vgp.tutor.updatePanel
Class MyClass_IP

java.lang.Object
  |
  +--java.awt.Component
        |
        +--java.awt.Container
              |
              +--java.awt.Panel
                    |
                    +--jv.object.PsPanel
                          |
                          +--vgp.tutor.updatePanel.MyClass_IP

All Implemented Interfaces:

javax.accessibility.Accessible, java.awt.event.ActionListener, java.util.EventListener, java.awt.image.ImageObserver, java.awt.event.ItemListener, java.awt.MenuContainer, PsUpdateIf, java.io.Serializable, java.awt.event.TextListener

public class MyClass_IP

extends PsPanel

implements java.awt.event.ActionListener, java.awt.event.ItemListener, java.awt.event.TextListener

Tutorial info panel for combined use of Java1.1 Events and JavaView Update Mechanism.

In the Java 1.1 event mechanism each widget may have registered listeners which are informed whenever the state of a widget chances. Java distinguishes between different types of events such as ActionEvent or ItemEvent, and listeners may register for a single or multiple events. Each listener must implement an interface corresponding to a specific event. This tutorial panel is both, an ActionListener and an ItemListener, and is able to register itself in widgets.

The JavaView update mechnism forces panels to have a single parent. The parent registers itself using the method 'setParent' of the panel. Whenever the panel changes and its methods 'actionPerformed()' or 'itemStateChanged()' are called, it modifies the instance variables of the parent directly but must invoke the update method of its parent such that the parent initiate further recomputations of itself and its dependents.

The strong coupling of a panel and its parent also allows the parent to inform the panel whenever the parent has changed. This is accomplished through the update method of the panel. This method should only be called from the parent and its superclasses and, usually, not from inside the panel.

Version:

15.08.99, 1.10 revised (kp) Converted to AWT1.1 event model.
15.08.99, 1.00 created (kp)

Author:

Konrad Polthier

See Also:

PsObject, PsUpdateIf, Serialized Form

Fields inherited from class jv.object.PsPanel

BORDER_GROOVE, BORDER_LINE, BORDER_NONE, BORDER_SUNK

Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT

Fields inherited from interface java.awt.image.ImageObserver

ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

Constructor Summary

MyClass_IP()
Create and layout the widgets of the panel.

Method Summary

void	actionPerformed(java.awt.event.ActionEvent event) Handle action events invoked from buttons, menu items, text fields.
void	init() Set values of variables.
void	itemStateChanged(java.awt.event.ItemEvent event) Handle item state events invoked from choices, checkboxes, list items.
void	setParent(PsUpdateIf parent) Set parent of panel which supplies the data inspected by the panel.
void	textValueChanged(java.awt.event.TextEvent event) Handle any chances in text field.
boolean	update(java.lang.Object event) Update the panel whenever the parent has changed somewhere else.

Methods inherited from class jv.object.PsPanel

addLabelComponent, addLine, addSubTitle, addTextField, addTitle, drawBorder, drawBorder, drawText, getFather, getInsets, getLanguage, getTitle, hasTitle, instanceOf, paint, setBorderType, setImage, setInsetSize, setOutOfDate, setTitle, setVisible, update

Methods inherited from class java.awt.Panel

addNotify, getAccessibleContext

Methods inherited from class java.awt.Container

add, add, add, add, add, addContainerListener, countComponents, deliverEvent, doLayout, findComponentAt, findComponentAt, getAlignmentX, getAlignmentY, getComponent, getComponentAt, getComponentAt, getComponentCount, getComponents, getLayout, getListeners, getMaximumSize, getMinimumSize, getPreferredSize, insets, invalidate, isAncestorOf, layout, list, list, locate, minimumSize, paintComponents, preferredSize, print, printComponents, remove, remove, removeAll, removeContainerListener, removeNotify, setFont, setLayout, validate

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addPropertyChangeListener, addPropertyChangeListener, bounds, checkImage, checkImage, contains, contains, createImage, createImage, disable, dispatchEvent, enable, enable, enableInputMethods, getBackground, getBounds, getBounds, getColorModel, getComponentOrientation, getCursor, getDropTarget, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getInputContext, getInputMethodRequests, getLocale, getLocation, getLocation, getLocationOnScreen, getName, getParent, getPeer, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, isDisplayable, isDoubleBuffered, isEnabled, isFocusTraversable, isLightweight, isOpaque, isShowing, isValid, isVisible, keyDown, keyUp, list, list, list, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, postEvent, prepareImage, prepareImage, printAll, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setForeground, setLocale, setLocation, setLocation, setName, setSize, setSize, show, show, size, toString, transferFocus

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface jv.object.PsUpdateIf

getName

Constructor Detail

MyClass_IP

public MyClass_IP()

Create and layout the widgets of the panel.

Method Detail

init

public void init()

Set values of variables. Method is also used to reset the panel.

Overrides:

init in class PsPanel

setParent

public void setParent(PsUpdateIf parent)

Set parent of panel which supplies the data inspected by the panel.

Overrides:

setParent in class PsPanel

Following copied from interface: jv.object.PsUpdateIf

Parameters:

aParent - will receive events which this does not handle

See Also:

PsUpdateIf.getFather(), PsUpdateIf.update(Object)

update

public boolean update(java.lang.Object event)

Update the panel whenever the parent has changed somewhere else. Method is invoked from the parent or its superclasses.

Overrides:

update in class PsPanel

Following copied from interface: jv.object.PsUpdateIf

Parameters:

event - carries a lot of information

Returns:

true if event has been handled, otherwise false

See Also:

PsObject, PsUpdateIf.getFather(), PsUpdateIf.setParent(PsUpdateIf)

actionPerformed

public void actionPerformed(java.awt.event.ActionEvent event)

Handle action events invoked from buttons, menu items, text fields.

Specified by:

actionPerformed in interface java.awt.event.ActionListener

itemStateChanged

public void itemStateChanged(java.awt.event.ItemEvent event)

Handle item state events invoked from choices, checkboxes, list items.

Specified by:

itemStateChanged in interface java.awt.event.ItemListener

textValueChanged

public void textValueChanged(java.awt.event.TextEvent event)

Handle any chances in text field. After any keystroke an event is sent, therefore, catching these events frees the user from pressing .

Specified by:

textValueChanged in interface java.awt.event.TextListener