Home » Eclipse Projects » Eclipse Platform » ObservabelList question and databinding
| ObservabelList question and databinding [message #325595] |
Fri, 22 February 2008 15:06  |
Eclipse User |
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Originally posted by: joelgreg.yahoo.com
Hi there,
I've been playing with Observables for a while and I'm wondering if I'm
missing something. Is it possible to detect a change in one of the items
within an ObservableList?? I can surely detect additions and removals but
I can't detect a change of an item.
In the following snippet, 2 lists are bound together, I make a change to
one and the second gets updated. Good. However the list change event is
not fired. Do I need to register a listener for every item in the list? It
has to be simple.
Any help is appreciated.
Thanks, JG
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import org.eclipse.core.databinding.DataBindingContext;
import org.eclipse.core.databinding.observable.AbstractObservable;
import org.eclipse.core.databinding.observable.ChangeEvent;
import org.eclipse.core.databinding.observable.IChangeListener;
import org.eclipse.core.databinding.observable.Realm;
import org.eclipse.core.databinding.observable.list.IListChangeList ener;
import org.eclipse.core.databinding.observable.list.IObservableList ;
import org.eclipse.core.databinding.observable.list.ListChangeEvent ;
import org.eclipse.core.databinding.observable.list.WritableList;
import org.eclipse.jface.databinding.swt.SWTObservables;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
public class Test
{
public static void main(String[] args)
{
final Display display = new Display();
Realm.runWithDefault(SWTObservables.getRealm(display), new Runnable()
{
public void run()
{
Shell shell = new View().createShell();
}
});
}
public static abstract class AbstractModelObject extends
AbstractObservable
{
public AbstractModelObject()
{
super( Realm.getDefault() );
}
private PropertyChangeSupport propertyChangeSupport = new
PropertyChangeSupport(this);
public void addPropertyChangeListener(PropertyChangeListener listener)
{
propertyChangeSupport.addPropertyChangeListener(listener);
}
public void addPropertyChangeListener(String propertyName,
PropertyChangeListener listener)
{
propertyChangeSupport.addPropertyChangeListener(propertyName , listener);
}
public void removePropertyChangeListener(PropertyChangeListener listener)
{
propertyChangeSupport.removePropertyChangeListener(listener) ;
}
public void removePropertyChangeListener(String propertyName,
PropertyChangeListener listener)
{
propertyChangeSupport.removePropertyChangeListener(propertyN ame,
listener);
}
protected void firePropertyChange(String propertyName, Object
oldValue, Object newValue)
{
propertyChangeSupport.firePropertyChange(propertyName, oldValue,
newValue);
}
public boolean isStale()
{
return false;
}
}
private static class Month
{
private String name;
public Month(String name)
{
this.name = name;
}
public String getName()
{
return name;
}
public String toString()
{
return "month:" + name;
}
}
static class Person extends AbstractModelObject
{
String name = "John Smith";
Month month = null;
public Person(String name, Month month)
{
this.name = name;
this.month = month;
}
public String getName()
{
return name;
}
public void setName( String name )
{
String oldValue = this.name;
this.name = name;
firePropertyChange("name", oldValue, name);
}
public Month getMonth()
{
return month;
}
public void setMonth( Month month )
{
Month oldValue = this.month;
this.month = month;
firePropertyChange( "month", oldValue, month );
}
public String toString()
{
return "[Person] name:" + name + ", " + month.toString();
}
}
static class View
{
public Shell createShell()
{
Display display = Display.getDefault();
Shell shell = new Shell(display);
DataBindingContext bindingContext = new DataBindingContext();
shell.setLayout( new FillLayout(SWT.VERTICAL) );
bindGUI(bindingContext);
shell.open();
return shell;
}
protected void bindGUI(DataBindingContext bindingContext)
{
IObservableList sourceObservableList = new WritableList();
IObservableList targetObservableList = new WritableList();
Person stephane = new Person( "Brad", new Month("23") );
Person sylvain = new Person( "Rod", new Month("18") );
