Open a Class programmatically in a new Editor

I have the path of a class and after pushing a button in my pluginview, I want to open a new editor with this class in it. How can I do that. I know how to access the selected editor, but I dont know how to open a new texteditor programmatically.
If the class is already opened in an editor, I just want to make this editor the selected TextEditor. How can I do that programmatically?