Java Training Robocode: Java Can Be Fun

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Java TrainingRobocode Java Can Be Fun

• Written by Jeff Smith(portions borrowed from
  RoboCode website)

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Introduction

• Java Libraries
• A common task for a Java programmer is to
  identify a library, download it, and then learn
  how to use it
• Javadocs are useful here
• Google is too! For example, if I wanted to use
  JDBC (Java Database Connectivity) and needed a
  code example, I could Google this
• JDBC Java example
• Or
• JDBC Java tutorial

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RoboCode What is It -1

• Robocode is a Java library and is free
• Was originally developed by Mathew A. Nelson in
  2001- 2005
• Now been taken over by Flemming N. Larsen in 2006
• Was created as a tool for teaching Java
• You can either extend a simple Robot class or an
  AdvancedRobot class
• You guessed it, AdvancedRobot extends Robot
• Well use the simpler class, Robot, for our
  exercise

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RoboCode What is It -2

• A Robot/Tank battle simulator
• Basically, you can extend a Robot class and
  implement a few methods (like fire()).
• In a few lines of code, you can define how your
  Tank will track and fire on enemies
• You can compete in the Battle Simulator
• You define a simple (or not so simple, if you
  choose) Robot class and the RoboCode Simulator
  does all the graphics and time steps for you
• You start out with a certain amount of energy,
  and you
• lose a lot of energy when you get hit by another
  robot
• some energy when you fire your gun
• a little energy as time ticks by

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RoboCode What is It -3
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RoboCode Intro -1

• Body - Can move ahead and back, as well as turn
  left or right.
• Gun - Mounted on the body. Can turn left or
  right, and fire energy bullets.
• Radar - Mounted on the gun. Can turn left or
  right. Generates events when other robots are
  detected.

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RoboCode Intro -2

• run() method
• The main method of your Robot class
• This method gets called by the Battle Simulator
  in turns or time slices
• your robot gets to run, then your opponent gets
  to run
• Some things to do in the run() method
• Move ahead or back
• Turn
• Scan
• Fire

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RoboCode Intro -3

• How do I know what Robot methods I can call?
• Javadocs, of course!
• Ive put a link to the Javadoc for Robot.java on
  the Fun Stuff pagehttp//www-ad.fsl.noaa.gov/a
  c/javazone/FunStuff.html

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RoboCode Intro -4
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My First Robot Class -1
package sample import robocode. /
MyFirstRobot by Mathew Nelson. Moves in seesaw
motion, and spins the gun around at each
end / public class MyFirstRobot extends Robot
public void run() while (true)
//run this loop forever ahead(100)
// Move ahead 100 turnGunRight(360) //
Spin gun around, scan back(100) // Move
back 100 turnGunRight(360) // Spin gun
around, scan
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My First Robot Class -2
/ Fire when we see a robot our
gun radar are pointed in same direction /
public void onScannedRobot(ScannedRobotEvent e)
fire(1) //fire with power1
/ We were hit! Turn perpendicular to the
bullet, so our seesaw might avoid a future
shot. / public void onHitByBullet(HitByBulle
tEvent e) turnLeft(90 -
e.getBearing())
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My First Robot Class -3

• Basically, my first robot goes forward 100 units
  and then backwards 100 units (some kind of
  movement is important so you can avoid being hit
  by another Robots gun!)
• It also turns its gun (and radar) around in
  circles, so it can detect enemy robots
• When an enemy is detected by this radar
  rotation/scan, the onScannedRobot() method is
  invoked automatically by the Battle Simulator
• Since the gun and radar are in sync (pointing in
  the same direction), all you need is a call to
  the fire() method when you detect the enemy robot

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Robot Class Events Methods -1

• In OOP, event methods are generally invoked by
  some external piece of code (perhaps another
  class)
• You just write the code to respond to the event
• onScannedRobot() - called when the radar detects
  a robot
• onHitByBullet() - called when the robot is hit by
  a bullet
• onHitRobot() - called when your robot hits
  another robot
• onHitWall() - called when your robot hits a wall

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Robot Class Events Methods -2

