Notes for Tue and Thu (helping with these two assignments) also posted.

Tonight the notes will be augmented with even more specific steps, to be posted Tue morning.

Thanks to Adam Mendelevitz for bringing up regular expressions tonight during office hours:

import java.util.regex.*;
import java.util.*; 

public class One {
  public static void main( String args[] ){
    Scanner s = new Scanner(System.in); 
    String line; 

    Pattern circleMatch = Pattern.compile( "Circle radius ([0123456789]+) location (-{0,1}\\d+) (-{0,1}\\d+)" );

    Pattern rectangleMatch = Pattern.compile( "Rectangle size (\\d+) (\\d+) location (-{0,1}\\d+) (-{0,1}\\d+)" );

    System.out.print("Enter>"); 
    while (s.hasNextLine()) {
      line = s.nextLine(); 
      if (line.equals("done")) break;
      System.out.println(line); 
      Matcher circle = circleMatch.matcher( line );
      Matcher rectangle = rectangleMatch.matcher( line );
      if (circle.find()) {
        System.out.println("I see a Circle, radius " + 
                           circle.group(1) + " at (" + circle.group(2) + ", " + circle.group(3) + ")"); 
      } else if (rectangle.find()) {
        System.out.println("I see a Rectangle."); 
      } else { 
        System.out.println("I don't see what you're saying."); 
      } 
      System.out.print("Enter>"); 
    }     
  }
}

-bash-3.2$ java One
Enter>Circle radius 2 location 1 2
Circle radius 2 location 1 2
I see a Circle, radius 2 at (1, 2)
Enter>Rectangle size -1 3 location 2 10
Rectangle size -1 3 location 2 10
I don't see what you're saying.
Enter>Rectangle 12 4 location -1 -2
Rectangle 12 4 location -1 -2
I don't see what you're saying.
Enter>Circle radius 12 location -1 -1
Circle radius 12 location -1 -1
I see a Circle, radius 12 at (-1, -1)
Enter>done
-bash-3.2$ 

But that's easy to fix and the code above easily handles the text interface in Homework 3 problem 2.

import java.util.*; 

abstract class Shape implements Comparable<Shape> {
  abstract double area(); 
  public int compareTo(Shape other) {
    if (this.area() > other.area()) return 1; 
    if (this.area() < other.area()) return -1;
    else return 0; 
  } 
}

class Circle extends Shape {
  double area() { return 3.4; } 
  public String toString() { return "Circle area: " + this.area(); }
}

class Rectangle extends Shape {
  double area() { return 2.7; } 
  public String toString() { return "Rectangle area: " + this.area(); } 
}

class One {
  public static void main(String[] args) {
    ArrayList<Shape> a = new ArrayList<Shape>(); 
    a.add(new Circle()); 
    a.add(new Rectangle()); 
    a.add(new Circle()); 
    a.add(new Rectangle()); 
    System.out.println(a); 
    Collections.sort(a); 
    System.out.println(a); 
  } 
}

import java.util.*; 

class Four {
  public static void main(String[] args) {
    int[] a = new int[args.length]; 
    for (int i = 0; i < args.length; i++) 
      a[i] = Integer.parseInt(args[i]); 
    System.out.println(Arrays.toString(a)); 
    Arrays.sort(a); 
    System.out.println(Arrays.toString(a)); 
  }  
}

import java.util.*;

class Five {
  public static void main(String[] args) {
    ArrayList a = new ArrayList<Student>(); 
    a.add(new Student("Angie"   , 3.1)); 
    a.add(new Student("Amy"   , 3.1)); 
    a.add(new Student("Leslie", 3.4)); 
    a.add(new Student("Matt"  , 2.3)); 
    a.add(new Student("John"  , 1.7)); 
    a.add(new Student("Jamie" , 2.7)); 
    System.out.println(a);     
    Collections.sort(a); 
    System.out.println(a);     
  } 
} 

class Student implements Comparable<Student> {
  String name; 
  double gpa; 
  Student(String name, double gpa) {
    this.gpa = gpa; 
    this.name = name; 
  } 
  public String toString() {
    return this.name + ": " + this.gpa;
  } 
  public int compareTo(Student other) {
    if (this.gpa  > other.gpa) return  1;
    if (this.gpa  < other.gpa) return -1;
    else return this.name.compareTo(other.name);
  }

}

The text (as you know) can be found here:

Java All-In-One Desk Reference For Dummies, 2nd Edition 	
by Doug Lowe and Barry Burd 
John Wiley & Sons © 2007 (914 pages) 
ISBN:9780470124512

Alternatively you can search (in the same online collection):

Chapter 5 - Working with Collections

Herb Schildt's Java Programming Cookbook

Thiago	Rachel*
Alea*	Victor
Ron	Danielle*
Anthony*	Kurt
Adam*	Michelle
Brendan	Will*
Allen	Munir*
Jared	Daniel*

Problem is: implement a class of objects called Game that asks addition questions of you.

