src.com.ibm.as400.vaccess.ErrorEventSupport Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of jt400 Show documentation
Show all versions of jt400 Show documentation
The Open Source version of the IBM Toolbox for Java
///////////////////////////////////////////////////////////////////////////////
//
// JTOpen (IBM Toolbox for Java - OSS version)
//
// Filename: ErrorEventSupport.java
//
// The source code contained herein is licensed under the IBM Public License
// Version 1.0, which has been approved by the Open Source Initiative.
// Copyright (C) 1997-2000 International Business Machines Corporation and
// others. All rights reserved.
//
///////////////////////////////////////////////////////////////////////////////
package com.ibm.as400.vaccess;
import java.util.Enumeration;
import java.util.Vector;
/**
The ErrorEventSupport class represents a list of
ErrorListeners. It manages the list as well as
provides notification services for ErrorEvents.
This is also an ErrorListener and will dispatch
all error events.
**/
//
// Implementation note:
//
// @A1A
// THIS APPLIES TO ALL "EVENT SUPPORT" CLASSES IN THIS PACKAGE:
//
// Class A is defined to fire ErrorEvents. As a result, it
// has to maintain a list of the listeners. Since many classes
// in the package have to do this, we provide an "event support"
// class to maintain this list. This is patterened after
// the java.beans.PropertyChangeSupport class provided in the JDK.
//
// public class A
// {
// private ErrorEventSupport eventSupport_ = new ErrorEventSupport (this);
//
// public void addErrorListener (ErrorListener listener)
// {
// eventSupport_.addErrorListener (listener);
// }
//
// public void removeErrorListener (ErrorListener listener)
// {
// eventSupport_.removeErrorListener (listener);
// }
//
// public void someMethod ()
// {
// ... some code here ...
// eventSupport_.fireObjectChanged (anObject);
// ... some more code here ...
// }
// }
//
// There is another case where class A contains a private instance
// of class B. B fires ErrorEvents, and A needs to listen
// to B and refire all ErrorEvents. In addition, it needs
// to change the source of the event so that it looks like
// A is the source, even though B is the real source. The
// reason for this is that listeners have public access to the
// source of the event, and we don't want them to have access to B.
//
// This is all easy to accompilsh by simply adding the
// event support object as a listener to B. The event
// support object takes care of the rest.
//
// public class A
// {
// private B b_;
// private ErrorEventSupport eventSupport_ = new ErrorEventSupport (this);
//
// public A ()
// {
// b_ = new B ();
// b_.addErrorListener (eventSupport_);
// }
// }
//
// This type of event dispatching happens all over in the
// vaccess package. This is because of the hierarchy of
// components. Consider an explorer pane that presents
// a view of a directory structure. Here is the hierarchy:
//
// AS400ExplorerPane
// |
// +-- AS400TreePane
// | |
// | +-- AS400TreeModel
// | |
// | +-- VIFSDirectory (root directory) <-----------+
// | | |
// | +-- VIFSDirectory (subdirectory) |
// | | | |
// | | +-- VIFSFile (file in subdirectory) |
// | | |
// | +-- VIFSFile (file in root directory) |
// | |
// +-- AS400DetailsPane |
// | |
// +-- AS400DetailsModel |
// | |
// +----------------------------------------------+
//
// If any object fires certain events, then all objects
// above them in the hierarchy need to hear about it. Rather
// than making all objects specifically listen to all objects
// below them, we just make them listen to the objects
// directly below them. Then they "bubble" (dispatch) them
// up the chain to the parent. All nodes in between can process
// them on the way up.
//
// Now, when one of the VIFSFile's catches an exception, it
// will fire an ErrorEvent up the chain, so that the top level
// frame can process it and, for example, put up an error
// dialog.
//
class ErrorEventSupport
implements ErrorListener
{
private static final String copyright = "Copyright (C) 1997-2000 International Business Machines Corporation and others.";
// Source of the events.
private Object source_ = null;
// Vector of listeners, used to add and remove listeners.
transient private Vector errorListenersV_
= new Vector();
// Array used to send the events. Is a copy of errorListenersV_,
// used for speed.
transient private ErrorListener[] errorListeners_
= new ErrorListener[0];
/**
Constructs a ErrorEventSupport object.
@param source The source of the events.
**/
public ErrorEventSupport (Object source)
{
source_ = source;
}
/**
Adds a listener.
@param listener The listener.
**/
public void addErrorListener (ErrorListener listener)
{
if (listener == null)
{
throw new NullPointerException("listener");
}
// Add new listener.
errorListenersV_.addElement(listener);
// copyInto is synchronized, so we don't have to synchronize V.
synchronized(errorListeners_)
{
errorListeners_ = new ErrorListener[errorListenersV_.size()];
errorListenersV_.copyInto(errorListeners_);
}
}
/**
Processes a error event.
@param event The event.
**/
public void errorOccurred (ErrorEvent event)
{
fireError ( event.getException() );
}
/**
Fires an ErrorEvent to listeners.
@param e The exception.
**/
void fireError(Exception e)
{
fireError (new ErrorEvent(source_, e));
}
/**
Fires an ErrorEvent to listeners.
@param event The event.
**/
void fireError(ErrorEvent event)
{
synchronized(errorListeners_)
{
for (int i=0; i© 2015 - 2025 Weber Informatics LLC | Privacy Policy