1. Example: Card Game Create a class called “Card”
Has thirteen static variables for the possible values of a playing card
Has four static variables, one for each suit
Has two instance attributes: value and suit
Create a class called “Deck”
Has an array of 52 cards
Initialize the deck to one card of each value and of each suit
Write a main function that plays “war”:
Draw two cards from a deck and compare their value to see which one wins

2. Re-using Code Recall the purpose of classes and objects
Model the real-world
Encapsulate the attributes and behaviors of concepts
Writing classes in a “black-box” fashion allows programmers to share and re- use code for many purposes!
Now that we have Card and Deck, we can use them for basically any card game that uses a standard deck of cards
The game logic will be different, but in some driver class!
This (huge) benefit of object-oriented programming is what motivates the maintenance of the open source software libraries

3. Graphical Programming
(Obviously) hugely important development in history of computers
Allow much more logical and accessible presentation and manipulation of data
Requires much different programming and problem-solving techniques
Program efficiency becomes much more important
Many more approaches to similar problems
Much more hardware dependent

4. Graphics Basics
A screen is broken down into small light-emitting diodes, forming “pixels”
To display an image or text, the right ones need to be lit up or turned off
For colors, there are three different hues of pixels that are adjusted to different intensities

5. Screen layout
Screens are rendered using an x-y axis, where the origin is in the top- left
Similar to how text-only terminals operated (see the terminal in Eclipse)
Java will abstract away many of the finer details, giving more logical access to the viewport of your program
The OS will also take care of placement, dragging, etc. of your graphics window

6. Getting starting with Graphics
No user-interaction (buttons, text input, etc.) yet
Only “output” graphics: shapes and text
Requires some initial setup to prepare the graphics and window
Starter file with comments: ava
Download and change the three occurrences of “SimpleAnimationStarter” to whatever class name you need

7. Creating a graphic
Similar to the Scanner, we will get an graphics context from Java:
Graphics g;
The Graphics class has many methods that let us choose to display primitive graphical elements:
Text rendering
Rectangles
Circles
Full list:

8. Drawing Lines
If we want to draw a line, we need to specify its end points
Two points in 2d – four coodinates
E.g.
g.drawLine(xOne, yOne, xTwo, yTwo);
We can loop it, and orient the lines any way we want!

9. Drawing rectangles g.drawRect(int x, int y, int width, int height)
Draws the outline of a rectangle with top-left at (x,y) and width x height dimensions
g.fillRect(…)
Fills the rectangle with the current color
We can change color with
g.setColor(Color c)
We can access different color constants like Color.BLUE, Color.GREEN, Color.RED, etc.

10. Drawing circles and ovals
g.fillOval(int x, int y, int height, int width)
Same idea as rectangle, but coodinates are the corner of the bounding rectangle
Can also use g.drawOval(…)

11. Examples: Draw a set of lines on the screen
Draw a set of nested rectangles
Make the nested rectangles animated to move “inward”
Draw random circles
Draw a moving circle

12. Animate Objects Create a class called “Circle”
centerX and centerY coordinates
Radius size
velocityX and velocityY
Make one circle starting somewhere random, and update its position every frame, based on the velocity