A Game object knows the player's name, grades the player's answer and keeps track of the score.

Here's how one can use such a class:

class Example {
  public static void main(String[] args) {
    Game a, b, c, d; 
    a = new Game("Adrian"); 
    a.report(); 
    a.ask(); 
    a.report();
    b = new Game("Alea"); 
    b.report(); 
    b.ask(); 
    b.report(); 
    a.ask(); 
    a.report();
    a.reset(); 
    a.report(); 
    
  } 
}

C:\Users\dgerman\Desktop>java Example
Game for Adrian created.
Adrian you have 0 correct answers out of 0 so far.
Adrian, what is 30 + 39? 69
That's right.
Adrian you have 1 correct answers out of 1 so far.
Game for Alea created.
Alea you have 0 correct answers out of 0 so far.
Alea, what is -10 + 49? 23
No, the right answer was: 39
Alea you have 0 correct answers out of 1 so far.
Adrian, what is 9 + 1? 10
That's right.
Adrian you have 2 correct answers out of 2 so far.
Game for Adrian has been reset now.
Adrian you have 0 correct answers out of 0 so far.

C:\Users\dgerman\Desktop>

Solution goes through this stages:

class Game {
  String name;
  Game(String name) {
     this.name = name; 
     System.out.println("Game for " + this.name + " has been created."); 
  }
  void ask() {
    System.out.println("I am Game method ask in " + this.name + "'s game/object"); 
  }
  void reset() {
    System.out.println("I am Game method reset in " + this.name + "'s game/object");     
  }
  void report() {
    System.out.println("I am Game method report in " + this.name + "'s game/object");     
  }
}

class Exercise {
  public static void main(String[] args) {
    Game a, b, c, d; 
    a = new Game("Adrian"); 
    a.report(); 
    a.ask(); 
    a.report();
    b = new Game("Alea"); 
    b.report(); 
    b.ask(); 
    b.report(); 
    a.ask(); 
    a.report();
    a.reset(); 
    a.report(); 
  } 
}

import java.util.*; 

class Game {
  int right, wrong, n1, n2;
  Scanner sc;  
  String name; 
  Game(String name) {
    this.name = name; 
    this.sc = new Scanner(System.in); 
    System.out.println("Game for " + this.name + " created."); 
  } 
  void ask() {
    this.n1 = (int) (Math.random() * 100 - 50); 
    this.n2 = (int) (Math.random() * 100 - 50); 
    System.out.print(this.name + ", what is " + this.n1 + " + " + this.n2 + "? ");
    int answer = this.sc.nextInt(); 
    if (answer == this.n1 + this.n2) {
      System.out.println("That's right."); 
      this.right += 1; 
    } else {
      System.out.println("No, the right answer was: " + (n1 + n2)); 
      this.wrong += 1; 
    } 
  } 
  void report() {
    System.out.println(this.name + " you have " + this.right + " correct answers out of " + (this.right + this.wrong) + " so far."); 
  } 
  void reset() {
    this.wrong = 0; 
    this.right = 0;
    System.out.println("Game for " + this.name + " has been reset now."); 
  } 
}

His copies of the programs you worked out then:

• Point
• Line
• Triangle
• Clock
• Elevator
• Player

Solutions for: Homework One, Homework Two.

Some warm-up quizzes for the introductory track:

1. Batch One
2. Batch Two
3. Batch Three
4. Batch Four
5. Batch Five
6. Batch Six
7. Batch Seven (try this if you think you know for loops)
8. Batch Eight
9. Batch Nine
10. Batch Ten

11. An older exam

class Point{

  int x, y; 

  public Point(int x, int y) {
    this.x = x;
    this.y = y;
  }

  public static double distanceBetween(Point a, Point b) {
    double distance; 
    distance = (a.x - b.x)*(a.x - b.x) + (a.y - b.y)*(a.y - b.y);
    return Math.sqrt(distance); 
  }

  public double distanceTo(Point a) {
    double distance, dx, dy; 
    dx = this.x - a.x; 
    dy = this.y - a.y; 
    distance = Math.sqrt(dx * dx + dy * dy); 
    return distance;
    
  }

  public static void main(String[] args){
    Point obama = new Point(0, 5);
    Point mccain = new Point(3, 8);
    System.out.println(obama.distanceTo(mccain));
    System.out.println(mccain.distanceTo(obama));
    System.out.println(Point.distanceBetween(obama, mccain));
  }
    

}

Script we used to interactively write this in class step by step.

Date: Thu, 29 Oct 2009 08:43:09 -0400 (EDT)
From: Adrian German 
To: ...
Subject: reading assignment


If you're reading this you're in A290/A590 Java or A202/A598 and you will
be studying Java over the next six weeks, or you are in A348/A548 and you
will also need to review Java over the same interval of time.

http://www.cs.indiana.edu/~dgerman/fall2009/students.html contains links
to all the student blogs, for feedback. The list has been updated today.

