Questions on HW6-Spring08

• Follow the instructions carefully. Who said to write a constructor? Every method in TurtleDrawingFileIO is static; no constructor is necessary. You also cannot paste the constructor from TurtleDrawing into TurtleDrawingFileIO. Dawn Finney.

• I said you do not need constructors. TurtleDrawingFileIO should only have 4 methods (5 if you include the main) and no instance variables. You have completely change the main method to test your new methods. For the extractCommands method you need to do the following line

  LinkedList<TurtleCommand> commands = new LinkedList<TurtleCommand>();

  at the beginning of the method as well. Dawn Finney

• Yes. Dawn Finney.

• Yeah. You're supposed to figure this out. You should know this one. We've told you about static methods before and you've used them. Think about FileChooser.getMediaPath() and Math.random(). getMediaPath is a static method in FileChooser. random() is a static method in Math. Dawn Finney

• Misspellings? Dawn Finney.

• You have to import the GUI stuff. Dawn Finney

• Don't have the commands file open. I also found an error and uploaded the new version to the coweb but forgot to do it for t-square as well. Basically the extractCommands method isn't supposed to be declaring a new LinkedList. Dawn Finney

• What it says. Add new commands to the big LinkedList of old commands. Dawn Finney.

• The addMoreCommandsFromFile method will extract the commands from the inputted file and add it to the inputted list. You are required to have this method but you are not required to use it in the rest of the homework. I included it so some creative person could do something with it for extra credit. Dawn Finney

• See http://java.sun.com/docs/books/tutorial/java/javaOO/variables.html. Global variables are also known as attributes, fields or instance variables. Dawn Finney

    1public void drawCommands(LinkedList<TurtleCommand> commands){
    2  this.commands.addAll(commands);
    3  for(int i = 0; i < commands.size();i++){
    4   TurtleCommand command = commands.get(i);
    5   if(command.getType().equals("forward"))
    6    turtle.forward(command.getParameter(0));
         if(command.getType().equals("turn"))
           turtle.turn(command.getParameter(0));
         if(command.getType().equals("moveTo"))
          turtle.moveTo(command.getParameter(0), command.getParameter(1));
         if(command.getType().equals("setHeading"))
          turtle.setHeading(command.getParameter(0));
     }
    }

• turtle is probably null. Dawn Finney

• Inside the method. Dawn Finney.

• The incoming is new and the old is whatever is already there. TurtleDrawingFileIO does not contain any instance variables. Dawn Finney.

• Read the error. You should know how to handle this. Dawn Finney.

• Look above. Answered already. Dawn Finney.

• Make a TurtleCommand of type setHeading and addParameter of whatever heading needs to be passed into the setHeading method. Dawn Finney

public static void main(String[] args) {      
    JFrame frame = new JFrame();
    frame.setSize(400, 400);
    frame.setLocation(30, 60);
    
    TurtleSketchPanel sketch = new TurtleSketchPanel();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(sketch);
    frame.setVisible(true);
  }
}

• Look at the example provided in the homework more carefully. You are missing at least two lines. Dawn Finney

• Your turtle speed is probably 0. Dawn Finney.

• It's not confusing. Use two LayoutManagers in TurtleSketchPanel. Dawn Finney.

• You need to throw the Exception or put the statement in a try catch. Java is not "not allowing you" to do either of the forementioned items. You are probably just doing it wrong. Dawn Finney

• NO. That's probably part of BorderLayout. Dawn Finney

• You need to have the actionPerformed method in the TextListener too, just like what you did with ButtonListener. Dawn Finney.

• You need the actionPerformed method because it is an abstract method. Any class implementing an interface class is forced (by the Java com) to override all of the abstract methods. Dawn Finney