INFSY 547: WEB-Based Technologies Gayle J Yaverbaum, PhD Professor of Information Systems Penn State Harrisburg

Adding More Applets objects to XML Content <?xml version="1.0"?> <!DOCTYPE panelslayoutapplet SYSTEM "PanelLayoutsApplet.dtd"> <jclass> <app class="panellayoutsapplet.PanelLayoutsApplet“ width="300" height="250"> </app> <app class="firstapplet.FirstApplet" width="300" height="250"> <app class="urlapplet.URLApplet" width="300" height="250"> </jclass>

xsl Code <TR> <xsl:for-each select="app"> <TD width=“30%"> <applet> <xsl:attribute name="code"> <xsl:value-of select="@class"/> </xsl:attribute> <xsl:attribute name="width"> <xsl:value-of select="@width"/> <xsl:attribute name="height"> <xsl:value-of select="@height"/> </applet> </TD> </xsl:for-each> </TR>

Run Saxon Processor

Applet Considerations Javax.swing supplies best classes setSize is unnecessary but aids in debugging applet size is set in html

package guisampleapplet; import javax.swing.JApplet; import java.awt.*; public class GUISampleApplet extends JApplet { PanelClass p; public void init () p = new PanelClass(); }

Graphical User Example package guisampleapplet; import javax.swing.JApplet; import java.awt.*; public class GUISampleApplet extends JApplet { PanelClass p; public void init() p = new PanelClass(); this.setSize(300, 40); this.add("North", p); } Extending our code! BorderLayout

package guisampleapplet; import java.awt.Color; import java.awt.FlowLayout; import javax.swing.JButton; import javax.swing.JPanel; public class PanelClass extends JPanel { JButton _button1, _button2, _button3; JPanel _p; public PanelClass() { super(); _p = this; designPanel(); } private void designPanel() { _p.setBackground(Color.blue); _p.setLayout(new FlowLayout()); _button1 = new CreateAButton(_p, _button1, "Button 1 ",Color.orange); _button2 = new CreateAButton(_p, _button2, "Button 2 ", Color.GREEN); _button3 = new CreateAButton(_p, _button3, "Button 3 ", Color.YELLOW);

package guisampleapplet; import java.awt.Color; import javax.swing.JButton; import javax.swing.JPanel; public class CreateAButton extends JButton { public CreateAButton (JPanel p, JButton b, String str, Color c) super (str); this.setBackground(c); p.add (this); }

Layout Managers In JAVA Indicate layout of choice or accept default layout is set in setLayout method Indicate layout of choice or accept default Add () and remove () methods are common to all layouts.

Popular Layout Managers FlowLayout GridLayout BorderLayout

Panels A layout manager may apply to a panel or an applet as a whole An applet may be divided into panels which may themselves be divided into subpanels and so on.

Panels Labels, buttons and more may be added to containers (panels) Subsequently, panels are added to the applet

Complete all files to run your applet in a browser xml dtd xsl css bat Run the applet in the browser

Add a class to create a label Add labels between each button Remove button labels Change all button colors Line up each button and label – one/line using GridLayout (see next slide and page 285 of text)

GridLayout package gridlayoutexample; import javax.swing.JApplet; import javax.swing.JPanel; import java.awt.*; public class GridLayoutClass extends JApplet { CreateAButton b; JPanel j; public void init () this.setBackground (Color.white); j = new JPanel (); j.setLayout(new GridLayout(5, 2)); for (int i=1; i<=10; i++) b= new CreateAButton (j, i, Color.red, Color.white); j.add (b); } this.add(j);

package gridlayoutexample; import java.awt.Color; import javax.swing.JButton; import javax.swing.JPanel; public class CreateAButton extends JButton { public CreateAButton (JPanel p, int x, Color c, Color f) super ("Button " + x); this.setBackground(c); this.setForeground (f); }

Event Driven Programming Code that is called by the system when an event occurs An event signifies an occurrence The event generator notifies event handlers

Typical event handling Text field Object Event Handling Button Object JAVA AWT Environment: Messages are sent between JAVA Objects Screen OS Interrupt Event Notification Update Text Field Press Button (Buttons generate events) Typical event handling

Event Handling and Associated Objects Interface Events Flow User clicks a button User types text User uses a mouse When an event occurs, applet is notified Program may take action

Add implements action listener to the class public class PanelClass extends JPanel implements ActionListener 1. Add to the action code to: _button1.addActionListener(this); for designPanel method 2. Do this for all of your buttons

public void actionPerformed(ActionEvent e) { if (e.getSource() == _button1) _button1.setBackground (Color.red); _button2.setBackground (Color.blue); _button2.setBackground (Color.yellow); } Change all of the colors for each button clicked to a different color pattern

BorderLayout Manager o Divides the container (either a panel or whole applet) o Five areas - North -South -East -West -Center May also use the horizontal and vertical gaps as in FlowLayout

BorderLayout Manager North West South East Center

public void PlacePanels () { setLayout(new BorderLayout(5,10)); . } Note: 1. may simply be (new BorderLayout () 2. the 5,10 indicates border space in pixels

Pressing a mouse button triggers a mouse event Rather than implementing ActionListener, you will implement MouseListener (note that more than one listener may be implemented) When a mouse is pressed, the location is stored in x,y coordinates and location may be retrieved with getx () and gety (). MouseEvent handlers are invoked

Example on next slides demonstrate: Mouse enter Mouse exit Left mouse click Right mouse click

import java.applet.Applet; import java.awt.*; import java.awt.event.*; public class mousedemo extends Applet implements MouseListener { //note that this bracket will having matching end bracket next screen TextField mousetext; public void init(){ mousetext = new TextField(25); add(mousetext); addMouseListener(this); } public void mousePressed(MouseEvent e){ if((e.getModifiers()& InputEvent.BUTTON1_MASK) == InputEvent.BUTTON1_MASK){ mousetext.setText("Left mouse button down at " + e.getX() + "," + e.getY()); } else{ mousetext.setText("Right mouse button down at "

public void mouseClicked(MouseEvent e){ mousetext.setText("You clicked the mouse at " + e.getX() + "," + e.getY()); } public void mouseReleased(MouseEvent e){ mousetext.setText("The mouse button is up"); public void mouseEntered(MouseEvent e){ mousetext.setText("The mouse is in the applet"); public void mouseExited(MouseEvent e){ mousetext.setText("The mouse is out of the applet"); } //note that this bracket ends the applet from previous page