This web page was created to supplement a course offered by TheĬommons Attribution 3.0 Unported License.Greenfoot Karel J Robot Simulator Greenfoot - Karel J Robot Simulator See what error messages you can generate!. Once again, change the method call to the move method in your act method definition:įix any problems and make sure your act() method works. Try passing other parameters toĬhange the method call to the move method in your act method definition:ĭoes it work? If not, why not? What information does Greenfoot give you to explain what's going on? Try passing other parameters to move instead of 4.
#GREENFOOT SOURCE CODE HOW TO#
What's the problem here? When I pressed the question mark button, I got this message:Ĭan you tell how to fix the problem? Can you recreate the problem? You can also click on the question mark button for more information: When Greenfoot has trouble understanding your code, it highlights the area that's giving it trouble and generatesĪn error message. Which of the following are valid method calls? The square method takes an integer as a parameter and returns the Look at the following method header for a method called square: How do we know that 5 is a valid parameter for turn in the method call How do we know that 4 is a valid parameter for move in the method call Why do move(4) and turn(5) get invoked when we press the Act button? You call a method on an object when you want it to do something or to give you information.ĭouble-click on the Actor class and find the entries for move and turn as shown below: You call someone when you want them to do something or to tell you something. Method calls appear inside of method definitions. Here are method signatures for some of the methods in the Actor class: The method's name and the parameter types make up the method signature. The parameter list for the act method is empty.
#GREENFOOT SOURCE CODE CODE#
The source code above has one method definition: There can be many method definitions inside a class definition. A method definition contains the name of the method and tells what should happen when we call that method. A dictionary definition includes a word and tells what we mean when we use that word. Method definitions are contained in yellow rectangles inside the class definition. Notice that the class name Turtle begins with a capital letter. The class definition starts with the lineĪt the bottom of the green rectangle. The Turtle class is defined in the green rectangle.
Look at the source code for your Turtle class. Scenario download: trick-the-turtle.zip (save and unzip before To meet these learning objectives.work through this videosįrom now on, you should download the scenarios that go with the videos and code along with the video. What are the different ways that methods can be called in Greenfoot?.and you should know the answer to these questions Write a valid method call for a given method header.Find method headers by right-clicking on actors.Method Headers, Method Definitions and Method Calls By the end of this unit, you should be able to. GreenfootBook Page (includes links to book scenarios).Greenfoot Documentation (includes tutorials and videos).Java Tutorial Trail: Learning the Java Language Using Methods with Non-Void Return Types.
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