Java Programming

Objectives Introduce Software Engineering Concepts Introduction to Object Oriented and Java Programming Provide Context for Software in FRC Robotics Provide Foundation Interacting with Programming Team

Agenda Introduction Philosophy Object Oriented Java Syntax FRC Robotics  Libraries  Tele-operated  Autonomous

Introduction Mr. Rich Vitkus  BS Computer Science at Rensselaer Polytechnic Institute  Manager of Enterprise Architect, Lowe’s Home Improvement  3 years FLL, 4 th year FTC, 6 th year FRC Evan Vitkus  VP Programming  2 years FLL, 2 nd year FTC, 2 nd year FRC

Philosophy Computers do what you tell them to do, not what you want them to do. Different results mean either the software, the system, or the data has changed Reuse ideas, libraries, and code. Test and debug systematically with as much information as possible. Programming is not art it is engineering. The standards and process are essential to success.

Object Oriented Consider an airport system in the real world. It consists of many different parts which work together to get work done  Control tower, airplane, runways, fuel trucks, security agent, … When we build a software systems, some of the software objects have corresponding names  Class ControlTower, class Airplane, class Runway, … Reduces “representation gap” between software model and solution we are building  Improves comprehension, communication, and predictability

Object Oriented – Real World Object Consider an airplane in the airport system. What is important? Real world objects have information  Airplanes have a model number, serial number, speed, altitude Real world objects also do things  Airplanes can land, take off, change speed, turn, …

Object Oriented – Software Object Have names corresponding to the real world system  Class Airplane Store information – attributes  modelNumber, serialNumber, speed, altitude Perform actions – methods  land(), takeOff(), changeSpeed(), turn()

Object Oriented – Software Object An object bundles data (attributes) and code to perform actions (methods) into one, cohesive unit Airplane speed model land() takeOff() //Java source code class airplane { private int speed; private int model; public void land() { … } public void takeOff() { … }

Object Oriented – Project Simple dice game  Each player rolls two dice ten times  The player rolling seven or more the most times is the winner

Object Oriented – Project Identify the real world objects in the game  Game  Player  Die

Object Oriented – Project Identify the attributes of each object in the game Game  dice  players Player  name  score Die  value

Object Oriented – Project Identify the methods of each object in the game Game  play Player  takeTurn  incrementScore  getScore Die  roll

Object Oriented – Class and Instance Class  Definer: A blueprint that stores the definition for instances  Creator: A factory for creating software objects of one kind Instance  Instantiated (created) by a class  Occupies space in computer memory  Retains values of attributes  Has behavior An object bundles data (attributes) and code to perform actions (methods) into one, cohesive unit Die value roll() die1:Die value=3

Java Syntax - Attributes Java is strongly typed Two basic types in Java  Primitive – int, double, boolean, char, etc  private int value;  Object – created from classes  private Die die1; Variables– attributes which can change values Constants – attributes which do not change values  private final int SIDES = 6;

Java Syntax - Methods Methods can perform actions, have parameters, and return values Public void setName(String playerName) { name = playerName; } public int roll() { value = (int)(Math.random()*SIDES) + 1; return value; }

Java Syntax – Control Structures - Conditional If statements handle boolean (true or false) conditions if (i == 3) doSomething(); if (i == 2) doSomething(); else doSomethingElse(); if (i == 3) { doSomething(); } else if (i == 2) { doSomethingElse(); } else { doSomethingDifferent(); }

Java Syntax – Control Structures - loops Loops repeat a segment of code // validate a boolean condition then execute while (i < 10) { doSomething(); } // execute then validate a boolean condition (always // run at least once do { doSomething(); } while (i < 10); // execute a specific number of times for (int i = 0; i < 10; i++) { doSomething(); }

Java Syntax – Project public class Game { private Player player1; private Player player2; private Die die1; private Die die2; private int score; public void play() { for (int i = 0; i < 10; i++) { score = die1.roll() + die2.roll(); if (score > 7) { player1.incrementScore(); } for (int i = 0; i < 10; i++) { score = die1.roll() + die2.roll(); if (score > 7) { player2.incrementScore(); } if (player1.getScore() > player2.getScore()) { System.out.print("Player 1 wins"); } else { System.out.print("Player 2 wins"); }

