Swing

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Reference The Complete Reference Java Doc

1 Introduction to Swing

Swing

Swing is a set of classes that provides more powerful and flexible components than are possible with the

AWT In addition to the familiar components such as buttons check boxes and labels Swing supplies

several exciting additions including tabbed panes scroll panes trees and tables

Unlike AWT components Swing components are not implemented by platform-specific code Instead they

are written entirely in Java and therefore are platform-independent The term lightweight is used to describe

such elements

The Swing-related classes are contained in javaxswing and its subpackages such as javaxswingJTree

Difference between Awt and Swing

Awt Swing

Native component Pure Java component

Components are heavy weight Components are light weight

Native look and feel Pure java component

Does not have complex component It has additional components like JTree JTable

JProgressBar and JSlider ect

Applet can not have menu JApplet can contain menu

Components like Button can not have images Components like JButton can have images

List has scrollbar JList doesnrsquot support scrolling but this can be done

using ScrollPane

Components can be added directly on the Window

or Frame

While adding component to window or Frame they

have to be added on its ContentPane

Does not have SplitPane or TabbedPane Has SplitPane or TabbedPane

Do not have MDI window MDI can be achieved using JInternalFrame Object

Menu item can not have images or radio button or

check boxes

Menu item can have images or radio button or check

boxes

JApplet

Fundamental to Swing is the JApplet class which extends Applet JApplet is rich with functionality that is

not found in Applet For example JApplet supports various ldquopanesrdquo such as the content pane the glass

pane and the root pane

Unlike Applet BorderLayout is default layout of JApplet

When adding a component to an instance of JApplet do not invoke the add ( ) method of the applet Instead

call add ( ) for the content pane of the JApplet object The content pane can be obtained via the method

shown here

Container getContentPane ( )

Hierarchy

javalangObject javaawtComponent javaawtContainer javaawtPanel javaappletApplet javaxswingJApplet

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Example

Import javaawt

Import javaxswing

ltApplet code=MyClass width=300 height=300gtltAppletgt

public class MyClass extends JApplet

JLabel l1 = new JLabel (ldquoFirst Labelrdquo)

public void init( )

Container con = getContentPane ( )

consetLayout (new FlowLayout ( ))

conadd (l1)

Difference between Applet and JApplet

Applet JApplet

Applet doesnrsquot have rich functionality as

JApplet

JApplet is with rich functionality

We add component to Applet We add component to ContentPane

We can not add MenuBar We can add JMenuBar to JApplet

LayoutManager is set to Applet LayoutManager is set to JApplet

Default Layout is FlowLayout Default Layout is BorderLayout

Container

The Container class is a subclass of the Component class that is used to define components that have the

capability to contain other components It provides methods for adding retrieving displaying counting and

removing the components that it contains The Container class also provides methods for working with

layouts The layout classes control the layout of components within a container

Hierarchy

javalangObject javaawtComponent javaawtContainer

The methods of the class Container are

Component add (Component c) Adds the component to the end of this container

void setLayout (LayoutManager m) Re-Sets the Containerrsquos LayoutManager

void removeAll () Removes all Components

Example

You can give above example

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JWindow

JWindow class is similar to the JFrame class It uses a JRootPane for component management and

implements the RootPaneContainerBasically it is top level window with no andorment sJWindow class adds

no additional event handling capabilities beyond thoes of the JFrame and Window Classes

Hierarchy

javalangObject javaawtComponent javaawtContainer javaawtWindow javaswingJWindow

Constructor

JWindow()

Creates a window with no specified owner

JWindow(Frame owner)

Creates a window with the specified owner frame

JWindow(GraphicsConfiguration gc)

Creates a window with the specified GraphicsConfiguration of a screen device

Methods

setSize(int height int width) setLocation(int x int y) setVisible(boolean state)

Example

import javaxswing public class TopLevelWindows public static void main(String[] args) JFrame f = new JFrame(The Frame) fsetSize(300 300) fsetLocation(100 100) JWindow w = new JWindow( ) wsetSize(300 300) wsetLocation(500 100) fsetVisible(true) wsetVisible(true)

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JFrame

Simply put if you know how to use the AWT Frame class then you can use JFrame JFrame is an extended version of Frame only JFrame exhibits a slight incompatibility when compared to the AWT Frame class because it contains only a single child (which is an instance of JRootPane) In order to add any other components to the JFrame instance they must be added to the root pane Hierarchy

javalangObject javaawtComponent javaawtContainer javaawtWindow javaawtFrame javaxswingJFrame