• You generally dont need to invoke these event
  methods directly (in your own code)they are
  invoked on your behalf by the Battle Simulator
• You can choose whether or not to override these
  event methods in your own Robot subclass
• For example, if you want to execute some special
  code when you hit a wall, implement an
  onHitWall() method.
• If you dont care about hitting walls, dont
  implement the method

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Other Robot Class Methods -1

• turnRight(double degree)
• turnLeft(double degree) turn robot by a specified
  degree
• ahead(double distance)
• back(double distance) move robot by the specified
  distance
• Note ahead() and back() returns early if robot
  hits a wall or
• another robot. So if you made a call to
  ahead(9999999), the
• call would return once your robot hit either a
  wall or another
• robot (it wouldnt go ahead forever).

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Other Robot Class Methods -2

• turnGunRight(double degree)
• turnGunLeft(double degree) turns the gun,
  independent of the vehicle's direction
• turnRadarRight(double degree)
• turnRadarLeft(double degree) turns the radar on
  top of the gun, independent of the gun's
  direction (and the vehicle's direction)
• getHeading() returns your current heading in
  degrees

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Other Robot Class Methods -2

• turnGunRight(double degree)
• turnGunLeft(double degree) turns the gun,
  independent of the vehicle's direction
• turnRadarRight(double degree)
• turnRadarLeft(double degree) turns the radar on
  top of the gun, independent of the gun's
  direction (and the vehicle's direction)
• getHeading() returns your current heading in
  degrees

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What Does This Robot Do? -1
public class MysteryRobot extends Robot
public void run() turnLeft(getHeading())
for () ahead(99999)
turnRight(90)   public void
onScannedRobot(ScannedRobotEvent e)
fire(1) public void onHitByBullet(HitByBu
lletEvent e) turnLeft(180)
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What Does This Robot Do? -2

• This robot gets its initial heading, then turns
  left by that amount so that it faces straight
  NorthturnLeft(getHeading())
• Next it starts moving Northahead(99999)
• Whenever it runs into something, the ahead()
  method returns and this code turns it right by 90
  degrees and starts moving in this
  directionturnRight(90)
• Whenever it detects an enemy in front of it, it
  firesfire(1) //fires with powerlevel1
• Whenever it is hit by an enemy bullet, it goes in
  the opposite directionturnLeft(180)

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Installing Robocode

• You download the Robocode JAR (3 Mb) from
  herehttp//robocode.sourceforge.net/
• You install it by running the JARjava jar
  robocode-setup-1.2-Beta.jar
• (or whatever the name is of the JAR file you
  download)

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Running Robocode -1
Go To Battle Menu, New to choose robots for
your battle
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Running Robocode -2
After you select your robots, click the Start
Battle button, and then the battle begins!
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Robocode Editor
Go to the Robot Menu/Editor, to open the Editor
window. Select File Menu/New to create a new
robot. You can also use Eclipse to create your
robots.
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Robocode and Eclipse
Go to the Options Menu, Preferences, and then go
tothe Development Options tab. Add you Eclipse
project to the list. When you create a New
Battle, remember to hit F5 (refresh)
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Debugging Your Robot

• You can watch your robot in action by creating a
  New Battle
• You might want to compete against Sitting Duck
  in order to test some of your code
• To see how your robot does against a sample
  robot, you can create a new battle and watch the
  action.
• If you want to see the final results (for
  example, how many times out of 10 did you win),
  just minimize the robocode window. The game keeps
  going, but MUCH faster.
• You can generate messages to the robocode console
  window by calling out.println like
  soout.println(Here is my message)
• To view the messages, click on your robot name
  (button) in the upper right of the Robocode window

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Exercise

• Create a Robot subclass that can defeat the
  sample robot, MyFirstRobot
• You can look at the other sample robot classes to
  get ideas on how to do this
• You can either use the built in RoboCode editor
  or Eclipse. Put your code in a package with your
  name in it
• For example robocode.jeff or gov.noaa.robocode.jef
  f
• This way, we wont have package/class name
  conflicts when we have tournaments