Person marc = new Person( "Jack", new Month("8") );
sourceObservableList.add( stephane );
sourceObservableList.add( sylvain );
sourceObservableList.add( marc );
bindingContext.bindList ( targetObservableList,
sourceObservableList,
null,
null );
targetObservableList.addListChangeListener( new ListChangeListener() );
targetObservableList.addChangeListener( new ChangeListener() );
stephane.setMonth( new Month("50") );
System.out.println( targetObservableList );
}
class ListChangeListener implements IListChangeListener
{
public void handleListChange( ListChangeEvent event )
{
System.out.println("List change!");
}
}
class ChangeListener implements IChangeListener
{
public void handleChange( ChangeEvent event )
{
System.out.println("Change!");
}
}
}
}
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| Re: [DataBinding] ObservabelList question and databinding [message #325599 is a reply to message #325595] |
Fri, 22 February 2008 17:52  |
| Eclipse User |
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When you call IObservableList.set(int index, Object), the list change
event will represent the replacement as a removal of the old value and
an addition of the new value. For example:
Object oldValue = list.set(5, newValue);
will fire a list change event with the following entries in the diff:
{ ListDiffEntry(5, false, oldValue), ListDiffEntry(5, true, newValue) }
Another option if you're using DataBinding from CVS HEAD is to use the
new ListDiff.accept(ListDiffVisitor) method. ListDiff has methods
handleAdd, handleRemove, handleReplace, and handleMove. The accept
method iterates through the entries in the diff and calls the
appropriate method on the visitor for each semantic change.
I will be away from my newsgroup reader, so if you need further help
feel free to CC your response to my e-mail address.
Hope this helps,
Matthew
Joel Gregoire wrote:
> Hi there,
>
> I've been playing with Observables for a while and I'm wondering if I'm
> missing something. Is it possible to detect a change in one of the items
> within an ObservableList?? I can surely detect additions and removals
> but I can't detect a change of an item.
>
> In the following snippet, 2 lists are bound together, I make a change to
> one and the second gets updated. Good. However the list change event is
> not fired. Do I need to register a listener for every item in the list?
> It has to be simple.
>
> Any help is appreciated.
>
> Thanks, JG
>
> import java.beans.PropertyChangeListener;
> import java.beans.PropertyChangeSupport;
>
> import org.eclipse.core.databinding.DataBindingContext;
> import org.eclipse.core.databinding.observable.AbstractObservable;
> import org.eclipse.core.databinding.observable.ChangeEvent;
> import org.eclipse.core.databinding.observable.IChangeListener;
> import org.eclipse.core.databinding.observable.Realm;
> import org.eclipse.core.databinding.observable.list.IListChangeList ener;
> import org.eclipse.core.databinding.observable.list.IObservableList ;
> import org.eclipse.core.databinding.observable.list.ListChangeEvent ;
> import org.eclipse.core.databinding.observable.list.WritableList;
> import org.eclipse.jface.databinding.swt.SWTObservables;
> import org.eclipse.swt.SWT;
> import org.eclipse.swt.layout.FillLayout;
> import org.eclipse.swt.widgets.Display;
> import org.eclipse.swt.widgets.Shell;
>
> public class Test {
> public static void main(String[] args) {
> final Display display = new Display();
> Realm.runWithDefault(SWTObservables.getRealm(display), new
> Runnable() {
> public void run() {
> Shell shell = new View().createShell();
> }
> });
> }
>
> public static abstract class AbstractModelObject extends
> AbstractObservable
> {
> public AbstractModelObject()
> {
> super( Realm.getDefault() );
> }
>
> private PropertyChangeSupport propertyChangeSupport = new
> PropertyChangeSupport(this);
>
> public void addPropertyChangeListener(PropertyChangeListener
> listener)
> {
> propertyChangeSupport.addPropertyChangeListener(listener);
> }
>
> public void addPropertyChangeListener(String propertyName,
> PropertyChangeListener listener) {
>
> propertyChangeSupport.addPropertyChangeListener(propertyName , listener);
> }
>
> public void removePropertyChangeListener(PropertyChangeListener
> listener)
> {
> propertyChangeSupport.removePropertyChangeListener(listener) ;