Office hour appointments can be scheduled here (list of available times is
updated weekly) http://silo.cs.indiana.edu:8346/cgi-bin/fall2009/schedule

http://www.libraries.iub.edu/scripts/countResources.php?resourceId=59555
has the book we will use as a reference: it's called Java for Dummies (no
offense) 9 books in 1 by Lowe and Burd.

For this week please look through Book I and II.

http://www.cs.indiana.edu/classes/a202-dger/sum2009/code/0727.html has the
code examples in the book. We're going to go through these in class today.

Please let me know if you have questions and/or if you need any help.

I will write a bit more in the evening.

Sincerely,
Adrian German

--

Today's lecture will discuss object oriented programming.

We start with a collection of examples in Python, Javscript and Java.

You can refer to

http://www.libraries.iub.edu/scripts/countResources.php?resourceId=59555

Also a book by Thomas Petchel, the last three weeks of this class.

-bash-3.2$ ls -l
total 40
-rw-r--r-- 1 dgerman faculty  720 Oct 22 11:41 template.py
-rw-r--r-- 1 dgerman faculty 2469 Oct 22 11:46 client.py
-rwx------ 1 dgerman faculty  152 Oct 22 13:16 one
-bash-3.2$

Call one and it will drive on land. It will work.

Now here is the "boat":

-bash-3.2$ ls -l
total 40
-rw-r--r-- 1 dgerman faculty  720 Oct 22 11:41 template.py
-rw-r--r-- 1 dgerman faculty 2469 Oct 22 11:46 client.py
-rwx------ 1 dgerman faculty  152 Oct 22 13:16 one
-rw-r--r-- 1 dgerman faculty 1795 Oct 22 13:35 server.py
-rwx------ 1 dgerman faculty   75 Oct 22 13:17 two
-bash-3.2$ 

If

• one is the driver
• that drives the client.One car
• that has the template.Engine engine,

• then two is the driver that drives the server extension of the client car.

server is only adding the propellers to the car.

In server the wheels are not used. (We expected that, we knew that).

But

• inside server (which is small and focused, not like a whole new program written from scratch)
• there is an entire car working like a normal car but with the controls controlling the wheels redirected to the "propellers".

Also copy two and make it executable.

two works with the database and provides the server side version of one.

Just make sure that there are non references to my username, port, server in the file. Mine can be accessed from here:

http://silo.cs.indiana.edu:8346/cgi-bin/1022/two

mysql> select * from hwFive;
+------------+---------------------------------+------+------+------+------+---------------------+
| session_id | message                         | n1   | n2   | m1   | m2   | modified            |
+------------+---------------------------------+------+------+------+------+---------------------+
| 58974425   | Very good.Score now: 2 out of 4 |   26 |   23 |    2 |    4 | 2009-10-22 13:36:24 | 
| 11848907   | Welcome                         |   17 |  -18 |    0 |    0 | 2009-10-22 13:36:42 | 
| 24997385   | Very good.Score now: 1 out of 1 |  -37 |   48 |    1 |    1 | 2009-10-22 13:37:40 | 
+------------+---------------------------------+------+------+------+------+---------------------+
3 rows in set (0.00 sec)

mysql> 

1. Go to (create it if necessary) ~/apache/cgi-bin/1022
2. Copy in that folder template.py
3. Now copy client.py into the same folder.
4. Finally copy one make it executable and access it from the web.
5. To access use URL http://silo.cs.indiana.edu:xxxx/cgi-bin/yyyy/one

Now let's go to MySQL:

cd /nobackup/dgerman/mysql-5.0.22/

-bash-3.2$ ls -ld connect_as_lbird 
-rwx------ 1 dgerman faculty 105 Oct 13 12:26 connect_as_lbird

-bash-3.2$ cat connect_as_lbird 
mysql --socket=/nobackup/dgerman/mysql/mysql.sock \
  --port=8974 --host=silo.cs.indiana.edu -u lbird -p
-bash-3.2$ 

-bash-3.2$ ./connect_as_lbird 
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.0.22-log

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql>

use awards;

create table hwFive (
  session_id char(8) primary key,
  message varchar(240),
  n1 int,
  n2 int,
  m1 int,
  m2 int,
  modified   timestamp
);

Notes wrote in class today: here.

Notes that help with Homework Five: here.

Some other notes:

• http://www.cs.indiana.edu/classes/a290-web/spr2008/tue0212.txt
• http://www.cs.indiana.edu/classes/a348/spr2008/thu0214-setup.txt
• http://www.cs.indiana.edu/classes/a348/spr2008/thu0214.txt
• http://www.cs.indiana.edu/classes/a348/fall2005/notes/labSix.html

Notes to be used in lab this week: or here.

Notes distributed in class today.

Additional notes for help with Homework Two (Friday pm notes).

Here's what we worked in lab today: notes.

Lecture notes for today can be found here.

Here's how the lab today might go (notes from a similar exercise yesterday).

Transcript of notes from class today.

Links distributed in class on Tuesday are here.

Last semester's A201 website remains available to you.