// APS101, Winter 2009: Lecture 6 (Jan. 20)
//
// Review: so far, we've worked with objects in the Interactions pane.
// Examples of classes we've seen: Date, String, Integer, Double, JFrame.
JFrame j;
import javax.swing.JFrame;
JFrame j;
j = new JFrame();
j.setVisible(true)
j.setSize(400, 400)
j.setVisible(false)
j.setVisible(true)
j.setTitle("This is my window!")
j.getWidth()
j.getHeight()
j.getTitle()
// Today, you'll be learning how to write your own programs. 
// Specifically, you'll learn how to write your own classes.
// First, let's look at some terminology...
//
// What is a class?
// A class is a blueprint that specifies what an
// object of that class is supposed to look like.
// (i.e., what variables and methods it's supposed to have.)
//
//
// instruction: action to be performed
// Java statement: an instruction written in the Java language
// Java program: an organized collection of Java statements
// execute: follow the instructions
//
//
// There are three types of methods:
// function: returns data of a particular type
// procedure: perform a set of actions, but don't return any data
// constructor: functions that create the object and return it
// ex. of a procedure: setSize, setTitle, etc.
// ex. of a function: charAt, getTitle, etc.
//
// What if we want to customize the JFrame class?
// (we wrote OurJFrame.java)
//
//
// NOTES
//
// We start off with a file called MyFileName.java,
// and put all our code in there.
//
// Then, we compile it, and get MyFileName.class.
// Be careful: DrJava makes backups of .java files,
// in the form of .java~ (don't open or work with these!)
//
// What is "this"?
// "this" refers to the current object.
// so, inside a class, you should always put "this" in front
// of instance variables and methods. 
// ex. this.variableName and this.methodName()
//
// Arguments vs. Parameters
// parameter: an abstract definition of what the input
// to a method is supposed to be (what TYPE!).
// argument: the actual value of the input that is 
// given to the method.
// ex. String title (param) vs. "This is OUR frame!" (arg)
//
// Let's try out the new class we wrote!
OurJFrame ow = new OurJFrame("This is OUR frame!"); 
ow.doubleWidth()
ow.getOurTitle()