Help for Karel J Robot

NEWS: This free JJ version of Karel J Robot is brought to you by PublicStaticVoidMain.
We would like to thank Joseph Bergin for his efforts integrating Karel and JJ.
You can find the online version of Joe's Karel J Robot manuscript here.

Our new Karel Intro slides are now available at:
http://www.publicstaticvoidmain.com/sij/JJKarel/SIJLessonJJKarelIntroSlide1.html

Now, for a little HELP on the buttons:

[CheckIt] (for registered accounts) Compiles any Java program
[Karel]: Compile a Karel J Robot program
[Help]: This current page you are reading
[>>>FullEdit]: Larger font for editing your program
[clear]: Clears edit and error areas
[RunIt]: Enabled after a clean compile (first press [Karel])
[prev]: Go back through your list of 'prev'ious [Karel] programs
[next]: Enabled after pressing [prev]
[History]: (for registered accounts) a complete History of all your programs

Karel Exercises

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JJ                                      
JJ    This text contains the following sections 
JJ    with exercises following each section          
JJ                                       
JJ    1. Initial Karel program             
JJ                                       
JJ    2. Reading input & making choices    
JJ                                       
JJ    3. Putting down & picking up beepers 
JJ                                       
JJ    4. Using more control structures     
JJ                                       
JJ    5. Creating and Using classes        
JJ                                       
JJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJ

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JJ                                       
JJ  1. Initial Karel Program             
JJ                                       
JJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJ

When you first login to Karel J Robot the following program
appears in the codeIt window:

////////////////////  begin program  ///////////////////////
// Does a 'square dance'
// A robot named karel, starts at the intersection
// (or the corner) of 2nd Street and 3rd Avenue,
// facing East with 1 beeper in it's pocket

Robot karel;
   karel = new Robot(2, 3, East, 1);

karel.move();
   karel.turnLeft();
   karel.move();
   karel.turnLeft();
   karel.move();
   karel.turnLeft();
   karel.move();
   karel.turnLeft();
   JJS.outputlnString ("My little square dance is finished.");
////////////////////  end program  /////////////////////////

************************
** Exercises on a robot  
************************

Once you have run this program, make some changes and
watch karel follow your commands.

1.1  The current program has karel doing a
one-by-one square dance. Modify the program
so that karel does a two-by-two square dance.
That is, karel is to move two positions forward
before turning, and then follows a two by
two square pattern.

1.2  Modify either the original program or
your solution to exercise 1.1 above so that
karel turns around and backtracks over the
same exact same square pattern he just followed.
That is, for the first square karel moves
counter-clockwise.  When karel finishes the
first square, karel is to move clockwise back
over the exact same square.

NOTE: karel has no turnRight command, but
can eventually turn right by making many
turnLeft commands.

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JJ                                       
JJ  2. Reading Input & Making Choices    
JJ                                       
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Below is a program that shows how to use the
JJ System (JJS) for input of a String value.

To try it in the JJ environment do the following:
First click on the [clear] button under the left window,
and copy and paste the below  code into that window.
Then click on the [Karel] button, and then on [RunIt].
Finally, click the [Start] button on the RunIt page.

////////////////////  begin program  ///////////////////////
//Does show input to redo dance
  String answer;
  Robot karel;
  karel = new Robot (2, 3, East, 1);
  karel.move();
  karel.turnLeft();
  karel.move();
  karel.turnLeft();
  karel.move();
  karel.turnLeft();
  karel.move();
  karel.turnLeft();
  JJS.outputlnString ("My little square dance is finished.");
  JJS.outputString ("Should I do it again?  'Y'es or 'N'o: ");
  answer = JJS.inputString();
  JJS.outputlnString(answer);

if (answer.equalsIgnoreCase ("Y") ||
      answer.equalsIgnoreCase ("yes")) {
      karel.move();
      karel.turnLeft();
      karel.move();
      karel.turnLeft();
      karel.move();
      karel.turnLeft();
      karel.move();
      karel.turnLeft();
  }//endif
////////////////////  end program  /////////////////////////

*****************************
** Exercises with inputs 
*****************************

Once you have run this program, make some changes 
and watch karel follow your commands.

2.1  Modify the current program so that karel
outputs (using a JJS.outputString command) the
message "I am 3/4 of the way there" after karel
turns the third corner. Do this for both squares.

2.2  Write a program for karel to make either
a one-by-one or a two-by-two square depending
on the input provided after the program has
started.  That is, use an input command to
ask how big of a square karel should make.
There are only two possible values for the
input: a one for a one-by-one square, or
a two for a two-by-two square.

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JJ                                       
JJ  3. Putting down & picking up beepers 
JJ                                       
JJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJ

Below is a program that shows how to use the
putBeeper and pickBeeper commands to put down
and pick up beepers.

///////////////////  begin program  //////////////////////
// Does show put down & pick up of beepers
   Robot fred;

fred = new Robot(2, 3, North, 1);
   fred.move();
   fred.putBeeper();
   fred.move();
   fred.move();
   fred.turnLeft();
   fred.turnLeft();
   fred.move();
   fred.move();
   fred.pickBeeper();
   fred.move();
   fred.turnOff();
///////////////////  end program  ///////////////////////

*****************************
** Exercises on beepers  
*****************************

Once you have run this program, make some changes 
and watch karel follow your commands.

