Monday, December 17, 2012

import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)
import java.awt.Color;

/**
 * A simple counter with graphical representation as an actor on screen.
 * 
 * @author mik
 * @version 1.0
 */
public class Counter extends Actor
{
    private static final Color transparent = new Color(0,0,0,0);
    private GreenfootImage background;
    private int value;
    private int target;

    /**
     * Create a new counter, initialised to 0.
     */
    public Counter()
    {
        background = getImage();  // get image from class
        value = 0;
        target = 0;
        updateImage();
    }
    
    /**
     * Animate the display to count up (or down) to the current target value.
     */
    public void act() 
    {
        if (value < target) {
            value++;
            updateImage();
        }
        else if (value > target) {
            value--;
            updateImage();
        }
    }

    /**
     * Add a new score to the current counter value.
     */
    public void add(int score)
    {
        target += score;
    }

    /**
     * Return the current counter value.
     */
    public int getValue()
    {
        return value;
    }

    /**
     * Set a new counter value.
     */
    public void setValue(int newValue)
    {
        target = newValue;
        value = newValue;
        updateImage();
    }

    /**
     * Update the image on screen to show the current value.
     */
    private void updateImage()
    {
        GreenfootImage image = new GreenfootImage(background);
        GreenfootImage text = new GreenfootImage("" + value, 22, Color.BLACK, transparent);
        image.drawImage(text, (image.getWidth()-text.getWidth())/2, 
                        (image.getHeight()-text.getHeight())/2);
        setImage(image);
    }
}

Monday, December 10, 2012

Begin Greenfoot Game

Before we begin, check to see if Greenfoot is still installed on your station. If not, follow the previous instruction and install it. Then we will resume our basic game creation.

We will again be accessing the Joy of Code video tutorials for Greenfoot: http://blogs.kent.ac.uk/mik/category/joy-of-code/page/2/

Last week we used tutorial #4 to begin "Trick the Turtle". Basically we were able to add "instances" of the turtles to our "world" and have them behave as we programmed them to.

This week we will be continuing with the Trick the Turtle project using tutorial #5 (in Clearlake) and tutorial #6 (in both Clearlake and Lakeport). These two tutorials will add "If Statements" and "Random Behavior" to our game.

Time permitting we will also work through tutorial #7 to give the turtles some food, and then on to tutorial #8 to do some basic housekeeping and clean up our code.

Monday, November 26, 2012

Assignment: Teacher Contact

Assignment: Send me an email (rgriffith@kusd.lake.k12.ca.us) and answer the following questions:

What would you need to see for you to call this Java Class "successful" at the end of the year?
What would you like to get out of it?
What are you willing to put into it?

Thanks!

Warm-Up: Getting Back to Java!

What I would like you to do as a warm-up activity is to comment, format and improve this game. Be creative:

import java.util.Scanner;
public class OOPExample1 {
public static void main(String[] args) {
CPU cpu1 = new CPU();
Scanner sc1 = new Scanner(System.in);
boolean validmove = false;
String userMove = "";
while(!validmove){
System.out.println("Input your move (rock, paper or scissors): ");
userMove = sc1.nextLine();
userMove = userMove.toLowerCase();
if(userMove.equals("rock") || userMove.equals("paper")
||userMove.equals("scissors")){
validmove = true;
}
}
String CPUMove = cpu1.getCPUMove();
cpu1.comparemoves(CPUMove, userMove);
}
}
class CPU{
public void comparemoves(String CPUMove, String userMove){
if(userMove.equals("rock")){
if(CPUMove.equals("rock")){
outputmoves("rock", "Tie!");
}
if(CPUMove.equals("paper")){
outputmoves("paper", "I win!");
}
if(CPUMove.equals("scissors")){
outputmoves("scissors", "You win!");
}
}
if(userMove.equals("paper")){
if(CPUMove.equals("rock")){
outputmoves("rock", "You win!");
}
if(CPUMove.equals("paper")){
outputmoves("paper", "Tie!");
}
if(CPUMove.equals("scissors")){
outputmoves("scissors", "I win!");
}
}
if(userMove.equals("scissors")){
if(CPUMove.equals("rock")){
outputmoves("rock", "I win!");
}
if(CPUMove.equals("paper")){
outputmoves("paper", "You win!");
}
if(CPUMove.equals("Scissors")){
outputmoves("scissors", "Tie!");
}
}
}
public void outputmoves(String cpuout, String status){
String output = "I played ".concat(cpuout).concat(".").concat(status);
System.out.println(output);
}
public String getCPUMove(){
int choice = (int) Math.floor(Math.random()*3);
String rpsmove = "";
switch(choice){
case 0: rpsmove = "rock"; break;
case 1: rpsmove = "paper"; break;
default: rpsmove = "scissors"; break;
}
return rpsmove;
}
}

