Dated: 04/23/2001

Extends Applet.

Applets that use Swing must be subclasses of JApplet.

To add a compenent, do not invoke add() method of the Applet.

Instead call add() for content pane.

Container getContentPane ()

void add (Component comp) // add() of Container

Icons are encapsulated by the ImageIcon class, which paints an icon from an image.

Constructors:

ImageIcon (String filename)

ImageIcon (URL url)

Sample Code

import java.awt.*;

import javax.swing.*;

/*

<applet code="JLabelDemo" width=300 height=200>

</applet>

*/

public class JLabelDemo extends JApplet {

public void init () {

Container contentPane = getContentPane ();

ImageIcon ii = new ImageIcon ("image.gif");

JLabel jl = new JLabel ("My Image", ii, Jlabel.CENTER);

ContentPane.add (jl);

}

}

JButton

JButton(Icon i)

JButton(String s)

JButton(String s,Icon i)

void setActionCommand (String actionCommand)

A tabbed Pane is a component that appears as a group of folders. Each folder has a title. When a user selects a folder, its contents become visible. Only one of the folders may be selected at a time. Tabbed panes are used for setting configuration options.

Tabbed panes are encapsulated by the JTabbedPane Class, which extends JComponent.

void addTab(String str, Component comp)

Typically a JPanel or a subclass of it is added.

The general procedure to use a tabbed pane:-

1. Create a JTabbedPane object.
2. Call addTab () to add a tab to the pane. (The argument to this method define the title of the tab and the component it contains)
3. Repeat for each tab.
4. Add the tabbed pane to the content pane of the applet.

Sample Code

import java.swing.*;

/*

<applet code= "JTabbedPaneDemo" width=400 height=100>

</applet>

*/

public class JTabbedPaneDemo extends JApplet {

public void init() {

JTabbedPane jtp = new JTabbedPane();

jtp.addTab ("Cities", new CitiesPanel());

jtp.addTab ("Colors",new ColorsPanel());

getContentPane().add(jtp);

}

class CitiesPanel extends JPanel {

public CitiesPanel () {

JButton b1 = new JButton ("New York");

}

}

class ColorsPanel extends JPanel {

public ColorsPanel () {

JButton jb1 = new JButton ("Red");

}

}

Scroll Panes are implemented in swing by the JScrollPane class, which extends JComponents.

JScrollPane(Component comp)

JScrollPane(int vsb, int hsb)

JScrollPane(Component comp, int vsb, int hsb)

vsb and hsb are int constants with follwing possible values:

HORIZONTAL_SCROLLBAR_ALWAYS

HORIZONTAL_SCROLLBAR_AS_NEEDED

VERTICAL_SCROLLBAR_ALWAYS

VERTICAL_SCROLLBAR_AS_NEEDED

import java.awt.*;

import javax.swing.*;

/*

<applet code= "JScrollPaneDemo" width=400 height=100>

</applet>

*/

public class JScrollPaneDemo extends JApplet {

public void init () {

Container contentPane = getContentPane();

ContentPane.setLayout(new BorderLayout());

JPanel jp = new JPanel();

jp.setLayout(new GridLayout(20,20));

int b = 0;

for (int i = 0;i < 20; i++) {

for (int j = 0;j < 20; j++) {

jp.add(new JButton("Button" + b));

++b;

int v = ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED;

int h = ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED;

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

ContentPane.add(jsp,BorderLayout.CENTER);

}

}

A tree is a component that presents a hierarchical view of data.

Implemented in swing by the JTree class, which extends JComponent.

JTree (Hashtable ht)

JTree (Object obj[])

JTree (TreeNode tn)

JTree (Vector v)

The addTreeExpansionListener() and removeTreeExpansionListener() methods allow listeners to register and unregister for these notifications.

void addTreeExpansionListener(TreeExpansionListener tel)

void removeTreeExpansionListener(TreeExpansionListener tel)

TreePath getPathForLocation(int x, int y)

This method is used to translate a mouse click on a specific point of the tree to a tree path.

The TreeNode interface declares methods that obtain information about the tree node.

The MutableTreeNode interface extends TreeNode. It declares methods that can insert and remove child nodes or change the parent node.

The DefaultMutableTreeNode class implements the MutableTreeNode interface. It represents a node in a tree.

Sample Code

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

import javax.swing.tree.*;

/*

<applet code="JTreeEvents" width=400 height=200>

</applet>

*/

public class JTreeEvents extends JApplet {

JTree tree;

JTextField jtf;

public void init() {

int v = ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED;

void doMouseClicked (MouseEvent me) {

TreePath tp = tree.getPathForLocation (me.getX(), me.getY());

if (tp != null) {

}

}