Session1 Module1 Intro to Swing

8/3/2019 Session1 Module1 Intro to Swing

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APJ-I, Session 1

Module 1: Introduction to SWING



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Objectives

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What is Swing?

• Java Foundation Classes (JFC)

is a graphical framework

which includes the older

Abstract Window Toolkit (AWT),

Swing and Java2D classes.• Swing supports a technology called

'Pluggable-Look-And-Feel' (PLAF)

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Abstract Window Toolkit (AWT) -1

• Abstract Window Toolkit (AWT) was the only libraryavailable to develop GUI based applications

• These components can be used to create a GUI basedstandalone application or applets

• The AWT components were based on peer-components

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Abstract Window Toolkit (AWT) -2

• The peer-component

dependency made the AWT

components heavy as memory

consumption and operational

performance was considered.• Hence, they were referred to

as heavy-weight components

•

AWT components would always have the 'look and feel' of the nativecomponents.

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Benefits of Swing over AWT

• Swing components are lightweight as compared to AWTcomponents.

• Swing components are visually appealing.• Swing components have more capabilities than AWT

components: – Buttons and Labels can display images – Borders drawn around most of the Swing components can be

changed. –

The behavior or appearance of a Swing component can bechanged – Swing components don't have to be rectangular – Swing is based on the Model-View-Controller Architecture

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MVC Architecture

• Model-View-Controller Architecture (MVC) decomposes the application intothree layers:

– The Model represents all the data and the various states of thecomponent

– The View depicts the graphical part on the screen. –

The Controller is responsible for determining whether the componentshould react to any input events from input devices such as thekeyboard or mouse.

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Separable Model Architecture

• Almost all modern user interface frameworks combine the View andController , whether they are based on SmallTalk, C++, or even JavaSwing.

• Swing packages each component's View and Controller into an objectcalled a User Interface (UI) delegate. For this reason Swing's underlying

architecture is more accurately referred to as Separable ModelArchitecture or theModel- Delegate Architecturerather than Model-View-Controller Architecture.

• Ideally communication between

both the Model and the UI Delegateis indirect, allowing more thanone Model to be associated withone UI Delegate, and vice versa.

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Overview of Container

• A Container is meant to contain components.

• There are two types of containers: top-level containers and general-purpose containers.

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The root pane -1

• The root pane has four parts Glass Pane, Layered Pane, Content Pane andMenu Bar.

• A glass pane is hidden by default.

• If the glass pane is made visible, then it's like a sheet of glass over all theother parts of the root pane.

•

It's completely transparent unless one implements the glass pane'spaintComponent () method so that it displays something.

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The root pane – Layered Pane

• Serves to position its contents, which consist of the Content Pane and theoptional Menu Bar. It can also hold other components in a specified z -order.

• Each root pane places its menu bar and content pane in an instance of JLayeredPane. The z - ordering that the layered pane provides enables

behavior such as displaying popup menus above other components.




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The root pane - Content Pane

• The Content Pane is the container of the root pane's visible components.Most GUI components are added to this content pane.

• The default content pane is a simple intermediate container that inheritsfrom JComponent, and uses a BorderLayout as its layout manager.

• The object-reference of the content pane of a top-level container is retrieved

by calling the getContentPane 0 method. You then add GUI components tothe content pane.




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The root pane - Menu Bar

•

All top-level containers can, in theory, have a menu bar. In practice,however, menu bars usually appear only in JFrame and in JApplet.• To add a menu bar to a top-level container, a JMenuBar object is

created, populated with menus, and then the set JMenuBar ()method is invoked.

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General-purpose

• The general-purpose containers are used to addother lightweight components like JButton, andJTextField. Eventually the general -purposecontainers are added to a top-level container.

• The various general-purpose containers havedifferent functionality depending on their use, for example a JPanel is an intermediate container

to group components.




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JFrame -1

• A JFrame is a top-level Container used to create a GUI-basedapplication. It is available in the javax.swing package.