The New Boston video tutorials for Java

http://thenewboston.org/list.php?cat=31

Java

87 Videos

Monday, November 5, 2012

Beginning GridWorld

This week we will begin working through the GridWorld Case Study in the Java Methods book (pp.43-78). I have also created a packet (GridWorld AP Computer Science Case Study Student Manual) to use during this process.

To begin with, we'll need to download the source code (see previous post), unzip the file, and drag the GridWorldCode folder to the main Java folder. Then we'll add the GridWorld.jar file to the BlueJ library. Once that is complete we will be able to view and run the BugRunner program.

Read 3.1 Prologue: Consider how huge a computer program needs to be to do something like have a soldier run through a battlefield. Not only is the battlefield an object... and the soldier is an object... and the soldiers head is an object... and his eye is an object (if it has its' own properties)... but going deep enough, the pupil in the soldiers eye could be an object that dilates or contracts. As projects grow like this you will need to learn techniques to keep things organized.

Read 3.2 Case Study: GridWorld: The text describes the difference of class and objects again. And in the section where they describe the difference between the visual representation of objects and the coded objects themselves, you can think of programs like Minecraft where you can apply a different "skin" to an object. The program works exactly the same, but the skin is different. This is also the section where they have you read through Part 1 of the Student Manual (which I am providing you).

This section also discusses the important function of CRC cards for classes. In this example you can see two different classes (Predator and Habitat), the class "responsibilities" (generally what it does), and "collaborators" (other classes it depends on).

We will also be opening the BugRunner program and playing with the display.

Sunday, November 4, 2012

Bring Both Books This Week

Hey, folks. Let's go ahead and bring both Java books this week -- the BlueJ book and the big Methods book. We're going to explore some more of the clock program and begin looking at the Grid World project.

As we approach the GridWorld project we can find the necessary files at the CollegeBoard web site.

Thursday, November 1, 2012

Coin Toss Example

While this isn't the way we would probably have approached the coin toss project, this one is interesting because it tallies up the number of heads and tails we get out of 100 coin flips. This code involves using a counter, a Math.random number generator (0 or 1 is the result), a counter for the results of each of the sides of the coin, and a "do while" loop. Study the code and see if you can figure out what the unfamiliar code pieces are doing.


class Toss {
        public final int HEADS = 0;
        static int countH = 0;
        static int countT = 0;
        static int counter = 0;
        private static int face;

        public static void flip() {
                face = (int) (Math.random() * 2);
        }

        public String toString() {
                String faceName;
                counter++;
                if (face == HEADS) {
                        faceName = "Heads";
                        countH++;
                } else {
                        faceName = "Tails";
                        countT++;
                }
                return faceName;
        }

        public static void main(String[] args) {
                System.out.println("Outcomes:");
                do {
                        flip();
                        System.out.println(new Toss().toString());
                } while (counter < 100);
                System.out.println("Number of Tails: " + countT);
                System.out.println("Number of Heads: " + countH);
        }
}

Monday, October 29, 2012

Guess the Letter


// Guess the letter
class GuessLetter {
public static void main(String args[])
throws java.io.IOException {
char ch, answer = 'K';
System.out.println("I'm thinking of a letter between A and Z.");
System.out.print("Can you guess it: ");
ch = (char) System.in.read(); // get a char
if(ch == answer) System.out.println("** Right **");
else System.out.println("...Sorry, you're wrong.");
}
}

Boolean Numbers


// Demonstrate boolean values.
    class BoolDemo {
        public static void main(String args[]) {
            boolean b;
            b = false;
            System.out.println("b is " + b);
            b = true;
            System.out.println("b is " + b);
            // a boolean value can control the if statement
            if(b) System.out.println("This is executed.");
            b = false;
            if(b) System.out.println("This is not executed.");
            // outcome of a relational operator is a boolean value
            System.out.println("10 > 9 is " + (15 > 9));
    }
}

