GUI-Based Event Driven Programming

8/19/2019 GUI-Based Event Driven Programming

1/58

GUI-Based Event-Driven Programming

http://rds.yahoo.com/_ylt=A0S020we3v9IYnUAA0SJzbkF;_ylu=X3oDMTBza3M3YnJoBHBvcwMxMzgEc2VjA3NyBHZ0aWQDSTA5N18xMTg-/SIG=1iq1fl362/EXP=1224814494/**http:/images.search.yahoo.com/images/view?back=http://images.search.yahoo.com/search/images?p=java+duke&ni=20&ei=UTF-8&fr=yfp-t-501&xargs=0&pstart=1&b=121&w=70&h=50&imgurl=www.javasource.150m.com/downloadfiles/student%20parking%20gui/duke_pencil.gif&rurl=http://www.javasource.150m.com/download.htm&size=2.2kB&name=duke_pencil.gif&p=java+duke&type=gif&oid=7fb04235f20ab6c8&no=138&tt=1,228&sigr=11b1c732g&sigi=12dqu2eu8&sigb=13bac1l9rhttp://rds.yahoo.com/_ylt=A0S020we3v9IYnUAA0SJzbkF;_ylu=X3oDMTBza3M3YnJoBHBvcwMxMzgEc2VjA3NyBHZ0aWQDSTA5N18xMTg-/SIG=1iq1fl362/EXP=1224814494/**http:/images.search.yahoo.com/images/view?back=http://images.search.yahoo.com/search/images?p=java+duke&ni=20&ei=UTF-8&fr=yfp-t-501&xargs=0&pstart=1&b=121&w=70&h=50&imgurl=www.javasource.150m.com/downloadfiles/student%20parking%20gui/duke_pencil.gif&rurl=http://www.javasource.150m.com/download.htm&size=2.2kB&name=duke_pencil.gif&p=java+duke&type=gif&oid=7fb04235f20ab6c8&no=138&tt=1,228&sigr=11b1c732g&sigi=12dqu2eu8&sigb=13bac1l9r


2/58

Event . The user’s interaction with the GUIcomponent.

Event-handling Methods . Methods that arecalled when an event occurs.

The user interacts with a GUI component, the

program is notified of the event and theprogram processes the event.


3/58

public class Frame extends JFrame implements ActionListener

A class can inherit existing attributes andbehaviors from another class via extends , and can

implement one or more interfaces.

In the class definition above, JFrame class will beinherited and interface ActionListener will be

implemented.

http://rds.yahoo.com/_ylt=A0S020u53_9I3PIADn2JzbkF;_ylu=X3oDMTBzZzgwMmhjBHBvcwMyMTMEc2VjA3NyBHZ0aWQDSTA5N18xMTg-/SIG=1i42g6nfg/EXP=1224814905/**http:/images.search.yahoo.com/images/view?back=http://images.search.yahoo.com/search/images?p=java+duke&ni=20&ei=UTF-8&fr=yfp-t-501&xargs=0&pstart=1&b=201&w=123&h=128&imgurl=student.educ.umu.se/~sanann00/images/duke.jpg&rurl=http://student.educ.umu.se/~sanann00/dependencies.html&size=9.9kB&name=duke.jpg&p=java+duke&type=JPG&oid=581f3667c98a4ad2&no=213&tt=1,234&sigr=11mg3psqe&sigi=11df3i068&sigb=13bus36b1http://rds.yahoo.com/_ylt=A0S020u53_9I3PIADn2JzbkF;_ylu=X3oDMTBzZzgwMmhjBHBvcwMyMTMEc2VjA3NyBHZ0aWQDSTA5N18xMTg-/SIG=1i42g6nfg/EXP=1224814905/**http:/images.search.yahoo.com/images/view?back=http://images.search.yahoo.com/search/images?p=java+duke&ni=20&ei=UTF-8&fr=yfp-t-501&xargs=0&pstart=1&b=201&w=123&h=128&imgurl=student.educ.umu.se/~sanann00/images/duke.jpg&rurl=http://student.educ.umu.se/~sanann00/dependencies.html&size=9.9kB&name=duke.jpg&p=java+duke&type=JPG&oid=581f3667c98a4ad2&no=213&tt=1,234&sigr=11mg3psqe&sigi=11df3i068&sigb=13bus36b1


