Assume the existence of an interface, actionlistener, with the following method : - actionperformed: void-returning, accepts noparameters define a class , guiapplication, that implements the above interface and has the following members: - an instance variable , doc, of type document - a constructor that accepts a document parameter used to initialize the instance variable - an implementation of the actionperformed method that invokes the method , save, with the document instance variable as the receiver and sends themessage "document saved" to system. out my code: public class guiapplication implements actionlistener{private document doc; public boolean save(){return true; }public guiapplication(document document){doc = document; }public void actionperformed() { doc. save(); system. out. println("document saved"); }}