Constructor JFrame() Constructs a new frame that is initially invisible JFrame(GraphicsConfiguration gc) Creates a Frame in the specified GraphicsConfiguration of a screen device and a blank title JFrame(String title) Creates a new initially invisible Frame with the specified title JFrame(String title GraphicsConfiguration gc) Creates a JFrame with the specified title and the specified GraphicsConfiguration of a screen device Methods

setLayout(LayoutManager manager) setSize(int height int width) setLocation(int x int y) setVisible(boolean state)

Example

import javaxswing public class JFrameDemo public static void main(String[] args) JFrame f = new JFrame(The Frame) fsetSize(300 300) fsetLocation(100 100) fsetVisible(true)

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JPanel

The Swing equivalent of AWTrsquos Panel class is JPanel With few exceptions everything you know about Panel applies equally to JPanel JPanel supports all of the AWT layout managers and also the new layouts provided by Swing

Hierarchy javalangObject javaawtComponent javaawtContainer javaxswingJComponent javaxswingJPanel

Constructor

JPanel()

Creates a new JPanel with a double buffer and a flow layout

JPanel(LayoutManager layout)

Create a new buffered JPanel with the specified layout manager

Methods

setLayout(LayoutManager manager) add(Component c) Example import javaxswing public class JPanelDemo public static void main(String[] args) JFrame f = new JFrame(The Frame) JPanel p = new JPanel() fadd(p) fsetSize(300 300) fsetLocation(100 100) fsetVisible(true)

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Reference The Complete Reference Java Doc

1) Icons

In Swing icons are encapsulated by the ImageIcon class which paints an icon from an image Two of its constructors are shown here Constructors

ImageIcon(String filename) ImageIcon(URL url) The first form uses the image in the file named filename The second form uses the image in the resource identified by url

Methods

int getIconHeight( ) int getIconWidth( )

2) JLabel Swing labels are instances of the JLabel class which extends JComponent It can display text andor an icon Hierarchy

javalangObject javaawtComponent javaawtContainer javaxswingJComponent javaxswingJLabel

Constructors

JLabel () Creates a JLabel instance with no image and with an empty string for the title

JLabel (Icon image) Creates a JLabel instance with the specified image

JLabel (String text) Creates a JLabel instance with the specified text

JLabel (String text Icon icon) Creates a JLabel instance with the specified text and icon

Method

Icon getIcon ( ) String getText ( ) void setIcon (Icon i) void setText (String s)

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Reference The Complete Reference Java Doc

Example import javaawt import javaxswing ltapplet code=JLabelDemo width=300 height=50gt ltappletgt public class JLabelDemo extends JApplet JLabel l1 ImageIcon i1 public void init() Get content pane Container contentPane = getContentPane() contentPanesetLayout(new FlowLayout()) Add Label to content pane i1=new ImageIcon(ldquosunsetjpgrdquo) j1= new JLabel(i1) contentPaneadd(j1) 3) JTextField The Swing text field is encapsulated by the JTextComponent class which extends JComponent It provides functionality that is common to Swing text components One of its subclasses is JTextField which allows you to edit one line of text

Hierarchy

javalangObject javaawtComponent javaawtContainer javaxswingJComponent javaxswingtextJTextComponent javaxswingJTextField

Constructors

JTextField () Constructs a new TextField JTextField (int columns) Constructs a new empty TextField with the specified number of columns JTextField (String text) Constructs a new TextField initialized with the specified text JTextField (String text int columns) Constructs a new TextField initialized with the specified text and columns

Method

String getText () Void setText (String s) int getColumns() void setColumns(int cols)

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Reference The Complete Reference Java Doc

Example import javaawt import javaxswing ltapplet code=JTextFieldDemo width=300 height=50gt ltappletgt public class JTextFieldDemo extends JApplet JTextField jtf public void init() Get content pane Container contentPane = getContentPane() contentPanesetLayout(new FlowLayout()) Add text field to content pane jtf = new JTextField(This is JTextField 15) contentPaneadd(jtf) 4) JButton Swing buttons provide features that are not found in the Button class defined by the AWT For example you can associate an icon with a Swing button Swing buttons are subclasses of the AbstractButton class which extends JComponent

Hierarchy

javalangObject javaawtComponent javaawtContainer javaxswingJComponent javaxswingAbstractButton javaxswingJButton

Constructors

JButton ()

Creates a button with no set text or icon JButton (Icon icon)

Creates a button with an icon JButton (String text)

Creates a button with text JButton (String text Icon icon)