4/58

Class JFrame is from the package javax.swing

JFrame provides the basic attributes andbehaviors of a window – a title bar andbuttons to minimize, maximize and closethe window.

http://rds.yahoo.com/_ylt=A0S020yP3_9Ivm0AvhKJzbkF;_ylu=X3oDMTBzZ2IxajRpBHBvcwMxNDYEc2VjA3NyBHZ0aWQDSTA5N18xMTg-/SIG=1io83a6s9/EXP=1224814863/**http:/images.search.yahoo.com/images/view?back=http://images.search.yahoo.com/search/images?p=java+duke&ni=20&ei=UTF-8&fr=yfp-t-501&xargs=0&pstart=1&b=141&w=55&h=50&imgurl=www.javasource.150m.com/downloadfiles/student%20parking%20gui/duke_point.gif&rurl=http://www.javasource.150m.com/download.htm&size=1.2kB&name=duke_point.gif&p=java+duke&type=gif&oid=a455006d5347dc14&no=146&tt=1,234&sigr=11b1c732g&sigi=12ce8i9ji&sigb=13b4g5kh7http://rds.yahoo.com/_ylt=A0S020yP3_9Ivm0AvhKJzbkF;_ylu=X3oDMTBzZ2IxajRpBHBvcwMxNDYEc2VjA3NyBHZ0aWQDSTA5N18xMTg-/SIG=1io83a6s9/EXP=1224814863/**http:/images.search.yahoo.com/images/view?back=http://images.search.yahoo.com/search/images?p=java+duke&ni=20&ei=UTF-8&fr=yfp-t-501&xargs=0&pstart=1&b=141&w=55&h=50&imgurl=www.javasource.150m.com/downloadfiles/student%20parking%20gui/duke_point.gif&rurl=http://www.javasource.150m.com/download.htm&size=1.2kB&name=duke_point.gif&p=java+duke&type=gif&oid=a455006d5347dc14&no=146&tt=1,234&sigr=11b1c732g&sigi=12ce8i9ji&sigb=13b4g5kh7


5/58

Interface . Specifies one or more behaviors that youmust define in your class definition.

This interface specifies that this class must define amethod with the heading:

public void actionPerformed (ActionEvent e){}

The methods task is to process a user’s interaction witha GUI component that generates an action event.

The method is called automatically in response to theuser’s interaction.



6/58

Sets the window’s size.

Syntax :

setSize (width, height);



7/58

By default a window is NOT displayed on thescreen, it can be displayed using thesetVisible method.

Syntax :

setVisible (true);



8/58

Displays the text in the title bar of thewindow.

Syntax :

setTitle (“text on title bar”);



9/58

Displays the text in the title bar of thewindow.

Should be the first statement of theconstructor.

Syntax :

super (“text on title bar”) ;



10/58

When a window is no longer needed in anapplication , it must be explicitly disposed of.

This can be done by explicitly calling themethod setDefaultCloseOperation with theargument JFrame.EXIT_ON_CLOSE



11/58

From package java.awt

Use to attach a GUI component on thecontent pane so they can be displayed atexecution time

Syntax:Container = getContentPane ( );

getContentPane ().A method that returns areference to the content pane that can beused to attach GUI component

