Unable to Find Specific Libraries in Eclipse Project

Question

I just downloaded a FOSS (Java) project that I am attempting to build on my machine. I imported the project into Eclipse (it did not have its own .project or .classpath file) and let it build. It built almost all the way. However, I am receiving a number of errors where the compiler is "Unable to resolve [X]" where [X] is any number of org.eclipse.* packages.

So, I browse my filesystem and attempt to bring in the packages that make sense to complete the build (if the error is for org.eclipse.core.runtime.FileLocator, I attempt to bring in org.eclipse.core.runtime_3.5.0v20090525), yet I am still receiving the same errors.

I searched on Google but I am not any farther than I was when I started. Anybody have any suggestions?

Edit: The project is UMLet.

Edit 2: There is a plugin.xml file. Looks as follows:

<?xml version="1.0" encoding="UTF-8"?>
<plugin>
   <extension point="org.eclipse.ui.newWizards">
      <wizard
            name="UMLet diagram"
            icon="icons/umlet_eclipse.gif"
            category="com.umlet.plugin"
            class="com.umlet.plugin.wizards.UMLetNewWizard"
            id="com.umlet.plugin.wizards.UMLetNewWizard">
      </wizard>
   </extension>
   <extension
         point="org.eclipse.ui.editors">
      <editor
            class="com.umlet.plugin.editors.UMLetEditor"
            contributorClass="com.umlet.plugin.editors.UMLetContributor"
            default="false"
            extensions="uxf"
            icon="icons/umlet_eclipse.gif"
            id="com.umlet.plugin.UMLetEditor"
            name="UMLet Editor"/>
   </extension>

</plugin>

Answer 1

Since UMLet is an Eclipse plug-in/standalone RCP app the most likely cause is that the target platform (Windows -> Preferences -> Plug-in Development -> Target Platform) doesn't have all the required plug-ins that the project expects. The default target is the Eclipse you are running. The missing plug-ins need to be added to the target (i.e. find the missing plug-ins, add them to your Eclipse install, and refresh the target).

Answer 2

1. Make sure you use Eclipse PDE (plugin development environment), this will make your life easier with Eclipse-based projects.

2. Make sure you are using the correct version of Eclipse. Seems that you need 3.5.1. If you are using an older version of Eclipse, download a new one from Eclipse.org (get the PDT edition).