Characters


// Character variables can be handled like integers.
class CharArithDemo {
public static void main(String args[]) {
char ch;
ch = 'X';
System.out.println("ch contains " + ch);
ch++; // increment ch
System.out.println("ch is now " + ch);
ch = 90; // give ch the value Z
System.out.println("ch is now " + ch);
}
}

Working With Strings

Tonight we will be working with strings making a Haiku -- and, as usual, your homework will involve utilizing what you learn tonight. :)


//Mad Libs Haiku

import java.util.Scanner;

public class Haiku
{
   public static void main( String[] args )
   {
   //create Scanner to get input from user
      Scanner input = new Scanner( System.in );

      String word1;//Person's name, 2 syllables
      String word2;//Noun, 2 syllables
      String word3;//Adjective, 1 syllable
      String word4;//Adjective, 1 syllables
      String word5;//Adjective, 2 syllables

      System.out.print( "Type a person's name -- two syllables: " );//prompt
      word1 = input.nextLine();//read user input

      System.out.print( "Type a two-syllable noun: " );//prompt
      word2 = input.nextLine();//read user input

      System.out.print( "Type a one-syllable adjective: " );//prompt
      word3 = input.nextLine();//read user input

      System.out.print( "Gimme another one-syllable adjective: " );//prompt
      word4 = input.nextLine();//read user input

      System.out.print( "Last one! A two-syllable adjective: " );//prompt
      word5 = input.nextLine();//read user input


      System.out.println( "\n\nHere is your Mad Libs-style haiku:\n\n" );
      System.out.printf( "I said to %s,\n", word1 );
      System.out.printf( "\"My love is like a %s:\n", word2 );
      System.out.printf( "%s, %s, and %s.\"\n", word3, word4, word5 );

   }//end method main
}//end class Haiku

Sunday, October 28, 2012

Bring your blue "Objects First with Java" books...

Bring your blue "Objects First with Java" books to class on Monday/Tuesday. After we work through some more code examples and looking at the homework challenges, we're going to begin working on Chapter 3.

Friday, October 26, 2012

Homework Projects for Monday/Tuesday

I would like for you to create the following projects to bring in on Monday/Tuesday class:

Create a Class called CoinToss
Add appropriate comments, titles and attributions
Display a title "text graphic" when the program is executed
Ask the user to choose "heads or tails"
Generate a random number (using either of the methods that I showed you)
Display the going as a "text graphic" (either heads or tails)
Tell the user whether they win or lose

Create a simple menu program which allows users to run different routines:

Create a new Class
Add appropriate comments, titles and attributions
Display a title "text graphic" when the program is executed
Display a menu of at least 4 items
Have user input a menu choice (i.e. 1 - 4)
If the user did not enter a valid menu choice give them an error message and end program.
For each of the menu choices, do something different (i.e. one can generate a random horoscope, one can ask the user for two numbers to multiple, what can calculate the square feet in a room, etc.)

We will take some time to demo a few in class before we get started.

Fewest Coins Possible: The idea for this project is that we ask the user for the amount of change they have (let's assume it's $1 or less) and we figure out the fewest number of coins needed to total that amount. Now if you remember from the "Equally Divide" project we calculated a remainder as "Left Over" -- and this is similar to that. We will calculate the number of quarters needed, get the remainder, divide that by the number of dimes, etc.

♦ Set up variables for each coin type: Quarters, Dimes, Nickels, and Pennies
♦ Set up a variable for the currentCents
♦ Ask users to enter the amount of cents ($1 would be 100, for example)
♦ Calculate Quarters first, then find the remainder and set currentCents to the remainder amount
♦ Calculate Dimes from the remainder (again currentCents)
♦ Continue with Nickels and Pennies
♦ Display the results like, "Quarters: xx"
♦ Amounts to try: 91, 41, 59, 6 (and obviously others)

This program is definitely possible for you to complete knowing what you already know.

Saturday, October 20, 2012

This week we will be playing with some existing source code. We will discuss what the programs do, how they are outlined, and what we can do to improve them. Then we will attempt to expand on the programs.