http://rds.yahoo.com/_ylt=A0S020yP3_9Ivm0AvhKJzbkF;_ylu=X3oDMTBzZ2IxajRpBHBvcwMxNDYEc2VjA3NyBHZ0aWQDSTA5N18xMTg-/SIG=1io83a6s9/EXP=1224814863/**http:/images.search.yahoo.com/images/view?back=http://images.search.yahoo.com/search/images?p=java+duke&ni=20&ei=UTF-8&fr=yfp-t-501&xargs=0&pstart=1&b=141&w=55&h=50&imgurl=www.javasource.150m.com/downloadfiles/student%20parking%20gui/duke_point.gif&rurl=http://www.javasource.150m.com/download.htm&size=1.2kB&name=duke_point.gif&p=java+duke&type=gif&oid=a455006d5347dc14&no=146&tt=1,234&sigr=11b1c732g&sigi=12ce8i9ji&sigb=13b4g5kh7http://rds.yahoo.com/_ylt=A0S020yP3_9Ivm0AvhKJzbkF;_ylu=X3oDMTBzZ2IxajRpBHBvcwMxNDYEc2VjA3NyBHZ0aWQDSTA5N18xMTg-/SIG=1io83a6s9/EXP=1224814863/**http:/images.search.yahoo.com/images/view?back=http://images.search.yahoo.com/search/images?p=java+duke&ni=20&ei=UTF-8&fr=yfp-t-501&xargs=0&pstart=1&b=141&w=55&h=50&imgurl=www.javasource.150m.com/downloadfiles/student%20parking%20gui/duke_point.gif&rurl=http://www.javasource.150m.com/download.htm&size=1.2kB&name=duke_point.gif&p=java+duke&type=gif&oid=a455006d5347dc14&no=146&tt=1,234&sigr=11b1c732g&sigi=12ce8i9ji&sigb=13b4g5kh7


12/58

Used to define the layout manager for the applet’suser interface.

Layout Mana ger . Provided to arrange GUIcomponents on the Container for presentationpurposes. This determines the position and size of every GUI component attached to the container.

Syntax:

Object of Container.setLayout (new FlowLayout ( ) );



13/58

The most basic layout manager

GUI components are placed on the containerfrom left to right in the order in which theyare attached to the container via the methodadd.

When the edge of the container is reached,components are continued to the next line.



14/58

Contains a string of character to display on thescreen.

Normally indicates the purpose of another GUI

component on the screen.Syntax:

JLabel object_name; // declaration

object_name = new JLabel (“String to display”) ;



15/58

JLabel label1;label1 = new JLabel (“Enter a value”);

To attach this to the content pane, use add method:

Syntax:

Object of Container. add(object of JLabel);

Example, if c is the content pane, to add the new JLabellabel1, use:

c.add (label1);



16/58



17/58


18/58

JTextField field1;field1 = new JTextField (10);


Syntax:

Object of Container. add(object of JTextField);

Example, if c is the content pane, to add the new JTextField field1, use:

c.add (field1);



19/58



20/58

Used to determine if user can edit entries in the JTextField.

false value means the user cannot edit entries inthe JTextField (gray background), a true valuemeans user can edit entries (white background)

Syntax:

JTextField_object.setEditable (true/false);

Example:field1.setEditable (false);



21/58

Rectangular object that the user can press toperform an action

Syntax:

JButton object_name; // declaration

object_name = new JButton(“ Text on Button”) ;



22/58

JButton button1;button1 = new JButton (“Click here”);


Syntax:

Object of Container. add(object of JButton);

Example, if c is the content pane, to add the new

JButton button1, use:c.add (button1);



23/58



24/58

Specifies that the program should listen for events The keyword this enables the program to refer toitself

When the user interacts with a GUI component anevent is sent to the program

Example:button1.addActionListener (this);

When the user press the button, an event is sent to the appletindicating that an action was performed by the user and callsthe method actionPerformed to process user interaction.



25/58

Used to specify the tool tip that is displayedautomatically when the user positions the mousecursor over the label in the GUI

Syntax :Object of GUI .setToolTipText (“Text”);

Example:

labek1.setToolTipText("DLSU - Dasmariñas");



26/58

Used to get input from the JTextField

Syntax:object of JTextField.getText()

Example:

JTextField field1;int num;num = Integer.parseInt (field1.getText ( ));

Note:

Any input from a JTextField is a String.



27/58

Used to display string of information on the JTextField

Syntax:

object of JTextField.setText (“String to display”);

Example:field1.setText (“De La Salle”);

Note:

JTextField can only display String.



28/58

Used to convert integer values to string.

JTextField can ONLY display Strings.

Example:

num = 10;field1.setText(Integer.toString (num));



29/58

Used to convert numeric values to string.

Example:

num = 10;field1.setText(String.valueOf (num));



30/58

From java.awt

Used to define the background color andforeground color that will be used by the GUIcomponent.



