COMPUTER SCIENCE Summer 2006
Unit 1, Lab00 Hello Robot, your first program

Assignment: type in the program on page One-4. Save, Compile, and Run this first program.
- Use JGrasp to type the program into:
  1. File New - Java
  2. Save the program in your M drive in Unit 1. Do not save the program onto the Desktop.
  3. To Compile, use the + symbol
  4. To Run the program, use the running person symbol
  5. Whenever you make changes, Save your program again
Put in comments at the top of the program Your Name and Today's Date. Comments begin with the symbols // for a single line or use /* ... */ to enclose multiple lines of comments.
LabShell.java - an example first shell program - this program has all the necessary parts you need for your first programs.
Standard pieces of a Java program with JKarel, the Robot world
- import statement(s) at the top of the file. These bring or include previously written code from various libraries into your program.
  This shell program imports code from two libraries:
```
import edu.pace.World;
import edu.pace.Robot;
```
  Note that each import line ends with a semicolon (a Java convention)
- The beginning line of your program. All Java programs are enclosed in a class (a Java convention)
```
   public class LabShell {

      all your code goes here, in between the two curly brackets


   }
  
```
  You, the programmer, supply the name of the class, in this case the class name is LabShell.
  Very Important: You must save your program with the name you are using for the class with a .java added - LabShell.java
- The driver function for your program is always called main. This will change later on in the course when we study applets.
  main is used for Java applications, which all of our programs will be for most of the course.
```
     public static void main(String[] args) {
             
            Your code goes here in between the curly brackets

     }
```
  It's a Java convention to use the same wording all the time for this function main.
  Always use: public static void main(String[] args) - memorize it.
- Commands you use in your program:
  - World commands - predefined commands from the World class, such as World.readWorld("first"), World.setSize(10,10), and World.setSpeed(6)
  - Robot commands - predefined commands from the Robot class, such as karel.move(), karel.turnLeft(), karel.pickBeeper(), and karel.putBeeper()
  - See the API - the library - of classes and commands available. On the left of the API, click on World and scroll down to Method Summary. These are the commands available through the World class. Each method is defined as static, so the way you use these methods is World.methodNameI().
  - Click on Robot on the left. Scroll down to Method Summary for the methods available for the Robot class. There are methods without the static name. To use these methods, you create an instance of a Robot, for example karel, and then use karel.methodName()
  - In order to create an instance of a robot class, use
```
     Robot karel = new Robot();
  
```

COMPUTER SCIENCE Summer 2006 Unit 1, Lab00 Hello Robot, your first program

COMPUTER SCIENCE Summer 2006
Unit 1, Lab00 Hello Robot, your first program