Creates a button with initial text and an icon Methods

String getText( ) void setText(String s)

Example

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Reference The Complete Reference Java Doc

5) JCheckBox

The JCheckBox class which provides the functionality of a check box is a concrete implementation of AbstractButton Its immediate superclass is JToggleButton which provides support for two-state buttons (checked or unchecked) Hierarchy

javalangObject javaawtComponent javaawtContainer javaxswingJComponent javaxswingAbstractButton javaxswingJToggleButton javaxswingJCheckBox

Constructors JCheckBox () Creates an initially unselected check box button with no text no icon JCheckBox (Icon icon) Creates an initially unselected check box with an icon JCheckBox (Icon icon boolean selected) Creates a check box with an icon and specifies whether or not it is initially selected JCheckBox (String text) Creates an initially unselected check box with text JCheckBox (String text boolean selected) Creates a check box with text and specifies whether or not it is initially selected JCheckBox (String text Icon icon) Creates an initially unselected check box with the specified text and icon JCheckBox (String text Icon icon boolean selected) Creates a check box with text and icon and specifies whether or not it is initially selected Methods

void setSelected(boolean state) void setLabel(String label) void setIcon(Icon icon) boolean isSelected()

Example

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Reference The Complete Reference Java Doc

6) JRadioButton

Radio buttons are supported by the JRadioButton class which is a concrete implementation of AbstractButton Its immediate superclass is JToggleButton which provides support for two-state buttons Radio buttons must be configured into a group Only one of the buttons in that group can be selected at any time The ButtonGroup class is instantiated to create a button group Its default constructor is invoked for this purpose Elements are then added to the button group via the following method

void add(AbstractButton ab) Hierarchy

javalangObject javaawtComponent javaawtContainer javaxswingJComponent javaxswingAbstractButton javaxswingJToggleButton javaxswingJRadioButton

Constructors JRadioButton () Creates an initially unselected radio button with no set text JRadioButton (Icon icon) Creates an initially unselected radio button with the specified image but no text JRadioButton (Icon icon boolean selected) Creates a radio button with the specified image and selection state but no text JRadioButton (String text) Creates an unselected radio button with the specified text JRadioButton (String text boolean selected) Creates a radio button with the specified text and selection state JRadioButton (String text Icon icon) Creates a radio button that has the specified text and image and that is initially unselected JRadioButton (String text Icon icon boolean selected) Creates a radio button that has the specified text image and selection state Methods

void setSelected(boolean state) void setLabel(String label) void setIcon(Icon icon)

boolean isSelected() Example

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Reference The Complete Reference Java Doc

7) JComboBox

Swing provides a combo box (a combination of a text field and a drop-down list) through the JComboBox class which extends JComponent A combo box normally displays one entry However it can also display a drop-down list that allows a user to select a different entry You can also type your selection into the text field Hierarchy

javalangObject javaawtComponent javaawtContainer javaxswingJComponent javaxswingJComboBox

Constructors

JComboBox () Creates a JComboBox with a default data model JComboBox (Object [] items) Creates a JComboBox that contains the elements in the specified array JComboBox (Vector items) Creates a JComboBox that contains the elements in the specified Vector

Methods

Object getItemAt (int index) int getItemCount () int getSelectedIndex () Object getSelectedItem ()

addItem (Object anObject) Example

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8) JTabbedPane

A tabbed pane is a component that appears as a group of folders in a file cabinet Each folder has a title when a user selects the folder its contents become visible Only one of the folders may be selected at a time Tabbed panes are commonly used for setting configuration options Tabbed panes are encapsulated by the JTabbedPane class which extends JComponent Hierarchy

javalangObject javaawtComponent javaawtContainer javaxswingJComponent javaxswingJTabbedPane

Constructors

JTabbedPane () Creates an empty TabbedPane with a default tab placement of JTabbedPaneTOP JTabbedPane (int tabPlacement) Creates an empty TabbedPane with the specified tab placement of either JTabbedPaneTOP JTabbedPaneBOTTOM JTabbedPaneLEFT or JTabbedPaneRIGHT JTabbedPane (int tabPlacement int tabLayoutPolicy) Creates an empty TabbedPane with the specified tab placement and tab layout policy Methods void addTab(String title Component component) void addTab(String title Icon icon Component component) void addTab(String title Icon icon Component component String tip) Example

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Reference The Complete Reference Java Doc

9) JScrollPane A scroll pane is a component that presents a rectangular area in which a component may be viewed Horizontal andor vertical scroll bars may be provided if necessary Scroll panes are implemented in Swing by the JScrollPane class which extends JComponent

