interface.java

interface Printable{
  //it possesses no functonality within the methods.
  //It just contains method signatures.
  void Print();
  void printToPDF(String filename);
}

class MyClass implements Printable{
  public void Print(){
  // add functionality
  }
  
  public void printToPDF("example.txt"){
    // add Functionality
  }
  
  //additional functionality
}