Where is the default index.jsp file in a Java EE project in NetBeans?

In NetBeans by default, if you create a project with no added frameworks, no deployment descriptor (file web.xml) is provided.

To change it, right click on the project and select New>Other>web>Standard Deployment Descriptor(web.xml).

Now edit the web.xml file and set

<welcome-file-list>
    <welcome-file>newjsp.jsp</welcome-file>
</welcome-file-list>

in order to change the default to file newjsp.jsp.

Explicitly for Tomcat...

If no web.xml file is provided in the application, the default web.xml($CATALINA_HOME/conf/web.xml) of Tomcat is supplied to the application. This deployment descriptor has the following lines:

<!-- -->
<!-- If you define welcome files in your own application's web.xml -->
<!-- deployment descriptor, that list *replaces* the list configured -->
<!-- here, so be sure to include any of the default values that you wish -->
<!-- to use within your application. -->

<welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
</welcome-file-list>

That is why the index.jsp file is shown by default.

Make sure the JSP code file is not in the Web-Inf directory. It should be in the Web Pages directory.

If you are using NetBeans you need to click right the button on your project and then properties. A new pop up window will open, and on the left menu there will be a label called Run. Click there and then in the "relative URL". You should input:

./nameOfYourJspFile.jsp

And that's all!