Download Java Windows

Java the UML Way
http://www.tisip.no/JavaTheUmlWay/
Texts, Choices and Windows
Focus listeners
Text components
Giving the user the coice between alternatives
Choices using check boxes
Choices using radio buttons
Choices using lists
Java Windows
The class tree with the windows classes
Creating a window
The differences between applets and applications
Other ways programming listeners
versjon 2002-04-17
page 2
page 3-6
page 7-9
page 10
page 11
page 12-13
page 14
page 15
page 16-18
page 19-20
page 21-22
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14
Focus Listeners
• A focus event occurs when a component gains or loses focus.
• Useful if, for example, we want to control input immediately after the
user leaves an input field. If input is not ok, the focus may be set back
to the field again (requestFocus()).
• A class describing focus listeners must implement the
java.event.FocusListener interface:
– public void focusGained()
– public void focusLost()
• Often one of the methods is empty.
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 2
Text Components
•
Object
–
–
–
Component
•
JComponent
–
–
–
JTextComponent
JTextField
JPasswordField
•
public String getText()
public void setText(String text)
public void setEditable(boolean open)
The javax.swing.JTextField class
–
–
–
–
–
Container
JTextArea
The javax.swing.text.JTextComponent class
public JTextField()
public JTextField(String text)
public JTextField(int noOfColumns)
public JTextField(String text, int noOfColumns)
public void setHorizontalAlignment(
int horizontalAdjusting)
public int getHorizontalAlignment()
public void setFont(Font newFont)
public void addActionListener(
ActionListener aListener)
The javax.swing.JPasswordField class
–
–
–
–
public JPasswordField()
public JPasswordField(int noOfColumns)
public char[] getText()
public String getText() (deprecated! )
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 3
An Example
First:
Username, password and some text are entered:
Pushing the print button gives the following text at the console:
Here is the text:
Ok, now I am here, and allowed to enter text. You are allowed to
enter text here, if you input the correct password.
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 4
Message Exchange
username
Field
password
Field
textArea
thePassword
Listener
printButton
enter ”test”
shift focus
enter ”test”
shift focus
focusLost()
okPassword()
setEnabled(true)
setEditable(true)
requestFocus()
edit the text
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 5
Show program listing 14.1, pp. 418-420
Solve the problem, page 423.
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 6
Giving the User a Choice Between Alternatives
check boxes
list
radio buttons
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 7
GUI Componenter for Choices
GUI component
Class
Listener will implement
the interface
Check box
javax.swing.JCheckBox
java.awt.ActionListener
Radio button
javax.swing.JRadioButton,
usually placed in a
javax.swing.ButtonGroup
java.awt.ActionListener
List
javax.swing.JList,
usually placed in a
javax.swing.JScrollPane
javax.swing.event.
ListSelectionListener
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 8
GUI Components for Choices
Object
ButtonGroup
Component
Container
JComponent
JList
AbstractButton
JToggleButton
JCheckBox
JRadioButton
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 9
Choices Using Check Boxes
Show program listing 14.2
pp. 426-427.
The user first clicks on the dinner check box, then on the lunch check box.
An ActionEvent is generated for every click.
Will have dinner.
The console:
Will have dinner.
Will have lunch.
Output after click
on the dinner box
Output after click
on the lunch box
Solve the problems, page 428.
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 10
Choices Using Radio Buttons
Show program listing 14.3 page 429-430.
Solve all problems, page 431.
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 11
Choices Using Lists
List with fixed contents.
Show program listing 14.4 page 432-433.
The list can be set up such that the user
can select only one item,
an interval of items,
or several intervals of items.
Solve problem 1, page 439.
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 12
Choices Using Lists
Clicking on the line
with “Evy Wilde” gives:
List with dynamic contents.
•
•
•
•
The changes have to be done in the list’s ”model”.
”The model” represents the data that will be
displayed.
”The model” is described in the DefaultListModel
class.
The contents of the list displayed are described in
the JList class.
Show program listing 14.5, p. 436-437.
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Solve problem 2, page 439.
Chapter 14, page 13
Java Windows
Primary Window (the JFrame class) with
buttons for minimizing, maximizing, and closing,
and with a title bar.
Secondary Window
or Dialog
(the JDialog class),
will be closed if
the parent window
is closed
Internal Windows (the JInternalFrame class) with
buttons for minimizing, maximizing, and closing.
An internal window is clipped when displayed
if its extension is outside the primary window’s boundaries.
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 14
The Class Tree for the Windows Classes
Object
Component
Container
JComponent
JInternalFrame
Window
JWindow
Panel
Frame
Dialog
Applet
JFrame
JDialog
JApplet
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 15
Creating a Windows
import javax.swing.JFrame;
class TestJFrame {
public static void main(String[] args) {
JFrame myFirstWindow = new JFrame("My First Window");
myFirstWindow.setVisible(true);
myFirstWindow.setSize(300, 200); // the size in pixels
}
} // this program does not work correctly
• The window is closed, but the Java interpreter keeps running…
• The Java interpreter may be stopped by using System.exit(0);, but
where should this statement be inserted?
