/webapp/WEB-INF
There is a way of changing that?

It depends the Dynamic Web Module facet you choosed and the configuration for the web resources in the project properties.

Migrate Java Web project from Maven to Ant

I have a Maven Web Application with Spring MVC and I need to convert it into a Java Web Application build with Ant. I am using Netbeans. The path structure should be the same? What configuration files should I add, remove, or change?
The reason of the change is beacuse I need to run the application without Internet connection.

How do we link multiple projects into the same web application

In a java based web-application that has multiple projects which are dependent on each other, where would normally we place configuration files like web.xml , log4j.properties and all? I am very new to web applications, but I pretty well know the package structure of a single project application. I am wondering how the application will look for the web.xml location and other configuration details in a multi-project environment?

You have to build a project and add dependency on all other projects
if you are using Eclipse
click right click on the master project -> properties -> Java Build Path -> Projects [tab]
here you can add other projects, good luck

As per my understanding multiple projects/modules have only one web based project and that require web.xml file, all other projects/module could be database/model or any other utility.

Difference between web projects with pom.xml and web.xml

What is the difference between Java projects having pom.xml and web.xml? Can projects have both these configurations at the same time?

They're completely compatible. As a matter of fact, they perform completely unrelated tasks.
pom.xml is the configuration file for Maven projects. One of its goals is to provide assistance in the compilation and building of a project when using Maven. You can think of it as an ant build.xml file or a makefile Make file if you're not familiar to Maven (actually, it can provide a lot more functionality)
web.xml is the Java EE web application deployment descriptor, where you specify for instance servlets, servlet mappings and other aspects of a webapp.
What is Maven from the Apache Maven site.
What is web.xml file and what all things can I do with it? question on SO.

The two files have nothing to do with each other.
pom.xml - Maven configuration file. Controls the build process for
the project
web.xml - Web application configuration file. Controls the deployment
and configuration of the web application
The POM file really shouldn't be deployed with the application, its just for the build process.

web.xml is an indicator that the project is running in some kind of servlet container (possibly even a full-fledged Java EE container).
pom.xml is an indicator that the project is built using the Maven build system.
Those two things are entirely orthogonal, so any given project can have none, one or both of them.

The Pom defines any dependancy libraries, it is part of Maven. This tells maven what jar files to download and store in the lib folder of your site.
Web xml is how your web project is configured.
They can both coexist as they do different things.

POM stands for "Project Object Model". It is an XML representation of a Maven project held in a file named pom.xml. http://maven.apache.org/pom.html
yes you can have both configurations at the same time.

The pom.xml is for configure your project with Maven.
The web.xml is use in all Java EE project under Tomcat for example.
You can use both, Maven is for compile and deploy your project, Tomcat is your server.

Java Web Project referencing another Java project

I have a Java Project, for which I'm now creating a Web interface, using a Dynamic Web Project from Eclipse. The Web project consists of a single servlet and two JSP's. Something like this:
/JavaApplication
/src
/lib
/resources
/WebApplication
/src
/Servlet.java
/WebContent
/WEB-INF
index.jsp
other.jsp
Now, I need to reference JavaApplication from WebApplication, in order to use its classes to process web requests. What's the best way to accomplish this ? My idea is to create a .jar of the JavaApplication, containing all the .class files, /resources, and /libs. In this way, I could include the .jar in the web application, and I could have a single .war file that contained the entire application.
What do you think? How is this problem typically solved ?
Note: I don't want to convert the Java Project into a Web project.

In Eclipse project properties, add the project to the Java EE Module Dependencies (Eclipse 3.5 or older)
or Deployment Assembly (Eclipse 3.6 or newer) entry in the project properties.
This way Eclipse will take care about doing the right thing to create a WAR out of this all (it will end in /WEB-INF/lib). No other configuration is necessary, even not some fiddling in Build Path.

Under Eclipse, you can declare Project References for a given project, the web application in your case. To do so, right click on your web application project, then go for Properties > Project References and select the JavaApplication project. This should allow you to call code from the JavaApplication project from the WebApplication without having to build a WAR. This is a solution for development.
For standard deployment (outside the IDE), you should indeed create a standard WAR. To do so, you'll have to package your JavaApplication as a JAR including the .class files and the files under /resources but not the libraries it depends on (JARs under /lib). These dependencies will actually end up in the WEB-INF/lib directory of the WAR, beside the JAR of your JavaApplication. These steps are typically automated with tools like Ant or Maven.

Connecting java app to web app for development :
right click on web project :
properties>project references> add the java project you want to refer
Now in properties tab of web project go to
properties>deployment assembly> add the project manually and run the app

Consider moving up to EAR level, if your web container supports that.
The tricky part with shared code is where should the common code be put. A copy pr web application? A copy in the web container? Overdoing the "share these classes" might end up in class loader problems.
If you are creating two separate web applications refactor common java code into a separate Eclipse project and refer to it from both WAR projects.
EDIT: Apparently I have misread the problem description, and thought you asked about an existing and a new web application sharing code.
If you have an Eclipse project with your application, and another with your web frontend, then you can let your application export the necessary resources which the "Export WAR" in Eclipse Java EE can wrap up in a jar file and put in WEB-INF/lib for you. You need to say this explicitly with a checkmark in Properties -> Java EE Module Dependencies for your web project. Expect you have to experiment a bit - this took me a while to learn.

Typically you would create an API interface using remote service beans from the Java application that expose the methods that you want to invoke in the web application. You would include a proxy of the API interface with your web application that calls the remote service bean in the Java application. Remember that you will need to register the remote bean in the web.xml file.