copyright 2003 mudra services1 swing why was swing/jfc introduced? many complex additional...

Copyright 2003 Mudra Services

1

SWING

Why was SWING/JFC introduced? Many complex additional components like

tables, trees, internal frames, split panes etc Cross-platform A common look and feel across platforms

(Metal) A lightweight framework which does not use the

native peer objects JavaBean compliant. This makes building GUI

applications using an IDE very simple. Borland JBuilder and Symantec VisualCafe are examples of IDEs


2

Model-View-Controller (MVC)

Model Stores the state of the component. For example

in a push button, the state can be ON or OFF View

Visual representation of the model on the screen. This is the LOOK of the component

Controller Event handling for the entire component. This is

the FEEL of the component. In case of a pushbutton, controller detects the button press and informs the model that the state has changed


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MVC - Diagram


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MVC - Swing

View can change without changes in model and controller

SWING api provides the ability to completely change the View and Controller parts of the component without changing the model. The Look and Feel (L&F) of the component is changed. SWING supports pluggable look and feel.

Replace the model without replacing the view and controller.


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MVC - Swing

Every SWING component comes with a default Model, View and Controller

In SWING, the View and the Controller are combined to create a Delegate object. Model-Delegate architecture.

This makes the architecture simple


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MVC - SWING Extends from Container


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JComponent

All SWING components inherit from Jcomponent

Responsible for the pluggable look and feel of the components

Responsible for handling keyboard events for each component

Responsible for handling borders around components

Controlling the size of the component Accessibility support for the blind


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JComponent

Every SWING Component extends from the Container class of AWT (not Component class)

All SWING Components start with the letter ‘J’


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Windows Look And Feel


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Metal Look And Feel


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Motif Look And Feel


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SWING

How do we create SWING containers and components?

Use SWING component and container constructors

How do we layout the SWING components within a container?

Use layout Managers (same as AWT layout managers)

How does the java code interact with the components?

1.1 AWT Event Model (same as AWT)


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SWING - Example

package swingexample;

import javax.swing.*;import java.awt.*;

public class SwingExample extends JFrame {

public SwingExample() { this.getContentPane().setLayout(new

FlowLayout(FlowLayout.CENTER));

// create componets JLabel textLabel = new JLabel("Click to submit "); JButton clickButton = new JButton("Submit");

All Components start with ‘J’


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SWING - Example

// add components to container this.getContentPane().add(textLabel); this.getContentPane().add(clickButton); }

public static void main(String[] s) { SwingExample example = new SwingExample(); example.setTitle("A Sample Frame");

// show the container on the screen example.pack(); example.setVisible(true); }}


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SWING - Example

Events are generated by event sources just like AWT

Listeners are used in SWING in a similar way as in AWT


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SWING – Component interaction

package swingexample;import javax.swing.*;import java.awt.*;import java.awt.event.*;

public class SwingExample extends JFrame implements

ActionListener,WindowListener { private JLabel textLabel; private JButton clickButton;

public SwingExample() { this.getContentPane().setLayout(new

FlowLayout(FlowLayout.CENTER));


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// create componets textLabel = new JLabel("Click to submit "); clickButton = new JButton("Submit");

// add a listener clickButton.addActionListener(this);

// add components to container this.getContentPane().add(textLabel); this.getContentPane().add(clickButton);

// add a listener to the window this.addWindowListener(this);

}


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public static void main(String[] s) { SwingExample example = new SwingExample(); example.setTitle("A Sample Frame");

// show the container on the screen example.pack(); example.setVisible(true); }


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public void actionPerformed(ActionEvent e) { if (textLabel.getText().startsWith("Click")) { textLabel.setText("Changed Text"); textLabel.setForeground(Color.blue); } else { textLabel.setText("Click to submit "); textLabel.setForeground(Color.black); } }

public void windowClosing(WindowEvent e) { this.dispose(); this.setVisible(false); System.exit(0); }


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// all methods we do not care about public void windowDeactivated(WindowEvent e) {} public void windowActivated(WindowEvent e) {} public void windowDeiconified(WindowEvent e) {} public void windowIconified(WindowEvent e) {} public void windowClosed(WindowEvent e) {} public void windowOpened(WindowEvent e) {}}

Adapter ClassesUseful when some methods need to be implemented from a set of methods in the listener interface.


