Today's Objectives

1
Today's Objectives

• Understand how a Java application differs from a
  Java applet.
• Learn the basics of Java event processing and
  Swing.
• Learn how to use JDeveloper to create an
  applet/Java application.

2
Applet

• Applets display AWT objects in an Applet. Applet
  is a subclass of the Container class.
• Applets execute within an Internet Browser or
  Appletviewer.
• An applet tag is used to embed a reference to the
  applet in a .html file e.g. myPage.html.

3
Java Application

• Java applications display AWT objects in a Frame.
  Frame is a subclass of the Container class.
• Java applications are executed by the Java
  interpreter.
• java applicationname

4
AWT Overview
Label
Container
Text field
First
Panel
Last
ID
Canvas
E-Mail
Check box
ISMG 6020
Start Browse
Button
ISMG 6140
Modify
5
Container for My Dept EJB
6
Applet Structure

• Applet is a type of panel (container)
• Applet adds AWT/Swing components to itself.
• Sample Code to Establish the Display Button
• XYLayout xYLayout1 new XYLayout()
• JButton displayButton new JButton()
• displayButton.setText("Display")
• this.getContentPane().add(displayButton, new
  XYConstraints(105, 294, 107, -1))

7
JDeveloper

• Select layout manager type.
• Select interface component style and type AWT
  button, SWING textfield, AWT checkbox, etc.
• Click on panel to insert interface component into
  applet. Use mouse to move and stretch component.
  
• Click on the interface component. In the
  property list dialog box, set values for the
  interface component.
• e.g., displayButton is object name
• "Display" is text value of displayButton
• Drag displayButton to desired position (as
  aforementioned)

8
Layout Managers

• Absolute Positioning (none) arranges components
  by pixel position. Demo
• Box Layout either stacks its components on top of
  each other (with the first component at the top)
  or places them in a tight row from left to right
  -- your choice. Demo
• Flow layout arranges components from left to
  right in rows. The rows are aligned left, right,
  or centered. Works like a typewriter. Demo
• Grid Layout arranges components in a table of
  equal-size cells. Rows are filled top to bottom,
  columns left to right. Demo
• Border Layout arranges components by geographic
  position (North, South, East, West) Demo
• e.g., add("North", new Button("First"))
• Card Layout arranges components by a tabbed card
  deck. Demo
• Grid Bag Layout arranges components in a grid.
  Components are placed in cells as specified by
  cell coordinates, not pixel coordinates. Demo

9
AWT/Swing Methods for Developing Event Handlers
10
Integer Manipulation

• Accept an integer value from the user
• Int id (Integer.valueOf(textField.getText().tri
  m())).intValue()
• Display an integer value to the user
• textField.setText(String.valueOf(result))

11
FYI Simple Event Handling JDK 1.1

• The action method in JDK 1.02 is replaced with
  actionPerformed method.
• public void actionPerformed(ActionEvent e)
• Object object event.getSource()
• if (object button1)
• onButton1()
• else if (object button2)
• onButton2()

12
Advanced Event Handling in JDK 1.1

• Choose a listener object (applet, button, etc.)
  for a GUI event which the applet wants to
  monitor, e.g. button, mouse, etc. The listener
  object contains methods for handling all events
  associated with the GUI object.
• In the UI Editor open the applet,
• Double click on the button to create and register
  the listener for that event.
• When the event occurs, the event handler of the
  listener object is invoked directly.

13
In-Class Demo

• Create Applet
• Create HTML file to run the applet
• Connect to EJB
• Create simple form for accepting dept id.
• Add a display button to the form and bind the
  button to the appropriate event handler.

14
Add Department Popup Dialog Box
15
Dialog Box

• Develop a new class derived from JDialog.
• Use GUI builder and a Layout manager to define
  the form. Add Ok and Cancel buttons.
• Set properties visible true and modal true
  for the JDialog form.
• Add public attributes to the JDialog derived
  class for exchange of data.
• Program OK button listener to copy the user input
  to the public attributes of the JDialog class.

16
addDeptDlgBox

• public class addDeptDlgBox extends JDialog
• public long deptNo
• public String dname
• public String loc
• public boolean OK
• XYLayout xYLayout1 new XYLayout()
• JButton cancelButton new JButton()
• JButton okButton new JButton()

17
Action Listeners for addDeptDlgBox Buttons

• void OKButton_actionPerformed(ActionEvent e)
• deptNo (Integer.valueOf(this.deptNoTxtField.getT
  ext().trim())).intValue()
• dname this.dnameTxtField.getText()
• loc this.locTxtField.getText()
• OK true
• setVisible(false)
• void CancelButton_actionPerformed(ActionEvent
  e)
• setVisible(false)
• OK false

18
Applet Use of Dialog Box

• void AddButton_actionPerformed(ActionEvent e)
• addDeptDlgBox dlb new addDeptDlgBox()
• dlb.setModal(true)
• dlb.setVisible(true)
• if (dlb.OK)
• try dept deptHome.create( dlb.deptNo )
• dept.setDname(dlb.dname)
• dept.setLoc(dlb.loc)
• catch (Exception ex) labelErrorMsg.setVisible
  (true)