• A Swing based GUI application can be developed by using twodistinct approaches:

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Extending javax.swing.Jframe Declaring javax.swing.Jfrarne

public class WinApp extends JFrame {

// Instance Data...

public WinApp() {

//

}

public static void main(String[]args){

WinApp app = new WinApp();

}

}

public class WinApp extends

SomeOtherClass{

// Instance Data

public static void main(String[]

args) {

JFrame frame = newJFrame();

}

}

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JFrame -2

• There are three basic things to be carried out on a frame. – Create a frame :JFrame frmWindow = new JFrame("Login"); – Display a frame

frmWindow. setSize(200,200)

frmWindow.setVisible(true); – Close the frame. By default the close operation of the JFrame is not

functional. To provide the close functionality you use the followingmethod:

frmWindow.setDefaultCloseOperation(JFrame.EXIT_0N_CL0SE);

• Note that components cannot be added to the JFramedirectly. They have to be added to the content-pane of JFrame.




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JApplet

• An Applet is a Java program which is meant to run as part of aweb-page. While using Swing, the javax. applet. JApplet classis used to create an Applet. Once created this Applet isembedded in the web page with the <applet> tag.

• The methods of JApplet class are: – init() – start() – paint() – stop() – destroy()

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public class MyApplet extends JApplet { public void init() {

//} public void start() {

//}

}

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JPanel -1

• The JPanel class is both a container and a component. Other components like JButton, JTextField and so on can be added toJPanel. JPanel in turn is added to a top-level container, or evenanother JPanel for nesting purposes.

• A JPanel is a rectangular opaque component, without any visible

border by default. However you can add a border for demarcation.Several different types of borders are available.

• Adding components to a JPanel first and then adding it to a top-levelcontainer is more advantageous than adding components directly.




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JPanel -2

•

A JPanel instance is created by invokingits default constructor.

• The default layout manager of JPanel is

FlowLayout.

• By default the JPanel as a component is

visible. You can make it invisible by usingthe setVisible (boolean) method. If

boolean parameter is set to true, JPanel

is visible else it is not visible. 1919

import javax.swing.JPanel;

JPanel myPanel; myPanel = new JPanel();

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Lightweight Components

• Swing components are referredto as lightweight components.Lightweight components render (draw) themselves with pure Javacode.

• The advantages of Lightweightcomponents are that they do notconsume extra overheads interms of memory and executiontime.

• They are platform independent.

•

Their 'Pluggable-Look-And-Feel‘capabilities allow to virtuallycopy the look and feel of any operating system on other operating systems.

• All the Lightweight components in the javax.swing package start with theletter J, like JButton, JTextField and so on.




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JLabel

• The JLabel is a component to display static text in a GUI-based application. AJLabel can also display an icon, or both text and icon.

• public String getText();

• public void setText(String label);




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Delegation Event Model

•

The model for event processing in version 1.0 of the AWTis based on inheritance. In order for a program to catchand process GUI events, it must subclass GUIcomponents and override either action() or handleEvent()methods.

• Three participants in the event delegation model: – event source: class that broadcasts events – event listeners: classes that receive event notifications – event object : class that describes the event

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JButton - 1

•

A JButton is a rectangular component with a text or icon as its label, andcan fire an event when clicked with a mouse.

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Imagelcon icon = newImagelcon("/images/ok.gif");// Create a button with an image on it.JButton lblName = new JButton("Name", icon);// Add the button to a containergetContentPane().add(lblName);

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JButton - 2

• Since JButton is a Swing component, the Event-Delegation Model is usedto handle its events.

• The JButton component listens using the java.awt.event.ActionListener interface..MyActionListener implement ActionListener{

actionPerformed(){//

}}

• This interface has one method named actionPerformed().What should happen when a button is pressed is specified in the action-code, and this code is specified in the actionPerformed() method.