3.1  Modify the above program so that fred
outputs (using a JJS.outputString command) the
message "I am putting down a beeper on the
corner of ___ and ___" after putting down
the beeper.  Also have fred output a message
when he picks up a beeper, such as "I am
picking up a beeper on the corner of
___ and ___".

3.2  Modify the second "square dance" exercise (1.2)
by placing a beeper while moving counter-clockwise around
the square, and removing it while moving clockwise around
the square.

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JJ                                       
JJ  4. Using more control structures     
JJ                                       
JJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJ

Random Robot Race involves two robots karel and carol
that race ten blocks according to a random simulation.
Every race is different; watch a few of the races.
The code involves a while loop with two choices within.

////////////////////  begin program  ///////////////////////
// Name Ann Onymous
// Does Random Robot Race
// Shows more robots & loops with ifs
   int i;
   Robot karel;
   Robot carol;
   int karelsMoves, carolsMoves;

karel = new Robot (1, 1, East, 1);
   carol = new Robot (2, 1, East, 1);

i = 18;
   karelsMoves = 0;
   carolsMoves = 0;
   while (true) {
      if (Math.random() < 0.5) {
          karel.move();
          karelsMoves++;
      }//end if
      if (Math.random() < 0.5) {
          carol.move();
          carolsMoves++;
      }//end if
      i = i - 1;
      if ((i == 0) || (karelsMoves==9) || (carolsMoves==9)) break;
   }//end while
////////////////////  end program  /////////////////////////

*****************************
** Questions on the Robot Race  
*****************************

Once you have run this program, take a close look at the code.
If you wish, run the program many times.
Answer the following questions:

Q4.1 Is it possible that neither robot makes it completely
across the Robot World?

Q4.2 Is it possible that both robots make it completely
across the Robot World?

*****************************
** Exercises on control  
*****************************

Once you have run this program, make some changes and
watch the robots follow your commands.

4.1 Modify the program so that exactly one robot wins the race.
    Does your program favor one robot over the other?
4.2 Introduce a third robot Darel to the race
    and also a fourth robot Farel and race them.
4.3 Race robots 'uphill', from South to North.
4.4 Race robots up (North), and then across (East).
4.5 Race robots diagonally from SouthWest to NorthEast.
4.6 Race robots entirely around a square track.
4.7 Make some 'crop patterns' of your own design:
    rectangles, triangles, crosses, circles, stick-people, 
    etc, by placing beepers in various locations.
4.8 Cellular Automata: BIG Challenge!
    Create robots that put down patterns of beepers
    corresponding to the 'Rules' of the very recent book 
    'A New Kind of Science' by Stephen Wolfram.
    Rule 110 is shown on the sample page of the book at:
    http://www.wolframscience.com/preview/nks_pages/?NKS0032.gif
    Rule 250 is very regular; Rule 30 is 'rather' random.
    HINT: you could use 4 robots marching together. Robots Rule!

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JJ                                       
JJ  5. Creating and Using Classes
JJ                                       
JJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJ

Below is a program that shows how to write
classes in your JJ+Karel programs. You may
name your class anything you want, but it
has to extend JJKarelMainClass. Also, you
must write a public void method named
jjKarelStart, which is the "main" method.

Thus, there are two requirements for
writing a JJ+Karel program using a class:
1. Your class must extend JJKarelMainClass
2. You must write a public void method
named jjKarelStart() (it does not get
passed any values).

Following is an example of creating a new robot class.
It is a big jump from the previous examples! 
Recall that the original robot only made left turns; 
here we extend it to make right turns also, and later
we can extend it further.

////////////////////  begin program  ///////////////////////
public class MyRobotClass
       extends JJKarelMainClass {
// Does show classes and methods

public void jjKarelStart() {
   // Does a "right square dance"
      MyRobot carol; 
      carol = new MyRobot (2, 3, East, 1);
      carol.move();
      carol.turnRight();
      carol.move();
      carol.turnRight();
      carol.move();
      carol.turnRight();
      carol.move();
      carol.turnRight();
      JJS.outputlnString ("My right square dance is done.");
   }//end void method jjKarelStart

class MyRobot extends kareltherobot.Robot {

public MyRobot ( // Constructor of MyRobot
      int str,         // starting street number
      int ave,         // starting avenue number
      Direction dir,   // starting facing-direction
      int beeps) {     // starting number of beepers 
      super (str, ave, dir, beeps);
    }//end Constructor

public void turnRight() {
      turnLeft();
      turnLeft();
      turnLeft();
   }//end method turnRight

}//end class MyRobot

}//end class MyRobotClass
////////////////////  end program  /////////////////////////

*****************************
** Exercises on Classes  
*****************************

Once you have run this program, make some changes 
and watch carol follow your commands.

5.1  Modify the above class to add a method uTurn,
which makes the robot reverse its direction, i.e.
make a 180 degree turn.

5.2  Write a program that has carol start at the
corner of 4th Street and 4th Avenue and move in
an outward spiral using only right turns until
a total of 10 turns have been made.

NOTE: When using classes,
all commands must be inside of methods, and
all methods must be inside of classes.

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