Swing

3 Cube Computer Institute Website: www.3cci.in
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 javax.swing and its subpackages, such as javax.swing.JTree.

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 doesn’t support scrolling but this can be done
using ScrollPane.
Components can be added directly on the Window While adding component to window or Frame, they
or Frame. 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 Menu item can have images or radio button or check
check boxes. 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 “panes,” 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:
java.lang.Object
java.awt.Component
java.awt.Container
java.awt.Panel
java.applet.Applet
javax.swing.JApplet

Reference: The Complete Reference, Java Doc


Example:
Import java.awt.*;
Import javax.swing.*;
//<Applet code=MyClass width=300 height=300></Applet>

public class MyClass extends JApplet
{
JLabel l1 = new JLabel (“First Label”);
public void init( )
{
Container con = getContentPane ( );
con.setLayout (new FlowLayout ( ));
con.add (l1);
}
}

Difference between Applet and JApplet:

Applet JApplet
Applet doesn’t have rich functionality as JApplet is with rich functionality.
JApplet.
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:
java.lang.Object
java.awt.Component
java.awt.Container

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 Container’s LayoutManager
void removeAll () Removes all Components

Example:
You can give above example.


JWindow:
JWindow class is similar to the JFrame class. It uses a JRootPane for component management and
implements the RootPaneContainer.Basically it is top level window with no andorment s.JWindow class adds
no additional event handling capabilities beyond thoes of the JFrame and Window Classes.

Hierarchy:
java.lang.Object
java.awt.Component
java.awt.Container
java.awt.Window
java.swing.JWindow

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 javax.swing.*;

public class TopLevelWindows {

public static void main(String[] args) {

JFrame f = new JFrame("The Frame");
f.setSize(300, 300);
f.setLocation(100, 100);

JWindow w = new JWindow( );
w.setSize(300, 300);
w.setLocation(500, 100);

f.setVisible(true);
w.setVisible(true);

}
}


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:
java.lang.Object
java.awt.Component
java.awt.Container
java.awt.Window
java.awt.Frame
javax.swing.JFrame

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:

public class JFrameDemo {



f.setVisible(true);
}
}


JPanel:
The Swing equivalent of AWT’s 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:
java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.JComponent
javax.swing.JPanel

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:

public class JPanelDemo {


JPanel p = new JPanel();
f.add(p);

f.setVisible(true);
}
}


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 and/or an icon.

Hierarchy:

java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.JLabel

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)


Example:
import java.awt.*;

/*
<applet code="JLabelDemo" width=300 height=50>
</applet>
*/

public class JLabelDemo extends JApplet {
JLabel l1;
ImageIcon i1;
public void init() {

// Get content pane
Container contentPane = getContentPane();
contentPane.setLayout(new FlowLayout());

// Add Label to content pane
i1=new ImageIcon(“sunset.jpg”);
j1= new JLabel(i1);
contentPane.add(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:
java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.text.JTextComponent
javax.swing.JTextField

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)


Example:
import java.awt.*;

/*
<applet code="JTextFieldDemo" width=300 height=50>
</applet>
*/

public class JTextFieldDemo extends JApplet {
JTextField jtf;

// Get content pane
contentPane.setLayout(new FlowLayout());

// Add text field to content pane
jtf = new JTextField("This is JTextField ",15);
contentPane.add(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:

java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.AbstractButton
javax.swing.JButton

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:

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:

java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.JToggleButton
javax.swing.JCheckBox

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:


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:

java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.JToggleButton
javax.swing.JRadioButton
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:


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:

java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.JComboBox

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:


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:
java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.JTabbedPane

Constructors:

JTabbedPane ()
Creates an empty TabbedPane with a default tab placement of JTabbedPane.TOP.
JTabbedPane (int tabPlacement)
Creates an empty TabbedPane with the specified tab placement of either: JTabbedPane.TOP,
JTabbedPane.BOTTOM, JTabbedPane.LEFT, or JTabbedPane.RIGHT.
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:


9) JScrollPane:

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

Hierarchy:

java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.JScrollPane

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)


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:

java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.JTree

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:


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:
java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.JTable

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.


Example:

import java.awt.*;

/*
<applet code="JTableDemo" width=400 height=200>
</applet>
*/
public class JTableDemo extends JApplet {


// Get content pane

// Set layout manager
contentPane.setLayout(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 = ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED;
int h = ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED;

JScrollPane jsp = new JScrollPane (table, v, h);

// Add scroll pane to the content pane
contentPane.add (jsp, BorderLayout.CENTER);

}
}


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:

java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.JList
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:



Example:

import java.awt.*;
import java.awt.event.*;

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();
topPanel.setLayout( 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 );
topPanel.add( listbox, BorderLayout.CENTER );
setSize( 300, 100 );
setVisible( true );
}

public static void main( String args[] )
{
// Create an instance of the test application
ListDemo ld = new ListDemo ();
}

}


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