Agenda Introduction Philosophy Object Oriented Java Syntax FRC Robotics  Robot  Libraries  Tele-operated  Autonomous

FRC Robotics – Object Oriented Software Objects correspond to Real World Objects Reduces “representation gap” between software model and solution we are building  Improves comprehension, communication, and predictability An object bundles data (attributes) and code to perform actions (methods) into one, cohesive unit

FRC Robotics Input Process Output

Lunacy ull.wmv ull.wmv

Robot – Photo 1

Robot – Photo 2

Robot – Photo 3

FRC Robotics - Libraries FRC Javadoc   import edu.wpi.first.wpilibj.Joystick;  import edu.wpi.first.wpilibj.RobotDrive;  import edu.wpi.first.wpilibj.Victor;  import edu.wpi.first.wpilibj.Servo;  import edu.wpi.first.wpilibj.Jaguar;  import edu.wpi.first.wpilibj.Compressor;  import edu.wpi.first.wpilibj.camera.AxisCamera; Getting Started with Java for FRC

FRC Robotics – Teleoperated Human Players control the robot Software controls the robot Event Loop Input  JoySticks  Sensors  Timer  Camera Process  Calculations Output  Speed controllers  Solenoid

FRC Robotics – Teleoperated Human Driver and Human Robot  Eyes open  Eyes closed

FRC Robotics – Teleoperated Pseudo Code

FRC Robotics – Autonomous No Human Players Software controls the robot Input  Sensors  Timer  Camera Process  Calculations Output  Speed controllers  Solenoid

FRC Robotics – Autonomous Human Robot  Vision  Touch  Time

FRC Robotics – Autonomous Pseudo Code

FRC Robotics – Questions

FRC Robotics – Appendix Slides removed to reduce to 75 minutes

Java Syntax - Methods Setters and Getters  Setters are a public method to set the value of private attributes  Getters are a public method to get the value of private attributes Player Public void setName(String playerName) Public String getName() Public void setScore(int playerScore) Public int getScore()

Object Oriented – Concepts Cohesion – strongly related responsibilities of a software component Encapsulation – hide information or details  Attributes are private (only exposed to the class)  Methods are public (exposed to the world) Polymorphism – multiple methods with the same name which operate on different data  print(file)  print(integer) Inheritance – a generalization, specialization hierarchy. Extend or override functionality and data from a parent (super) class  boy is a human is a mammal

Object Oriented – Project Game PlayerDie PlaysHas Rolls

Dice Game Code - Die public class Die { private final int SIDES = 6; int value; public int getValue() { return value; } public int roll() { value = (int)(Math.random()*SIDES) + 1; return value; }

Dice Game Code - Player public class Player { private String name; private int score = 0; public void setName(String playerName) { name = playerName; } public String getName() { return name; } public int getScore() { return score; } public void takeTurn(Die die1, Die die2) { int roll; score = 0; for (int i = 0; i < 10; i++) { roll = die1.roll() + die2.roll(); if (roll > 7) { incrementScore(); } public void incrementScore() { score += 1; }

Dice Game Code - Game public class Game { private static Player player1 = new Player(); private static Player player2 = new Player(); private static Die die1 = new Die(); private static Die die2 = new Die(); public static void play() { player1.takeTurn(die1, die2); player2.takeTurn(die1, die2); if (player1.getScore() > player2.getScore()) { System.out.print("Player 1 wins " + player1.getScore() + " to " + player2.getScore()); } else if (player1.getScore() < player2.getScore()){ System.out.print("Player 2 wins " + player2.getScore() + " to " + player1.getScore()); } else { System.out.print("It's a tie " + player2.getScore() + " to " + player1.getScore()); }

Java Syntax – Control Structures - Conditional Switch statements handle multiple cases switch (ch) { case 'A': doSomething(); // Triggered if ch == 'A' break; case 'B': case 'C': doSomethingElse(); // Triggered if ch == 'B' or ch == 'C' break; default: doSomethingDifferent(); // Triggered in any other case break; }

Java Syntax – Arrays Arrays are an ordered collection  A dozen eggs  The passengers on an airplane // one dimensional array int[] numbers = new int[5]; numbers[0] = 2; numbers[1] = 5; int x = numbers[0]; // multi dimensional array int[][] numbers = new int[3][3]; number[1][2] = 2;