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Solutions to the Exercises: Getting Started

Exercise 1: What is leJOS?

• a: a graphical front end for LEGO MINDSTORMS™
• b: an operating system and Java-based language for the RCX
• c: an IDE for the LEGO MINDSTORMS™ programming language
• d: a toolkit for building LEGO MINDSTORMS™ robots

Exercise 2: What is the entry point for a leJOS program running on the RCX?

• a: public static void main(String[] args)
• b: public static void initRCXProgram()
• c: public static void mainRCX(RCXParams[] args)

Exercise 3: Where can I find additional information regarding leJOS?
Answer: there are several resources, e.g.

• The leJOS project
• leJOS FAQ pages
• The leJOS discussion forum
• Core LEGO MINDSTORMS Programming by Brian Bagnall
• Programming Lego Mindstorms with Java by Dario Laverde (ed.)

Exercise 4: What is the correct constructor call?

• a: Motor motor = new Motor(Motor.A);
• b: Motor motor = new Motor('A');
• c: Motor motor = new MotorA();
• d: none of these

Exercise 5: Change the simple sample application so that it displays "LEJOS" on the LCD.
Answer: change the line
TextLCD.print("DRIVE");
to
TextLCD.print("LEJOS");

Exercise 6: Change the simple sample application so that the motor runs backwards.
Answer: change the line
Motor.A.forward();
to
Motor.A.backward();

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