> }
>
> public void removePropertyChangeListener(String propertyName,
> PropertyChangeListener listener)
> {
>
> propertyChangeSupport.removePropertyChangeListener(propertyN ame, listener);
> }
>
> protected void firePropertyChange(String propertyName, Object
> oldValue, Object newValue) {
> propertyChangeSupport.firePropertyChange(propertyName,
> oldValue, newValue);
> }
>
> public boolean isStale()
> {
> return false;
> }
> }
>
> private static class Month {
> private String name;
>
> public Month(String name) {
> this.name = name;
> }
>
> public String getName() {
> return name;
> }
>
> public String toString()
> {
> return "month:" + name;
> }
> }
>
> static class Person extends AbstractModelObject {
> String name = "John Smith";
> Month month = null;
>
> public Person(String name, Month month) {
> this.name = name;
> this.month = month;
> }
>
> public String getName() {
> return name;
> }
>
> public void setName( String name ) {
> String oldValue = this.name;
> this.name = name;
> firePropertyChange("name", oldValue, name);
> }
>
> public Month getMonth() {
> return month;
> }
>
> public void setMonth( Month month ) {
> Month oldValue = this.month;
> this.month = month;
> firePropertyChange( "month", oldValue, month );
> }
>
> public String toString()
> {
> return "[Person] name:" + name + ", " + month.toString();
> }
> }
>
> static class View {
> public Shell createShell() {
> Display display = Display.getDefault();
> Shell shell = new Shell(display);
> DataBindingContext bindingContext = new
> DataBindingContext();
>
> shell.setLayout( new FillLayout(SWT.VERTICAL) );
>
> bindGUI(bindingContext);
>
> shell.open();
> return shell;
> }
>
> protected void bindGUI(DataBindingContext bindingContext)
> {
> IObservableList sourceObservableList = new WritableList();
> IObservableList targetObservableList = new WritableList();
>
> Person stephane = new Person( "Brad", new Month("23") );
> Person sylvain = new Person( "Rod", new Month("18") );
> Person marc = new Person( "Jack", new Month("8") );
>
> sourceObservableList.add( stephane );
> sourceObservableList.add( sylvain );
> sourceObservableList.add( marc );
>
> bindingContext.bindList ( targetObservableList,
> sourceObservableList,
> null,
> null );
>
> targetObservableList.addListChangeListener( new
> ListChangeListener() );
> targetObservableList.addChangeListener( new ChangeListener() );
>
> stephane.setMonth( new Month("50") );
>
> System.out.println( targetObservableList );
> }
>
> class ListChangeListener implements IListChangeListener
> {
> public void handleListChange( ListChangeEvent event )
> {
> System.out.println("List change!");
> }
> }
>
> class ChangeListener implements IChangeListener
> {
> public void handleChange( ChangeEvent event )
> {
> System.out.println("Change!");
> }
> }
> }
> }
>
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| Re: ObservabelList question and databinding [message #325617 is a reply to message #325595] |
Fri, 22 February 2008 23:10 |
| Eclipse User |
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"Joel Gregoire" <joelgreg@yahoo.com> wrote in message
news:eab73a79d102c7a08d3d51168fdca717$1@www.eclipse.org...
> I've been playing with Observables for a while and I'm wondering if I'm
> missing something. Is it possible to detect a change in one of the items
> within an ObservableList?? I can surely detect additions and removals but
> I can't detect a change of an item.
> targetObservableList.addListChangeListener( new ListChangeListener() );
>stephane.setMonth( new Month("50") );
An observable list only notifies about changes to itself (the list), not
about changes to objects contained in the list. You could try the following:
IObservableSet targetAsSet = new ListToSetAdapter(targetObservableList);
IObservableMap monthMap = BeansObservables.observeMap(targetAsSet,
Person.class, "month");
monthMap.addMapChangeListener(new IMapChangeListener(){
public void handleMapChange(MapChangeEvent event) {
for(Iterator it = event.diff.getChangedKeys().iterator();
it.hasNext(); ) {
Object key = it.next();
System.out.println("changed month of " + key + " from " +
event.diff.getOldValue(key) + " to " + event.diff.getNewValue(key));
}
}
});
Boris
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