31/58


32/58

black blue

cyan darkGray gray green lightGray

magenta pink orange red white yellow



33/58

Syntax 2:

object.setBackground(new Color (R,G,B));

Examples:

c.setBackground(new Color(0,128,64));field1.setBackground(new Color(0,128,64));

Note: RGB values are the RED, GREEN and BLUEcomponents of a Color (values are from 0 to 255)



34/58

Defines the foreground color of the GUIcomponents.

Syntax 1:

object.setForeground(Color.predefined color);

Examples:

c. setForeground(Color.yellow);field1. setForeground(Color.blue);



35/58

Syntax 2:

object.setForeground(new Color (R,G,B));

Examples:

c.setForeground(new Color(0,128,64));field1.setForeground(new Color(0,128,64));

Note: 0,0,0 is black255, 255, 255 is white



36/58

From java.awt.

Use to define the font name, font style and font size of the textthat will be used by a GUI component.

Syntax:

Font = new Font ( "Font Name", Font Style, Font Size);

Example:

Font font = new Font ("Trebuchet MS", Font.BOLD, 24);

Note:

Available Font Style are: Font.BOLD, Font.ITALIC, Font.PLAIN



37/58

Font.BOLD 1

Font.ITALIC 2

Font.PLAIN 0

Font.BOLD + Font.ITALIC 3



38/58

Use to set the Font defined by the Font class.

Syntax:

Object of GUI.setFont(object of Font Class);

Example:

Font font = new Font ("Trebuchet MS", Font.BOLD, 24);Label1.setFont(font);



39/58

import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JTextField; import javax.swing.JButton;

import java.awt.FlowLayout; import java.awt.Container; import java.awt.Font; import java.awt.Color;

import java.awt.event.ActionListener; import java.awt.event.ActionEvent;



40/58

Package: javax.swing Consists of a label positioned beside a circle;you can click the cirlce to select or deselect

Syntax 1:

//no label, unselected Example:


41/58

Syntax 2:

Example:

Syntax 3:

//with label, selected Example:


42/58


43/58

Syntax 2:

Example:

Syntax 3:

//with label, selected Example:


44/58

JCheckBox and JRadioButton have the sameset of properties and methods.

Methods and properties that can be appliedto JRadioButton object can also be applied to

JCheckBox object.


45/58


46/58

sets the state of the JCheckBox to true forselected or false for unselected

Syntax:object.setSelected(boolean);

Example:


47/58


48/58

Determines which object generated the event


49/58

Determines whether the event was a selectionor a deselection

Returns an integer that is equal to two classvariables:◦ ItemEvent.SELECTED◦ ItemEvent.DESELECTED


50/58

Package: javax.swing Used to groups several components, such as JCheckBoxes, so a user can select only one ata time.

When you groupd JCheckBox objects, all ofthe other JCheckBoxes are automaticallyturned off when the user selects any onecheckbox.


51/58

Syntax:ButtonGroup object = new ButtonGroup();GUI_object.add(buttonGroup_object);

Example:


52/58

Method of JList which is used to determine the number of items that are visible in the list.

Example:

colorList.setVisibleRowCount(5);

5 rows are initially displayed



53/58

This method of JList specifies the list selection mode. Needs:import javax.swing.ListSelectionModel;

Possible values are:

1) SINGLE_SELECTION2) SINGLE_INTERVAL_SELECTION3) MULTIPLE_INTERVAL_SELCTION

Example:colorList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);



54/58

From javax.swing:

import javax.swing.JScrollPane;

Object that is used to provide the automaticscrolling functionality for the JList.

Example:

c.add(new JScrollPane(colorList));



55/58

This is used to register an event thatimplements a ListSelectionListener.

Calls the valueChanged methodautomatically to process the event.

Example:

colorList.addListSelectionListener(this);



56/58

Returns the selected item;s index in the list.public void valueChanged (ListSelectionEvent e){if (colorList.getSelectedIndex() == 0)

c.setBackground(Color.blue);}

-OR-

Color color[]= {Color.blue, Color.cyan, Color.green, Color.magenta};

public void valueChanged (ListSelectionEvent e){c.setBackground(color[colorList.getSelectedIndex()]);}



57/58


58/58

From java.awtImport java.awt.Toolkit;

Example:

setIconImage(Toolkit.getDefaultToolkit().getImage(“lasalle.jpg"));

Documents

GUI-Based Event Driven Programming