Hierarchy

javalangObject javaawtComponent javaawtContainer javaxswingJComponent javaxswingJScrollPane

Constructors JScrollPane () Creates an empty (no viewport view) JScrollPane where both horizontal and vertical scrollbars appear when needed JScrollPane (int vsbPolicy int hsbPolicy) Creates an empty (no viewport view) JScrollPane with specified scrollbar policies Methods JScrollBar getVerticalScrollBar () void setVerticalScrollBar (JScrollBar bar) JScrollBar getHorizontalScrollBar () void setHorizontalScrollBar (JScrollBar bar)

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10) JTree A tree is a component that presents a hierarchical view of data A user has the ability to expand or collapse individual subtrees in this display Trees are implemented in Swing by the JTree class which extends JComponent

Hierarchy

javalangObject javaawtComponent javaawtContainer javaxswingJComponent javaxswingJTree

Constructors JTree () Returns a JTree with a sample model JTree (TreeNode root) Returns a JTree with the specified TreeNode as its root which displays the root node Methods int getRowCount() int getRowForLocation(int x int y) TreePath getPathForLocation (int x int y) Example

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Reference The Complete Reference Java Doc

11) JTable A table is a component that displays rows and columns of data You can drag the cursor on column boundaries to resize columns You can also drag a column to a new position Tables are implemented by the JTable class which extends JComponent

Hierarchy javalangObject javaawtComponent javaawtContainer javaxswingJComponent javaxswingJTable

Construstors JTable () Constructs a default JTable that is initialized with a default data model a default column model and a default selection model JTable (int numRows int numColumns) Constructs a JTable with numRows and numColumns of empty cells using DefaultTableModel JTable (Object [][] rowData Object[] columnNames) Constructs a JTable to display the values in the two dimensional array rowData with column names columnNames JTable (Vector rowData Vector columnNames) Constructs a JTable to display the values in the Vector of Vectors rowData with column names columnNames

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Reference The Complete Reference Java Doc

Example import javaawt import javaxswing ltapplet code=JTableDemo width=400 height=200gt ltappletgt public class JTableDemo extends JApplet public void init() Get content pane Container contentPane = getContentPane() Set layout manager contentPanesetLayout(new BorderLayout()) Initialize column headings String[] colHeads = Name Phone Fax Initialize data Object[][] data = Gail 4567 8675 Ken 7566 5555 Viviane 5634 5887 Melanie 7345 9222 Anne 1237 3333 John 5656 3144 Matt 5672 2176 Claire 6741 4244 Erwin 9023 5159 Ellen 1134 5332 Jennifer 5689 1212 Ed 9030 1313 Helen 6751 1415 Create the table JTable table = new JTable (data colHeads) Add table to a scroll pane int v = ScrollPaneConstantsVERTICAL_SCROLLBAR_AS_NEEDED int h = ScrollPaneConstantsHORIZONTAL_SCROLLBAR_AS_NEEDED JScrollPane jsp = new JScrollPane (table v h) Add scroll pane to the content pane contentPaneadd (jsp BorderLayoutCENTER)

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12) JList A list box is simply a user interface control containing a collection of similar items from which the user can make one or more selections This is the premise behind the AWT List control which presents a Java component equivalent to list box objects found in all other graphics interfaces Lists are implemented by the JList class which extends JComponent

Hierarchy

javalangObject

javaawtComponent javaawtContainer

javaxswingJComponent javaxswingJList

Constructor JList() Constructs a JList with an empty model JList(ListModel dataModel) Constructs a JList that displays the elements in the specified non-null model JList(Object[] listData) Constructs a JList that displays the elements in the specified array JList(Vector listData) Constructs a JList that displays the elements in the specified Vector Methods

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Reference The Complete Reference Java Doc

Example import javaawt import javaawtevent import javaxswing class ListDemo extends JFrame Instance attributes used in this example JPanel topPanel JList listbox Constructor of main frame public ListDemo () Create a panel to hold all other components topPanel = new JPanel() topPanelsetLayout( new BorderLayout() ) getContentPane()add( topPanel ) Create some items to add to the list String listData[] = Item 1 Item 2 Item 3 Item 4 Create a new list box control listbox = new JList( listData ) topPaneladd( listbox BorderLayoutCENTER ) setSize( 300 100 ) setVisible( true ) public static void main( String args[] ) Create an instance of the test application ListDemo ld = new ListDemo ()