Error

For the record any thing that Greenfoot doesnt recognize is posted as cannot find symbol- method (insert command here)

That is probably because Turn() and Move() are not supported Greenfoot methods. Maybe take a look at the Greenfoot API so see what kind of methods you can use? You can find it Here .

but why would the tutorial state to use this command: public void act() { if (Greenfoot.isKeyDown("left")) { turn(-7); } if (Greenfoot.isKeyDown("right")) { turn(7); } move(); }

It might have defined those methods somewhere else in the program, or it might be extending a specific class that gives Actors those functionalities. Is the actor in question extending a certain class? Can you find those methods in the program?

in fact i can! Check the wombats scenario and look at the source code for the wombats U should find the commands like turn() or move somewhere in there, it shouldn't take long to spot

The reason it can be used in the Wonbats scenario is because the program defines what Move() means: Like i said, Move() is not a default greenfoot command. The only reason Wombats can use it is because they have defined what it means and what it does. To add the functionality you want, try downloading the Mover class from this page and extending your Actor from that class, it will enable you to use Move and Turn like you want.

Those turn() and move() methods are defined in the starting Crabs scenario, in the Animal class (and Crab inherits from animal). I can think of a few possible reasons you might be having trouble:

• You've started from scratch rather than using the starting scenario (you can download it here: http://www.greenfoot.org/workshop/little-crab.zip)
• You are trying to call these methods from a class other than Crab
• You have accidentally stopped Crab extending Animal (the class file should have the line: class Crab extends Animal)

It's hard to say exactly which one without knowing more, but you are right that those methods should be available to you, and should work.

A sidenote: Java does not care about whitespace. What I mean is: in your initial post about the "error", you stated that you checked that the lines were indented correctly. The standard indentation is only for the programmer's benefit -- to make it easy to see that each open bracket has a close bracket. The following two sets of code do the same thing First: Second: Of course, this is also equivalent to "move();" by itself, because 'true' is always 'true'. But the point is: indentation is not something that affects the way a program works, or does not work; and by no means would cause compilation errors. In fact the method in the tutorial could look like this: You can even combine commands in one line like this: Actually, I prefer the one-liner for bracketted groups with only one command; and for groups with mutiple commands, I prefer to have the open bracket on a line by itself -- to match with the closed bracket; that way all brackets on the left of the code is paired. No lonely brackets as in the tutorial example you gave with the open bracket at the end of the 'if' statement line (same for the 'for' and 'while' statements).

Having the same exact frustration as Abstract. :( Trying to work through the tutorial #2. Have tried "little-crab" and "modern-crab" files. The command the tutorial instructs you to use does not work. (ie move/turn). In little-crab I get this error: "move() in Animal cannot be applied to (int)" So far, I find none of the replies remotely helpful. Disappointed. In modern-crab I get this error: "cannot find symbol -- method move(int)" Regardless as to what the issue is, I find it sad that one should have so much difficulty completing a simple tutorial! Tutorial 2 This is a place for beginners, is it not?

Well, I finally made a little progress. With little-crab I changed the line to move(); turn(3); Now, the crab will rotate, however it does not move forward. If there is an error in the move method, why do I need to de-bug that? Humph. I know enough programming to know when the error is me and when it is not. When I'm following a simple tutorial and follow it exactly, I know it is not me. I would like to see this tutorial revised/fixed.

Have you downloaded the most recent version of Greenfoot? I tried downloading the sample scenarios/tried the code myself and received no issues at all. If you continue to have issues, it might be a good idea to post all of your code so we can get a better look at what you are doing. I can assure you the issue doesn't lie within the tutorial, as the move() command works and is functional, but likely lies on your end, either with code, the version of Greenfoot you have, or some other problem that might have occured during installation.

Can anyone tell me if there is an issue with the move method here? /** * Move forward in the current direction. */ public void move() { double angle = Math.toRadians( getRotation() ); int x = (int) Math.round(getX() + Math.cos(angle) * WALKING_SPEED); int y = (int) Math.round(getY() + Math.sin(angle) * WALKING_SPEED); setLocation(x, y); }