CASE STUDY #1: Movie Tickets

Let's look at this code for a movie ticket program:

import java.util.Scanner; class TicketPrice { public static void main(String args[]) { Scanner myScanner = new Scanner(System.in); int age; double price = 0.00; System.out.print("How old are you? "); age = myScanner.nextInt(); if (age >= 12 && age < 65) { price = 9.25; } if (age < 12 || age >= 65) { price = 5.25; } System.out.print("Please pay $"); System.out.print(price); System.out.print(". "); System.out.println("Enjoy the show!"); } }

First of all, what is the name of this Class?
What are we bringing into the Class from Java that is already built for us?
What does "Scanner" do?
What does "double" mean in Java?
What variables are we using in this code? (I see three)
What are some of the things that are missing in this code?
What would the ticket price be for an 8 year old? A 14 year old? A 66 year old?
Draw a flow chart indicating the flow of this program.

Next, let's update the source code:

Begin by formatting the source code to be more readable -- add line breaks, indent (Tab) some of the lines, etc. (See the next case study for an idea of how to format it)
Add some comments to the code. Remember that every Class needs a title, author(s), and version (number or dates) and maybe some comments describing what a formula or function does.

CASE STUDY #2: Divide Equally

Next let's look at this strange code for a program that will divide the total number of gumballs equally among a varied number of children:

import java.util.Scanner; class EquallyDivide { public static void main(String args[]) { Scanner myScanner = new Scanner(System.in); int gumballs; int kids; int gumballsPerKid; System.out.print("How many gumballs? "); gumballs = myScanner.nextInt(); System.out.print("How many kids? "); kids = myScanner.nextInt(); gumballsPerKid = gumballs / kids; System.out.print("Each kid gets "); System.out.print(gumballsPerKid); System.out.println(" gumballs.");

} }

So let's work with this code:

Add some comments / labels.
What is the difference between:

System.out.println
System.out.print

With variable names like "gumballs" or "kids" or "gumballsPerKid", this program is pretty specific. What sorts of names could we use for variables to make this program usable for other purposes? The "gumballs" variable might be more useful as "items", for example. Remember, however, that you can change all instances of "gumballs" but "gumballsPerKid" is a completely different variable name.
Draw a flowchart indicating the flow of this program.
What code could we add to figure out how many gumballs are left over after they have been divided equally?

CASE STUDY #3: Magic Cue Ball

For case number 3 we have "The Magic CueBall" -- okay, so it's ripped off... but it works... sort of:

import java.util.Scanner; import java.util.Random; class MagicCueBall { public static void main(String args[]) { Scanner myScanner = new Scanner(System.in); Random myRandom = new Random(); int randomNumber; System.out.print("Type a Yes or No question: "); myScanner.nextLine(); randomNumber = myRandom.nextInt(10) + 1; if (randomNumber > 5) { System.out.println("Yes. Isn’t it obvious?"); } else { System.out.println("No, and don’t ask again."); } } }

Let's do some playing with the code again:

Again, begin by adding comments/labels to the code.
What Java utils are we bringing in this time?
When you run this program, how does the output text differ from the text written in the code?
Before the "if" statement, randomNumber can be what possible numbers? Why is there a +1 at the end of the line?
Add some variation to the possible responses:

4 different "Yes" answers
4 different "No" answers
2 different "Ask Again" answers

At the beginning of the program (before asking the user to type a yes or no question), add a title text graphic. For example:

*********************************
* Magic Cue Ball 1.0 ~ by Your Name *
*********************************

What else could we add to make this application more usable?

CASE STUDY #4: A Number Guessing Game -- Building a Program Step By Step

Course Textbooks

We have two textbooks for this Java Programming course:

Java Methods: Object-Oriented Programming and Data Structures (Second AP* Edition -- with GridWorld) by Maria Litvin and Gary Litvin. [ISBN: 978-0-9824775-7-1]
Objects First With Java: A Practical Introduction Using BlueJ (5th Edition) by David J. Barnes & Michael Kölling. [ISBN: 978-013-249266-9]
Barron's AP Computer Science A test prep guide (5th Edition) [ISBN: 978-0-7641-4373-1]

We will also be connecting to various resources on the web.

One recommended text which you can view can be found here.

I Teach History: Programming