Upload
julie-sanders
View
215
Download
0
Embed Size (px)
Citation preview
Intro to Java 2
By Geb ThomasBased on the Java Tutorial
What is Java?Platform independent codeRuns on many machinesRuns within browsers as appletsWill 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?
http://java.sun.com
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
ClassesDefinition: A class is a blueprint, or prototype, that defines the variables and the methods common to all objects of a certain kind.
InheritanceSubclassSuperclassHierarchyInheritanceOverrideAbstract classes
Putting the Ideas Into Action
ClickMe.java Spot.java <applet code="ClickMe.class" width="300" height="150"> </applet>
First Swing Exampleimport 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 Event Listener 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 MouseMotionListener Component becomes visible ComponentListener Component gets the keyboard focus FocusListener
Table or list selection changes ListSelectionListener