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SWING - Listeners

Listeners are usually implemented as Inner classes

Adapter classes A class which implements a listener interface but

provides null implementations for all the methods Subclasses of adapter usually implement only a few

of the many methods Saves time by not typing all the methods

Anonymous Inner classes A very tiny implementation of a listener


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SWING – Listeners as Inner classes

class WindowHandler implements WindowListener { public void windowClosing(WindowEvent e) { dispose(); setVisible(false); System.exit(0); }

// all methods we do not care about public void windowDeactivated(WindowEvent e) {} public void windowActivated(WindowEvent e) {} public void windowDeiconified(WindowEvent e) {} public void windowIconified(WindowEvent e) {} public void windowClosed(WindowEvent e) {} public void windowOpened(WindowEvent e) {} }

Inner class of SwingExample.java


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SWING - Adapters

Adapters save time WindowAdapter implements

WindowListener but provides null method implementations

class WindowHandler extends WindowAdapter { public void windowClosing(WindowEvent e) { dispose(); setVisible(false); System.exit(0); } }

Notice that other methods are not required here


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SWING – Anonymous Inner classes

Create the listener object at the place where it is added to the component

// add a listener to the window

this.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { dispose(); setVisible(false); System.exit(0); } });

Think of this as a block of codepassed as parameter – which is executed later. Much like functionPointers.


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SWING - JFrame

Extends from the Frame class (in AWT) Supports swing menubars which can be

moved around JFrame contains only one child object

called JRootPane When a SWING component is to be

added to the JFrame, always use as

frame.getContentPane().add(component);


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SWING - JPanel

Equivalent to Panel in AWT but does not extend from Panel class

Can be associated with a LayoutManager

Basically contains many SWING components

Do not mix SWING components with the AWT components.


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SWING - JPanel

JPanel topPanel = new JPanel();topPanel.setLayout(new GridLayout(3,2));topPanel.add(new JButton(“One”));topPanel.add(new JButton(“Two”));topPanel.add(new JButton(“Three”));topPanel.add(new JButton(“Four”));topPanel.add(new JButton(“Five”));topPanel.add(new JButton(“Six”));


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SWING - Layout

All of the 5 layouts of AWT can be used in SWING applications FlowLayout GridLayout BorderLayout CardLayout GridBagLayout


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SWING - BoxLayout

BoxLayout New layout in SWING Organizes the components along the X or Y

axis of the owner panel Alignment can be left, right or center

justified Will not wrap components to the next line.

Instead the components will be reduced to their minimum size


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SWING - BoxLayout

Four checkbox items are being added here in a panel with Boxlayout


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SWING - BoxLayout

package swingboxexample;

import java.awt.*;import javax.swing.*;

public class SwingboxExample extends JFrame {

public SwingboxExample() {

// BoxLayout panel JPanel panel = new JPanel(); panel.setLayout(new BoxLayout(panel,BoxLayout.Y_AXIS));


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SWING - BoxLayout

panel.add(new JCheckBox("Pattern match")); panel.add(new JCheckBox("Search whole worlds only")); panel.add(new JCheckBox("Case sensitive")); panel.add(new JCheckBox("Search only selected text"));

this.getContentPane().add(panel); }

public static void main(String[] args) { SwingboxExample swingboxExample = new SwingboxExample();

swingboxExample.pack(); swingboxExample.setVisible(true); }}


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SWING - BoxLayout

Box A JPanel with BoxLayout

JPanel panel = new JPanel();

panel.setLayout(new BoxLayout(panel,BoxLayout.Y_AXIS));

Can be replaced by

Box panel = new Box(BoxLayout.Y_AXIS);