• The JButton has a method addActionListener(), which is used to register thelistener object.btnMyAction.addActionListener(new MyActionListener())




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JCheckbox

• The JCheckBox component creates a component which can have only twostates(checked,unchecked)

• JCheckBox provides a convenient way toperform multiple selections of choices. Thechoices of JCheckBox are not mutually exclusive. A user can select none, all, or any combination

• boolean isSelected()void setSelected( boolean state)

• Add ItemListener

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JCheckBox chkBold;

chkBold = new JCheckBox {"Bold");

container.add(chkBold);

// Anonymous ClasschkBold.addltemListener{new

ItemLi3tener{) {

public void iteiriScateChanged

(ItemEvent e) {

// Action Code

}

}

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JRadioButton -1

• The JRadioButton component creates a component which can have onlytwo states, either checked or unchecked, by default it is unchecked.JRadioButton radPlain, radBold;

ButtonGroup group;

radPlain = new JRadioButton("Plain", true);

container.add(radPlain);

radBold = new JRadioButton("Bold");

container.add(radBold);

group = new ButtonGroup();

group.add(radPlain);

group.add(radBold);

• The JRadioButton class has methods:ü boolean isSelected()

ü void setSelected(boolean state)




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JRadioButton-2

• A JRadioButton component listens using either java.awt.event.ActionListener or java.awt.event.ItemListener interface.

• The java.awt.event.ItemListener has one method:void itemStateChanged(ItemEvent e)The method itemStateChanged() contains the action code as to what should happen when aJRadioButton component is selected or deselected.

• A JRadioButton has two methods for registering listener-objects namely, addActionListener () and

addltemListener().• If a listener-object is registered with a JRadioButton component, then whenever the component's

state changes from selected to deselected or vice versa, this method is invoked as part of thedelegation

radPlain.addltemListener(new ItemListener() {

public void iternStateChanged (ItemEvent e) {

// Action Code

}

}.




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JTextField

• A JTextField component allows to input and edit a single line of text.Normally text is inputted by the user, however you can also set text in aJTextField programmatically.

• A JLabel and a JTextField go hand-in-hand in most data-entry forms, for theuser to enter textual information.

• The important methods of the JTextFieid are enumerated below:ü String getText() - returns the contents of the JTextField.ü void setText (String text) - programmatically sets the text inü void setEditable (boolean editable) - if false then one cannot type or edit the

contents of the JTextFieid.




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JTextArea

• A JTextArea component allows to input and edit a multiple lines of text.Normally text is entered by the user; however you can also set text in aJTextArea prograrnmatically.




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JPasswordField

• A JPasswordField is similar to a JTextField in appearance. When the user types, the asterisk character (*) is echoed for every character typed.

• By default the asterisk character is echoed, it can be programmaticallychanged to any other character desired.

• Important methods public char[] getPassword ()

public void setText(String text)

public void setEchoChar (char c)

• A JPasswordField listens for eventsusing Java.awt.event.ActionListener interfaceIt has the method addActionListener ()toregister a listener-object, and if registered thewhen the user presses the 'Enter' key in their JPasswordFieid the control is delegated tothe method actionPerformed().


C f S



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Common Methods of SwingComponents

• setIcon() is used to set the icon image of a component

• setMnemonic() . Mnemonics allows one character in the components labelto be underlined. The component can be either clicked with a mouse or alternately with the Alt key and the mnemonic character combination

• setToolTipText() A Tool Tip is a visual textual feedback from a component

when the mouse cursor hovers over a component.• setBackground() is used to set the background color of the component.

• setForeground() is used to set the foreground color of the component.

