Class loading in eclipse plugin <p>I made a <strong>eclipse plugin</strong> that acts on JavaProject. It needs access to information contained in the bytecode of the classes of the project and, therefore, I used a URLClassLoader (saying to it that the classes are in the "bin" folder of the project) to get the reference to classes and retrieve all the information I need . Unfortunately, when I call the method <code>loadClass("a certain class in JavaProject")</code> I get an error of this type:</p> <pre><code>org.eclipse.e4.core.di.InjectionException: java.lang.NoClassDefFoundError: javassist/bytecode/BadBytecode </code></pre> <p>I have found that errors of this kind are due to the fact that external libraries added to the JavaProject's <strong>BuildPath</strong> are not "known" by the classloader: classes of these libraries are used by JavaProject's classes </p> <p>In the previous case was used the <em>BadBytecode class</em> of library javassist in this statement of a class of JavaProject</p> <pre><code>public static void main(String[] args) throws NotFoundException, BadBytecode, IOException, CannotCompileException{ </code></pre> <p>So how do I make my plugin visible to the classes of external libraries imported into the java project?</p>