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SWING - Borders

Can be applied to any SWING component In most cases, a border is added to a JPanel object Border types

BevelBorder – 3D border supports raised/lowered look EmptyBorder – reserves space around the component EtchedBorder – etched line look LineBorder – line border of arbitrary thickness MatteBorder – tiling of specified icon or color TitledBorder – with a title CompoundBorder – nested border


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SWING - Border

Add the following line to BoxLayout example panel.setBorder(new BevelBorder(BevelBorder.LOWERED));


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SWING - Border

Instead of creating a border object every time, it is convenient and efficient to use a border factory object Reduces number of Border objects created

UseBorder bevel =

BorderFactory.createLoweredbevelBorder();

Instead of Border bevel = new BevelBorder(BevelBorder.LOWERED));


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SWING - CompoundBorder

Multiple borders can be applied to the same component

Useful when creating border with white space around the component

Again, use the BorderFactory to create a compound object instead of the constructor


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SWING - CompoundBorder

Add the following code to the BoxLayout examplepanel.setBorder(BorderFactory.createCompoundBorder

(BorderFactory.createLoweredBevelBorder() ,BorderFactory.createEmptyBorder(20,20,20,20)));

Outer

Inner


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SWING - JLabel

Can contain an image as well as text Font and colors of the text can be controlled Text and image can be aligned Image can be disabled (a gray filter is used

on the image dynamically) Constructors

JLabel label = new JLabel(“label1”);JLabel label = new

JLabel(“label1”,image,SwingConstants.CENTER);[where Icon image = new ImageIcon(“image1.gif”);]


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SWING - JLabel

Setting Fonts and Colorslabel.setFont(new Font(“Dialog”,Font.PLAIN,12));label.setBackground(Color.blue);

Setting Text Alignmentlabel.setHorizontalAlignment(SwingConstants.RIGHT)label.setVerticalAlignment(SwingConstants.TOP)

Disabling the iconlabel.setDisabledIcon(imageIcon);


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SWING - Buttons


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SWING - AbstractButton

All operations which are common to JButton, JToggleButton, JCheckBox, JRadioBox are included here.

Use ActionListener to handle events from a Button

button.addActionListener(listener); Enable or Disable buttons

button.setEnabled(false); Set Mnemonic

button.setMnemonic(‘R’); // Use ALT R to operate


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SWING - JButton

Represents a Push Button Important Constructors

JButton(Icon icon) JButton(String text) JButton(String text,Icon image)


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SWING - JButton

Add the following code clickButton = new JButton("Submit",new

ImageIcon("AppletIcon.gif")); clickButton.setMnemonic('S');


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SWING - JToggleButton

Operation is a toggle operation State is toggled It is parent for JCheckBox and JRadioBox.

Both these buttons also exhibit toggling behavior

Important Constructors JToggleButton(Icon icon) JToggleButton(Icon icon,boolean selected) JToggleButton(String txt,Icon icon,boolean selected)


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SWING - JToggleButton

Create ButtonGroups. Used to group multiple toggle buttons together. When a new button is pressed, all other buttons in the same group are untoggled.

ButtonGroup group = new ButtonGroup(); group.add(button1); group.add(button2); group.add(button3);


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SWING - JCheckBox

Represents a check box control Use check boxes to apply multiple

simultaneous states Important Constructors

JCheckBox(Icon icon) JCheckBox(String text) JCheckBox(String text,boolean selected) JCheckBox(Icon icon,boolean selected) JCheckBox(String txt,Icon icon,boolean selected)


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SWING - JRadioButton

Represents a radio button control Always used with a ButtonGroup Use the radio boxes to apply mutually

exclusive states Important Constructors

JRadioButton(Icon icon) JRadioButton(String text) JRadioButton(String text,boolean selected) JRadioButton(Icon icon,boolean selected) JRadioButton(String txt,Icon icon,boolean selected)


