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org.eclipse.core.databinding.observable.set
Class ComputedSet
java.lang.Object
org.eclipse.core.databinding.observable.AbstractObservable
org.eclipse.core.databinding.observable.set.AbstractObservableSet
org.eclipse.core.databinding.observable.set.ComputedSet
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All Implemented Interfaces:
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Iterable,
Collection,
Set,
IObservable,
IObservableCollection,
IObservableSet
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public abstract class ComputedSet
- extends
AbstractObservableSet
A lazily calculated set that automatically computes and registers listeners
on its dependencies as long as all of its dependencies are
IObservable objects. Any change to one of the observable dependencies
causes the set to be recomputed.
This class is thread safe. All state accessing methods must be invoked from
the
current realm. Methods for adding and removing
listeners may be invoked from any thread.
Example: compute the set of all primes greater than 1 and less than the value
of an
IObservableValue <
Integer
>.
final IObservableValue max = WritableValue.withValueType(Integer.TYPE);
max.setValue(new Integer(0));
IObservableSet primes = new ComputedSet() {
protected Set calculate() {
int maxVal = ((Integer) max.getValue()).intValue();
Set result = new HashSet();
outer: for (int i = 2; i < maxVal; i++) {
for (Iterator it = result.iterator(); it.hasNext();) {
Integer knownPrime = (Integer) it.next();
if (i % knownPrime.intValue() == 0)
continue outer;
}
result.add(new Integer(i));
}
return result;
}
};
System.out.println(primes); // => "[]"
max.setValue(new Integer(20));
System.out.println(primes); // => "[2, 3, 5, 7, 11, 13, 17, 19]"
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Since:
- 1.2
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Constructor Summary
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ComputedSet
()
Creates a computed set in the default realm and with an unknown (null)
element type. |
ComputedSet
(
Object elementType)
Creates a computed set in the default realm and with the given element
type. |
ComputedSet
(
Realm realm)
Creates a computed set in given realm and with an unknown (null) element
type. |
ComputedSet
(
Realm realm,
Object elementType)
Creates a computed set in the given realm and with the given element
type. |
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Methods inherited from class org.eclipse.core.databinding.observable.set.
AbstractObservableSet
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add,
addAll,
clear,
contains,
containsAll,
equals,
fireChange,
fireSetChange,
firstListenerAdded,
getterCalled,
hashCode,
isEmpty,
iterator,
lastListenerRemoved,
remove,
removeAll,
removeSetChangeListener,
retainAll,
setStale,
size,
toArray,
toArray,
toString
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ComputedSet
public ComputedSet()
- Creates a computed set in the default realm and with an unknown (null)
element type.
ComputedSet
public ComputedSet(
Object elementType)
- Creates a computed set in the default realm and with the given element
type.
-
Parameters:
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elementType - the element type, may be null to indicate unknown
element type
ComputedSet
public ComputedSet(
Realm realm)
- Creates a computed set in given realm and with an unknown (null) element
type.
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Parameters:
-
realm - the realm
ComputedSet
public ComputedSet(
Realm realm,
Object elementType)
- Creates a computed set in the given realm and with the given element
type.
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Parameters:
-
realm - the realm -
elementType - the element type, may be null to indicate unknown
element type
doGetSize
protected int doGetSize()
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getWrappedSet
protected
Set getWrappedSet()
-
-
Specified by:
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getWrappedSet
in class
AbstractObservableSet
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calculate
protected abstract
Set calculate()
- Subclasses must override this method to calculate the set contents. Any
dependencies used to calculate the set must be
IObservable, and
implementers must use one of the interface methods tagged TrackedGetter
for ComputedSet to recognize it as a dependency.
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Returns:
- the object's set.
isStale
public boolean isStale()
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Description copied from interface:
IObservable
- Returns whether the state of this observable is stale and is expected to
change soon. A non-stale observable that becomes stale will notify its
stale listeners. A stale object that becomes non-stale does so by
changing its state and notifying its change listeners, it does not
notify its stale listeners about becoming non-stale. Clients that do not
expect asynchronous changes may ignore staleness of observable objects.
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Specified by:
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isStale
in interface
IObservable
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Overrides:
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isStale
in class
AbstractObservableSet
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Returns:
- Returns the stale state.
getElementType
public
Object getElementType()
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Description copied from interface:
IObservableCollection
- Returns the element type of this observable collection, or
null if this observable collection is untyped.
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Returns:
- the element type or
null if untyped
addChangeListener
public void addChangeListener(
IChangeListener listener)
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Description copied from interface:
IObservable
- Adds the given change listener to the list of change listeners. Change
listeners are notified about changes of the state of this observable in a
generic way, without specifying the change that happened. To get the
changed state, a change listener needs to query for the current state of
this observable.
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Specified by:
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addChangeListener
in interface
IObservable
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Overrides:
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addChangeListener
in class
AbstractObservable
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addSetChangeListener
public void addSetChangeListener(
ISetChangeListener listener)
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Specified by:
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addSetChangeListener
in interface
IObservableSet
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Overrides:
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addSetChangeListener
in class
AbstractObservableSet
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dispose
public void dispose()
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Description copied from interface:
IObservable
- Disposes of this observable object, removing all listeners registered
with this object, and all listeners this object might have registered on
other objects.
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Specified by:
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dispose
in interface
IObservable
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Overrides:
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dispose
in class
AbstractObservable
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addListener
protected void addListener(
Object listenerType,
IObservablesListener listener)
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Parameters:
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listenerType - -
listener -
removeListener
protected void removeListener(
Object listenerType,
IObservablesListener listener)
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Parameters:
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listenerType - -
listener -
hasListeners
protected boolean hasListeners()
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fireEvent
protected void fireEvent(
ObservableEvent event)
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getRealm
public
Realm getRealm()
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Returns:
- Returns the realm.
clone
protected
Object clone()
throws
CloneNotSupportedException
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Overrides:
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clone
in class
Object
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Throws:
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CloneNotSupportedException
Guidelines for using Eclipse APIs.
Copyright (c) Eclipse contributors and others 2000, 2008. All rights reserved.
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