Loading class files

Question

I've been having a problem with something I have been making and I need some help.
I want to have a user use a file chooser to choose a class file and my program will run it for them in an internal frame. I can do it if I write the class into the code like:
SomeClass Share = new SomeClass();     
          JInternalFrame j = new JInternalFrame(Share.getTitle(), true, true, true, true);     
          Toolkit theKit = j.getToolkit();
          Dimension wndSize = theKit.getScreenSize();
          j.setLocation(wndSize.width/4, (wndSize.height/4)-50);
          j.setSize(wndSize.width/2, (wndSize.height/2)+100);
          j.setContentPane(Share.getContentPane());     
          j.setJMenuBar(Share.getJMenuBar());     
          Share.dispose();          
          j.setVisible(true);
          deskTop.add(jif);
But I want the user to be able to select what class goes in instead of SomeClass (as in the example)
I hope this made sense, but I really need the help! Thanks

Answer 1

If it's in the classpath & you remember to slice off the ".class" ending then buckman1's code should work well. However you may not be able to guarantee that the class is in the classpath! To do this use java.io to load the class file into a byte[] one way or another. Then use an instance of a subclass of ClassLoader (or SecureClassLoader) to load the class. This subclass must expose the method defineClass(String name, byte[] b, int off, int len) or equivalent so that you can load the class out of the byte array. Note that each instance of a class loader has it's own "namespace" for loaded classes! This may make it more tedious for you or be very useful if you need to load in two different classes called foo.class! (You will still have to use a common base class or interface.)