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SWING – Button Example


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package swingbutton;

import java.awt.*;import javax.swing.*;import javax.swing.border.*;

public class SwingButton extends JFrame {

public SwingButton() {

// main panel JPanel mainPanel = new JPanel(); mainPanel.setLayout(new

BoxLayout(mainPanel,BoxLayout.Y_AXIS));


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// checkbox panel JPanel checkPanel = new JPanel(); checkPanel.setLayout(new

BoxLayout(checkPanel,BoxLayout.Y_AXIS)); checkPanel.setBorder(BorderFactory.createTitledBorder("Find"));

// add all checkboxes to the checkpox panel checkPanel.add(new JCheckBox("Pattern match")); checkPanel.add(new JCheckBox("Search whole worlds only")); checkPanel.add(new JCheckBox("Case sensitive")); checkPanel.add(new JCheckBox("Search only selected text"));

Createcheckpanel


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// create radio box panel JPanel radioPanel = new JPanel(); radioPanel.setLayout(new BoxLayout(radioPanel,BoxLayout.Y_AXIS)); radioPanel.setBorder(BorderFactory.createTitledBorder("Sex"));

JRadioButton maleB = new JRadioButton("Male"); JRadioButton femaleB = new JRadioButton("Female"); femaleB.setSelected(true); radioPanel.add(maleB); radioPanel.add(femaleB);

// create a button group for radio buttons ButtonGroup group = new ButtonGroup(); group.add(maleB); group.add(femaleB);

Createradiopanel


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// add to main panel mainPanel.add(checkPanel); mainPanel.add(radioPanel);

// add to JFrame content pane this.getContentPane().add(mainPanel); }

public static void main(String[] args) { SwingButton swingButton = new SwingButton();

swingButton.pack(); swingButton.setVisible(true); }}


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SWING - JTextComponent

AWT text support was limited JTextComponent contains all

knowledge and algorithms related to a text editor


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SWING - JTextComponent

Supports clipboard operations Interacts with the OS to interface with the

clipboard Cut,copy paste

Can save and load a file Contains all code for

text selection background colors selection color Read/Write to a stream


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SWING - JTextField

Only a single line of text Supports Unicode character set Can add a mnemonic to a field Important constructors

JTextField() JTextField(String text) JTextField(int columns)

Methods String text = field.getText()


57

SWING - JPasswordField

Extends from JTextField Similar to JTextField but does not echo

the characters on the field (instead displays a *)

Can set the display character passwordField.setEchoChar(‘$’);


58

SWING - JTextArea

Accepts more than one line of text Important constructor

JTextArea() JTextArea(String text) JTextArea(int rows,int cols)

Methods void append(text) Void replaceRange(String txt,int start,int end)


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SWING – Text Example


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package textexample;


public class TextExample extends JFrame {

public TextExample() { JPanel northPanel = new JPanel(); northPanel.setLayout(new GridLayout(2,2));


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// name label and field. create a mnemonic JLabel name = new JLabel("Name"); JTextField nameF = new JTextField(); name.setLabelFor(nameF); name.setDisplayedMnemonic('N'); nameF.setFocusAccelerator('N');

// name label and field. create a mnemonic JLabel addr = new JLabel("Address"); JTextField addrF = new JTextField(); addr.setLabelFor(addrF); addr.setDisplayedMnemonic('A'); addrF.setFocusAccelerator('A');

ALT-N will move thefocus to the name field

ALT-A will move thefocus to the addressfield


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northPanel.add(name);

northPanel.add(nameF); northPanel.add(addr); northPanel.add(addrF);

JPanel centerPanel = new JPanel(); centerPanel.setLayout(new BorderLayout()); centerPanel.add("Center",new JTextArea(20,20));

getContentPane().add("North",northPanel); getContentPane().add("Center",centerPanel); }


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public static void main(String[] args) { TextExample textExample = new TextExample(); textExample.pack(); textExample.setVisible(true); }

} // End


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SWING - Exercise

Create a JFrame as shown in the next page. Figure out the layout Manager for the different

panels in the User Interface. Associate mnemonics and accelerators to the

swing components as indicated in the interface. Notice that all the buttons are the same size. Use

setMinimumSize() and setMaximumSize() to set the size of the button.

