You can automatically build and consume one project into another as a Java jar file in your Eclipse or Rational IDE.
This will save you from having to right-click and export every time you change code in the project that’s consumed. Or it can save you from having to write a build script just for this purpose, which I am embarrassed to say I've done (more than once).
<ul>
 <li>In your Eclipse or Rational IDE, right-click on the destination project and select Properties.</li>
 <li>Select Java Build Path and then the Projects tab.</li>
 <li>Click Add… to add the dependency project that you want to consume as a jar file.</li>
 <li>Next, in the left-hand side of the Properties dialog, switch from the Java Build Path to the item that says Deployment Assembly.</li>
 <li>Click Add… and select the project to be consumed as shown below 
 <a href="https://s3.us-east-2.amazonaws.com/codyburleson.com/images/2013/04/EclipseRadDeploymentAssembly.png"><img class="img-fluid" src="https://s3.us-east-2.amazonaws.com/codyburleson.com/images/2013/04/EclipseRadDeploymentAssembly.png" alt="" /></a> </li>
 <li>Finally, click Apply and OK.</li>
</ul>
Now, when I build my web app project, my <code>base22-commons</code> library (a separate project) is now automatically built and included in <code>WEB-INF/lib</code> as <code>base22-commons.jar</code>.

In your Eclipse IDE, you can automatically build and consume one project into another as a Java jar file. Here's how.

Automatically Build and Include One Eclipse Project Into Another