Intro to Java 2 By Geb Thomas Based on the Java TutorialJava Tutorial

What is Java? Platform independent code Runs on many machines Runs within browsers as applets Will soon run on cell phones, microwaves, car displays and washing machines, for example.

How do you make Java go? Create a java file (HelloWorldApp.java) Compile the java file with javac to make bytecodes (javac HelloWorldApp.java) Creates HelloWorldApp.class Run the bytecodes on a java virtual machine. (java HelloWorldApp)

Where Do You Get This Stuff?

A Simple Example /* * The HelloWorldApp class implements an application that * simply displays "Hello World!" to the standard output. */ class HelloWorldApp { public static void main(String[] args) { System.out.println("Hello World!"); //Display the string. }

Objects Objects are high level concepts that can have Variables (data associated with the concept) Methods (actions associated with the concept)

Passing Messages

Classes Definition: A class is a blueprint, or prototype, that defines the variables and the methods common to all objects of a certain kind.

Inheritance Subclass Superclass Hierarchy Inheritance Override Abstract classes

Putting the Ideas Into Action ClickMe.java Spot.java

First Swing Example import javax.swing.*; public class HelloWorldSwing { public static void main(String[] args) { JFrame frame = new JFrame("HelloWorldSwing"); final JLabel label = new JLabel("Hello World"); frame.getContentPane().add(label); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.pack(); frame.setVisible(true); }

Actions and Events Examples of Events and Their Associated Event Listeners Act that Results in the EventListener Type User clicks a button, presses Return while typing in a text field, or chooses a menu item ActionListener User closes a frame (main window) WindowListener User presses a mouse button while the cursor is over a component MouseListener User moves the mouse over a component MouseMotionListen er Component becomes visible ComponentListener Component gets the keyboard focus FocusListener Table or list selection changes ListSelectionListene r