Object-Oriented Software Engineering

Java with added Swing

22UniS

Contents

• Overview of Swing components

• Introduction to case study example

• Basic structure of Java Swing application

• Overview of runtime execution of application

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Swing Basics

Java provides a collection of Foundation classes to allow easy implementation of GUI-s (Graphical User Interface)

For this lecture borrowed heavily from:http://java.sun.com/docs/books/tutorial/information/

 Top-Level Containers

               

Applet

                                                

Dialog

                                 

Frame

44UniS

Swing Basics

General-Purpose Containers

                                    

Panel

                                       

Scroll pane

                                                   

Split pane

                                         

Tabbed pane

                        Tool bar

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Swing Basics

Special-Purpose Containers

                                              

Internal frame

                                                       

Layered pane

                                                               

Root pane

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Swing Basics

Basic Controls  

                       

Buttons

                               

Combo box

                   

List

                                     

Menu

                                            

Slider

       Spinner

                   Text field or Formatted text field

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Swing Basics

Uneditable Information Displays

                              

Label

                           

Progress bar

                               

Tool tip

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Swing Basics

Interactive Displays of Highly Formatted Information  

                                

Color chooser

                                                      

File chooser

                                         

Table

                   

Text

                      

Tree

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The JComponent Class

java.lang.Object java.awt.Component

java.awt.Container

javax.swing.JComponent

java.awt.Window

java.awt.Frame

javax.swing.JFrame

javax.swing.JLabel

javax.swing.JToolbar

javax.swing.JPopupMenu

javax.swing.JFileChooser

javax.swing.JTextArea

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Swing Basics: Course Case Study

JTextArea

JTextField

JToolBar

JPopupMenu

JFrame

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Swing Basics: Course Case Study

ImageIconJLabel

JFileChooser

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Swing Basics

To make any graphic program work we must be able to create windows and add content to them.

To make this happen we must:

• Import the pertinent packages.

• Set up a top-level container.

• Display the container.

• Be thread-safe.

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Swing Basics

• Import the pertinent packages.

import javax.swing.*;

• Set up a top-level container.

JFrame.setDefaultLookAndFeelDecorated(true); JFrame frame = new JFrame("HelloWorldSwing");

• Display the container.

frame.pack(); frame.setVisible(true);

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Swing Basics

• Be thread-safe.

public static void main(String[] args) {javax.swing.SwingUtilities.invokeLater( new Runnable() { public void run() { createAndShowGUI(); } } );};

Swing event-handling and painting code executes in a single thread, called the event-dispatching thread. invokeLater adds a new thread to be executed by the event dispatcher.

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Swing Basics: Hello World Example

JFrame JLabel

String used in constructor method for JLabel

Exit program on close

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import javax.swing.*; public class HelloWorldSwing {private static void createAndShowGUI() { JFrame.setDefaultLookAndFeelDecorated(true);

JFrame frame = new JFrame("HelloWorldSwing"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); String display_string = “Some Text”

JLabel label = new JLabel(display_string); frame.getContentPane().add(label);

//Display the window. frame.pack(); frame.setVisible(true); } public static void main(String[] args) { javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); }}); }}

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HelloWorldSwing

JLabel label = new JLabel(display_string);frame.getContentPane().add(label);

JLabel label = new JLabel(display_string);java.awt.Container frameCt = frame.getContentPane();frameCt.add(label);

Strange Part of Code

Is equivalent to these two lines

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Sequence Diagram for HelloWorldSwing:HelloWorldSwing :Event Dispatcher frame:JFrame

label:JLabelframeCt:Container

createAndShowGUI

<<creates>>

setDefaultCloseOperation

<<creates>>

getContentPane

add(label)

pack

setVisible(true)

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HelloWorldString Variable ScopeTrying to access variables declared inside createAndShowGUI outside of the definition is illegal.

E.g:public class HelloWorldSwing { ........ private static void createAndShowGUI() { ........

JFrame frame = new JFrame("HelloWorldSwing"); ........ } java.awt.Container ct = frame.getContentPane(); public static void main(String[] args) { javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); }}

$ javac HelloWorldSwing.javaHelloWorldSwing.java:29: cannot resolve symbolsymbol : variable framelocation: class HelloWorldSwing java.awt.Container ct = frame.getContentPane(); ^1 error

2020UniS

String Handling in HelloWorldSwing

static String display_string =

"<html><H1>Hello World<P>"+ "<H1>This is an example of a"+ " <font color=#ff0a0a>JFrame</font> Swing Object.<BR>"+ "A <font color=#ff0a0a>JFrame</font>"+ " by itself does not provide any "+ "functionality.<BR>"+ "Even the text in the content pane of this"+ " <font color=#ff0a0a>JFrame</font><BR>"+ "is constructed by a <font color=#ff0a0a>JLabel</font> object."+ "</html>";

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String Handling in HelloWorldSwing

String simpleString = "this" + "and" "that";

Is the same as:

String simpleString = "thisandthat";

To get spaces would write:

String simpleString = "this " + "and " + "that ";

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String Handling in HelloWorldSwing

Can add formatting such as new line `\n' and tabs `\t'

String simpleString = "\nNewLine\twith tabs"

Some swing components (such as JLabel) can interpret some HTML

String simpleString = "<html><H1>Hello World<P>";

Note this is not always true.

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