• setBorder()

• setEnabled()

•

setFont()• setVisible()




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Pluggable look and feel

• Pluggable Look and Feel feature enhancesthe look and behavior of the GUI elementsin an application

•

Appearance of GUI components is referredas the “look”

• Behavior of GUI component is referred asthe “feel”

• Multiple look and feels are enabled inSwing architecture by separating everycomponent into two distinct classes

–

JComponent subclass –

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Pluggable look and feel

• Look and feels provided by Sun’s JavaRuntime Environment (JRE) are:

– CrossPlatformLookAndFeel: is same as the “JavaL&F” and is same across all platforms

– SystemLookAndFeel: is native to the system onwhich it is running

– Synth: allows the user to create their own lookand feel with an XML file

– Multiplexing: allows you to extend thecapabilities of user interface created in Swingwithout having the need to create a new lookand feel at the same time




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Nimbus Pluggable L&F

• Is a look and feel based on Synth• Provides a polished look to applications• Can be displayed at any resolution•

Is drawn using Java 2D vector graphics• Features of this L&F are:

– Easy customization - colors, icons, and fonts arestored in UIDefaults table that can be easily

customized – Easy to skin - since all colors, fonts, borders, and

painters are available in UIDefaults table, these valuescan be used




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Activating Nimbus L&F

• Three ways by which Nimbus L&F can beactivated are:

• Using UIManager class – Invoke the setLookAndFeel() method from the

UIManager class to set the Nimbus L&F present injavax.swing.plaf.nimbus.NimbusLookAndFeel

package

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...try {

UIManager.setLookAndFeel("javax.swing.plaf.nimbus.NimbusLookAndFeel");

} catch (Exception e) {

// handle exception

}

...

Snippet

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Activating Nimbus L&F

• Using swing.properties file• Specify the classname as the value for swing.defaultlaf in the

swing.properties file

• Place the file in the <jre install>\lib folder

² Using Command Line option³ Set the Nimbus L&F from the command line

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...

#Swing properties

swing.defaultlaf = javax.swing.plaf.nimbus.NimbusLookAndFeel

...

Snippet

java

-Dswing.defaultlaf=com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel

Snippet

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UIManager Class [1-3]

• Responsible for setting the current Swing L&F• Maintains a set of available look and feel classes• Maintains default values in a table, called

UIDefaults table of Swing components for particular look and feel

• Provides different getter/setter and other accessory methods that enable an application tomaintain a Swing L&F




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• Commonly used method of the UIManager classis getInstalledLookAndFeels()

– Method returns an array of objects of the availableLookAndFeelInfo class

–

LookAndFeelInfo class is a static nested class of UIManager class – LookAndFeelInfo class provides information on installed look

and feels




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• getInstalledLookAndFeels() method returns

an array of available look and feel class names• if condition checks whether the class name retrieved isequal to Nimbus

• setLookAndFeel() method sets the current lookand feel to Nimbus

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...

for (LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {

if ("Nimbus".equals(info.getName())) {

UIManager.setLookAndFeel(info.getClassName());

break;

}

}...

Snippet

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Summary

• The JFC is graphical framework which includes the older AWT, Swing andJava2D.

• Swing is framework based on the Model-View-Controller architecture

• MVC Architecture decomposes the above three functionality into threedistinct object: the Model, View and Controller.

•

A Container is meant to contain components. There are two types of Containers, Top-Level Container and General-Purpose Containers.

• Swing provides three top-level Containers JFrarae, JDialog and JApplet.

• There are several general-purpose containers like JPanel, JLayeredPane,JInternalFrame and JDeskTopPane.

• Lightweight components: JButton, JTextField, Jpassword,…

• How to add Action to each component

• How to use the Look&Feel features.




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Next…

• We are going to learn about – LayoutManager to manage Compoenent on

Container Component –

Swing Menu Components




References

• The Java™ Tutorials

• Using Swing Components

• Java Swing Tutorial

• OReilly: Java Swing, 2nd Edition

• APJ_I Class Notes

http://download.oracle.com/javase/tutorial/uiswing/


http://download.oracle.com/javase/tutorial/uiswing/components/

http://www.javabeginner.com/java-swing/java-swing-tutorial




http://download.oracle.com/javase/tutorial/uiswing/components/




Session1 Module1 Intro to Swing

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