title: Re-building a deleted class file in Eclipse
body: <p>I accidentally deleted a .class (Java bytecode) file in my project (on the filesystem, not using Eclipse itself). Easy to fix, right? Just re-build it. But that doesn't work! Even if I select "Build Project" or "Build All" or "Build Automatically" from the "Project" menu, nothing actually happens on the file system, and I still get:</p>
  
  <pre><code>Exception in thread "main" java.lang.NoClassDefFoundError
  </code></pre>
  
  <p>I just want to re-compile this from the source code I already have!</p>
  
  <p>By the way, when I choose "Clean..." from the "Project" menu, Eclipse doesn't delete any files either. I have also tried re-importing the project into a different folder, but Eclipse just copies all the .class files and the problem persists.</p>