Lab 6: Shapes & Picture Extended Ellipse & Rectangle Classes Stand-Alone GUI Applications

Agenda Create more shape classes –Ellipse –Rectangle Change applet to stand alone GUI application Created by Emily Hill & Jerry Alan Fails

Graphical Applications Except for the applets seen in Chapter 2, the example programs we've explored thus far have been text-based They are called command-line applications, which interact with the user using simple text prompts Let's examine some Java applications that have graphical components These components will serve as a foundation to programs that have true graphical user interfaces (GUIs) Copyright © 2012 Pearson Education, Inc.

GUI Components A GUI component is an object that represents a screen element such as a button or a text field GUI-related classes are defined primarily in the java.awt and the javax.swing packages The Abstract Windowing Toolkit (AWT) was the original Java GUI package The Swing package provides additional and more versatile components Both packages are needed to create a Java GUI- based program Copyright © 2012 Pearson Education, Inc.

GUI Containers A GUI container is a component that is used to hold and organize other components A frame –Container displayed as a separate window with a title bar –Can be repositioned and resized on the screen as needed A panel –Container that cannot be displayed on its own but is used to organize other components –Must be added to another container (like a frame or another panel) to be displayed Copyright © 2012 Pearson Education, Inc.

GUI Containers A GUI container can be classified as either heavyweight or lightweight A heavyweight container is one that is managed by the underlying operating system (e.g. a frame) A lightweight container is managed by the Java program itself (e.g. a panel) Copyright © 2012 Pearson Education, Inc.

Convert Picture from Applet to Stand-Alone GUI Download and import the Picture.Extended starter code from the Course Materials of Canvas. –Rename the project to PictureExtended_netID –You can copy pieces from your previous CircleApplet or Picture project to PictureApp_netid Create a copy of the Picture class –Call one PictureApp, the other PictureApplet Change Picture class –Change so it extends JPanel not JApplet –Change init method to be a default constructor –Change paint method name to paintComponent –Add a main method (see General Template on next slide) Created by Emily Hill & Jerry Alan Fails

General Template for Stand-Alone GUI public static void main(String[] args) { JFrame frame = new JFrame(”Picture Test"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JPanel panel = new PictureApp(); panel.setPreferredSize(new Dimension(500,500)); frame.getContentPane().add(panel); frame.pack(); frame.setVisible(true); } Created by Emily Hill & Jerry Alan Fails

Create Rectangle and Ellipse Classes Create a Rectangle and an Ellipse class with: –Create fields for x & y positions, width, height, fillColor, and outlineColor –Create default constructor & constructor with parameters –Add getter & setter methods –Add a paintComponent method –Add get area & get perimeter methods Area of ellipse: Perimeter (circumference) of ellipse: Add rectangle and ellipse objects to your picture (to test your new classes) Created by Emily Hill & Jerry Alan Fails

Circle getArea public double getArea() { return Math.PI * radius * radius; } Don’t forget to test your getArea & getPerimeter methods in a main inside each shape class Created by Emily Hill & Jerry Alan Fails

Recap Created more classes –Ellipse & Rectangle –Just specified: fields, constructors, methods Change applet to stand alone GUI application –Note didn’t have to change Circle, Square, Ellipse, Rectangle, just a few changes to Picture Also briefly mentioned type promotion –Math.pow(double, double) can receive integer values because no information is lost e.g. Math.pow(3, 4) Created by Emily Hill & Jerry Alan Fails

Homework Finish lab exercise –Next lab: we will use these classes to create other classes Read Chapter 4 CodingBat Created by Emily Hill & Jerry Alan Fails