Notice the defaults in the interface What listener will you implement to act on the

button clicks? How will you differentiate between the different button clicks?


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SWING - Exercise


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SWING - JComboBox

A superset of AWT’s Choice class When an item is selected, an ItemEvent

is sent to all the ItemListeners registered for the event

Can be editable Important constructors

JComboBox() JComboBox(ComboBoxModel model)


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SWING - JComboBox

Adding item to a combo box combo.addItem(“item”);

Removing an item from a combo box combo.removeItem(“item”); combo.removeItemAt(3); combo.removeAllItems();

Selecting items combo.setSelectedItem(“item”); combo.setSelectedIndex(3); int index = combo.getSelectedIndex() String item = (String)combo.getSelectedItem()


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SWING - JComboBox

Enable editing combo.setEditable(true)


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SWING - JProgressBar

Issues with a Time consuming task Useful when a time consuming task

requires a user to wait It indicates the progress that the task is

making It lets the user know that the program

has not frozen or stopped Important constructors

JProgressBar()


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SWING - JProgressBar

Methods int getValue() int getMinimum() int getMaximum() void setValue(int i)

Changes in progress bar is generated as ChangeEvent


71

SWING - Example

Example of the screen in the middle of the run


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SWING - Example

package progressexample;

import java.awt.*;import javax.swing.*;import javax.swing.border.*;import java.awt.event.*;

public class ProgressExample extends JFrame implements ActionListener {

private JLabel label = new JLabel("Progress"); private JButton button = new JButton("Start"); private JProgressBar pbar = null;


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SWING - Example

public ProgressExample() {

// create panel with box layout and border JPanel panel = new JPanel(); panel.setLayout(new BoxLayout(panel,BoxLayout.Y_AXIS)); panel.setBorder(BorderFactory.createEmptyBorder(20,20,20,20));

panel.add(label);

// add progress bar to panel pbar = new JProgressBar(); pbar.setMinimum(0); pbar.setMaximum(20); panel.add(pbar);


74

SWING - Example

button.addActionListener(this); panel.add(button);

getContentPane().add(panel); }

public static void main(String[] args) { ProgressExample progressExample = new ProgressExample();

progressExample.pack(); progressExample.setVisible(true); }


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SWING - Example

public void actionPerformed(ActionEvent e) { for (int j=0;j<20;j++) { // sleep for 1 sec try { Thread.sleep(1000); } catch(Exception exp) {}

// set the value of the progress bar and refresh immediately pbar.setValue(j+1); pbar.paintImmediately(new Rectangle(getWidth(),getHeight())); } }}

Simulating a time consuming task. Breakinto iterations.

Note that the user is not able to do anything else


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SWING - JSlider

Can be used to select from a range of values

When changing the values, it generates ChangeEvent.


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SWING - JSlider

Important constructors JSlider() JSlider(int orientation,int value,int min,int max)

Methods int getValue() void setValue(int value) int getMinimum() int getMaximum()


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SWING – JMenuBar,JMenu,JMenuItem

Menu at the top which provides all the functionality of the application

JMenuBar consructor JMenuBar()

JMenuBar methods JMenu add(JMenu menu)


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Output of the code


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package menuexample;


public class MenuExample extends JFrame {

public MenuExample() {

// create the menu bar JMenuBar menub = new JMenuBar();


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// create the file menu JMenu fileMenu = new JMenu("File"); fileMenu.add(new JMenuItem("Open")); fileMenu.add(new JMenuItem("New")); fileMenu.add(new JSeparator()); fileMenu.add(new JMenuItem("Save")); fileMenu.add(new JMenuItem("Save As")); fileMenu.add(new JMenuItem("Exit"));

// create the edit menu JMenu editMenu = new JMenu("Edit"); editMenu.add(new JMenuItem("Delete")); editMenu.add(new JMenuItem("Copy"));