• We have to create an object, listening to the window closing event.
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 16
The WindowListener Interface and
the WindowAdapter Class
•
The java.awt.event.WindowListener interface:
void windowActivated(WindowEvent event);
void windowClosed(WindowEvent event);
void windowClosing(WindowEvent event);
void windowDeactivated(WindowEvent event);
void windowDeiconified(WindowEvent event);
void windowIconified(WindowEvent event);
void windowOpened(WindowEvent event);
•
Often all these methods, except for one, have empty bodies, therefore there
exists an adapter class (this is true for all awt listener interfaces with more than
one method):
package java.awt.event;
public abstract class WindowAdapter implements WindowListener {
public void windowOpened(WindowEvent event) {}
public void windowClosing(WindowEvent event) {}
// ... and so on, only empty bodies
}
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 17
An Example Using the Adapter Class
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
class JFrame2 extends JFrame {
public JFrame2() {
Container guiContainer = getContentPane();
guiContainer.setLayout(new FlowLayout());
guiContainer.add(new JLabel("This window handles closing. Close the window!"));
addWindowListener(new MyWindowListener());
}
private class MyWindowListener extends WindowAdapter {
public void windowClosing(WindowEvent event) {
System.out.println("Here we may write to data files, etc.");
System.exit(0); // Remember this!
}
}
}
class TestJFrame2 {
public static void main(String[] args) {
Solve problems
JFrame mySecondWindow = new JFrame2();
mySecondWindow.setTitle("My Second Window");
mySecondWindow.setSize(400, 100);
mySecondWindow.setVisible(true);
}
}
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
2 and 3, page 446.
Chapter 14, page 18
Differences Between Applets and Applications
• The applet
–
–
–
–
The applet is a subclass of JApplet.
The applet class must have public access.
The user interface is constructed in the init() method.
The browser instantiates the applet object and sends the init() message to
it.
• The application
–
–
–
–
The application is a subclass of JFrame.
Most of our applications have package access.
The user interface is constructed in the constructor.
The instantiation of application objects is coded in our programs, for
example in the main() method.
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 19
class ColorButtonApplication extends JFrame {
private Container guiContainer;
public ColorButtonApplication(String title) {
super(title);
guiContainer = getContentPane();
guiContainer.setLayout(new FlowLayout());
JButton myButton = new JButton("Push here!!");
guiContainer.add(myButton);
public class ColorButtonApplet2 extends JApplet {
ButtonListener theButtonListener =
private Container guiContainer;
new ButtonListener();
myButton.addActionListener(theButtonListener);
public void init() {
}
guiContainer = getContentPane();
private class ButtonListener
guiContainer.setLayout(new FlowLayout());
implements ActionListener {
JButton myButton = new JButton("Push here!!");
public void actionPerformed(ActionEvent event) {
guiContainer.add(myButton);
guiContainer.setBackground(Color.red);
ButtonListener theButtonListener = new ButtonListener();
}
myButton.addActionListener(theButtonListener);
}
}
}
class TestColorButtonApplication {
private class ButtonListener implements ActionListener {
public static void main(String[] args) {
public void actionPerformed(ActionEvent event) {
ColorButtonApplication myWindow
guiContainer.setBackground(Color.red);
= new ColorButtonApplication("My Window");
}
myWindow.pack();
}
myWindow.setVisible(true);
}
myWindow.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE);
}
}
Differences Between Applets
and Applications, an Example
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 20
Other Ways to Program Listeners:
1. The Window as Listener
public class ColorButtonAppletThis extends JApplet implements ActionListener {
private Container guiContainer;
The class describing the applet,
public void init() {
is the same as the class
guiContainer = getContentPane();
implementing the ActionListener
guiContainer.setLayout(new FlowLayout());
interface
JButton myButton = new JButton("Push here!!");
guiContainer.add(myButton);
this is registered as a
myButton.addActionListener(this);
listener object
}
public void actionPerformed(ActionEvent event) {
guiContainer.setBackground(Color.red);
}
The inner class
}
ButtonListener is gone.
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 21
Other Ways to Program Listeners:
2. An Anonymous Class
new tells us that an object is to
be instantiated
Here are the parentheses enclosing
the argument to the
addActionListener method.
The class which the object will be an instance of is
unnamed. It is anonymous. The class will be an
implementation of a listener interface, or it will be a
subclass of an adapter class. The name of the
interface or the adapter class has to be stated
here.
myButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
guiBeholder.setBackground(Color.red);
}
} );
This semicolon terminates the
myButton.add.... statement.
These curly braces enclose
the anonymous class.
Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal.
ISBN 0-470-84386-1, John Wiley & Sons Ltd 2002
The Research Foundation TISIP, http://tisip.no/engelsk/
Chapter 14, page 22