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// create the tools menu JMenu toolsMenu = new JMenu("Tools"); toolsMenu.add(new JMenuItem("Generate Documentation")); toolsMenu.add(new JMenuItem("Generate Code"));

// create the help menu JMenu helpMenu = new JMenu("Help"); helpMenu.add(new JMenuItem("Help Documentation")); helpMenu.add(new JMenuItem("About ..."));

// add menus to the menu bar menub.add(fileMenu); menub.add(editMenu); menub.add(toolsMenu); menub.add(helpMenu);


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// set the menubar setJMenuBar(menub); }

public static void main(String[] args) { MenuExample menuExample = new MenuExample();

menuExample.setSize(200,200); menuExample.setVisible(true); }}


84


Menu Selection can be observed by adding action listener to the menu item

menuitem.addActionListener(this);

Set a tooltip for a menu item menuItem.setToolTipText(text);

Add a image to the menu item menuItem.setIcon(image); JMenuItem(String text,Icon image)


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Add a accelerator key to the menu item menuItem.setMnemonic(‘F’);

JCheckboxMenuItem Offers model operation from the menu JCheckBoxMenuItem(String text) JCheckBoxMenuItem(String text,Icon icon) menuitem.setState(false)


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JRadioButtonMenuItem Implement radio buttons from inside the

menu Use button groups to group multiple radio

button menu items JRadioButtonMenuItem(String text) JRadioButtonMenuItem(String text,Icon icon)


87

SWING - JPopupMenu

Context sensitive options for a given task

Pops up all the items on Right click (in windows)

Add JMenuItem objects to the Popup menu

Constructor JPopupMenu()


88

SWING - JPopupMenu


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SWING - JPopupMenu

package popupexample;import java.awt.*;import javax.swing.*;import java.awt.event.*;public class PopupExample extends JFrame {

private JPopupMenu popup = new JPopupMenu();

public class MouseHandler extends MouseAdapter { public void mouseReleased(MouseEvent e) { if (e.isPopupTrigger()) { popup.show(e.getComponent(),e.getX(),e.getY()); } } }


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SWING - JPopupMenu

public PopupExample() { setSize(300,300);

// add items to the popup JMenuItem openItem = new JMenuItem("Open"); JMenuItem saveItem = new JMenuItem("Save"); JMenuItem saveasItem = new JMenuItem("Save As"); JMenuItem closeItem = new JMenuItem("Close");

// add to popup menu popup.add(openItem); popup.add(saveItem); popup.add(saveasItem); popup.add(closeItem);


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SWING - JPopupMenu

getContentPane().add("Center",new JPanel()); getContentPane().addMouseListener(new

MouseHandler()); }

public static void main(String[] args) { PopupExample popupExample = new PopupExample();

// show popupExample.setVisible(true); }

}


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SWING - JToolBar

Most common features of the application are usually in the toolbar

Significantly improves the user interface No toolbar in AWT Tooltips for each item in the toolbar Dock and undock a toolbar Constructors

JToolBar()


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SWING - JToolBar

Method add(Component comp) addSeparator() setFloatable(false)


94

SWING - JToolBar


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SWING - JToolBar

JToolBar tool = new JToolBar();

tool.add(new JButton(new ImageIcon("open.gif"))); tool.add(new JButton(new ImageIcon("save.gif"))); tool.add(new JButton(new ImageIcon("saveall.gif"))); tool.addSeparator(); tool.add(new JButton(new ImageIcon("zoom.gif"))); tool.add(new JButton(new ImageIcon("zoomin.gif"))); tool.add(new JButton(new ImageIcon("zoomout.gif")));

getContentPane().add("North",tool);


96

SWING - Exercise Create a JFrame which changes a color as shown below.


97

SWING – Exercise

Each of the sliders associated with the red, blue and green color has a minimum value of 0 and maximum value of 255

As the user changes the slider value, the actual value must be displayed on the text label on the right of the slider

Provide implementation for “Apply” and “Cancel” which just closes the Jframe.

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