javafx.beans.binding.ListBinding Maven / Gradle / Ivy
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package javafx.beans.binding;
import com.sun.javafx.binding.BindingHelperObserver;
import com.sun.javafx.binding.ListExpressionHelper;
import javafx.beans.InvalidationListener;
import javafx.beans.Observable;
import javafx.beans.property.ReadOnlyBooleanProperty;
import javafx.beans.property.ReadOnlyBooleanPropertyBase;
import javafx.beans.property.ReadOnlyIntegerProperty;
import javafx.beans.property.ReadOnlyIntegerPropertyBase;
import javafx.beans.value.ChangeListener;
import javafx.collections.FXCollections;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;
/**
* Base class that provides most of the functionality needed to implement a
* {@link Binding} of an {@link javafx.collections.ObservableList}.
*
* {@code ListBinding} provides a simple invalidation-scheme. An extending
* class can register dependencies by calling {@link #bind(Observable...)}.
* If one of the registered dependencies becomes invalid, this
* {@code ListBinding} is marked as invalid. With
* {@link #unbind(Observable...)} listening to dependencies can be stopped.
*
* To provide a concrete implementation of this class, the method
* {@link #computeValue()} has to be implemented to calculate the value of this
* binding based on the current state of the dependencies. It is called when
* {@link #get()} is called for an invalid binding.
*
* See {@link DoubleBinding} for an example how this base class can be extended.
*
* @see Binding
* @see ListExpression
*
* @param
* the type of the {@code List} element
* @since JavaFX 2.1
*/
public abstract class ListBinding extends ListExpression implements Binding> {
/**
* Creates a default {@code ListBinding}.
*/
public ListBinding() {
}
private final ListChangeListener listChangeListener = new ListChangeListener() {
@Override
public void onChanged(Change change) {
invalidateProperties();
onInvalidating();
ListExpressionHelper.fireValueChangedEvent(helper, change);
}
};
private ObservableList value;
private boolean valid = false;
private BindingHelperObserver observer;
private ListExpressionHelper helper = null;
private SizeProperty size0;
private EmptyProperty empty0;
@Override
public ReadOnlyIntegerProperty sizeProperty() {
if (size0 == null) {
size0 = new SizeProperty();
}
return size0;
}
private class SizeProperty extends ReadOnlyIntegerPropertyBase {
@Override
public int get() {
return size();
}
@Override
public Object getBean() {
return ListBinding.this;
}
@Override
public String getName() {
return "size";
}
protected void fireValueChangedEvent() {
super.fireValueChangedEvent();
}
}
@Override
public ReadOnlyBooleanProperty emptyProperty() {
if (empty0 == null) {
empty0 = new EmptyProperty();
}
return empty0;
}
private class EmptyProperty extends ReadOnlyBooleanPropertyBase {
@Override
public boolean get() {
return isEmpty();
}
@Override
public Object getBean() {
return ListBinding.this;
}
@Override
public String getName() {
return "empty";
}
protected void fireValueChangedEvent() {
super.fireValueChangedEvent();
}
}
@Override
public void addListener(InvalidationListener listener) {
helper = ListExpressionHelper.addListener(helper, this, listener);
}
@Override
public void removeListener(InvalidationListener listener) {
helper = ListExpressionHelper.removeListener(helper, listener);
}
@Override
public void addListener(ChangeListener> listener) {
helper = ListExpressionHelper.addListener(helper, this, listener);
}
@Override
public void removeListener(ChangeListener> listener) {
helper = ListExpressionHelper.removeListener(helper, listener);
}
@Override
public void addListener(ListChangeListener listener) {
helper = ListExpressionHelper.addListener(helper, this, listener);
}
@Override
public void removeListener(ListChangeListener listener) {
helper = ListExpressionHelper.removeListener(helper, listener);
}
/**
* Start observing the dependencies for changes. If the value of one of the
* dependencies changes, the binding is marked as invalid.
*
* @param dependencies
* the dependencies to observe
*/
protected final void bind(Observable... dependencies) {
if ((dependencies != null) && (dependencies.length > 0)) {
if (observer == null) {
observer = new BindingHelperObserver(this);
}
for (final Observable dep : dependencies) {
if (dep != null) {
dep.addListener(observer);
}
}
}
}
/**
* Stop observing the dependencies for changes.
*
* @param dependencies
* the dependencies to stop observing
*/
protected final void unbind(Observable... dependencies) {
if (observer != null) {
for (final Observable dep : dependencies) {
if (dep != null) {
dep.removeListener(observer);
}
}
observer = null;
}
}
/**
* A default implementation of {@code dispose()} that is empty.
*/
@Override
public void dispose() {
}
/**
* A default implementation of {@code getDependencies()} that returns an
* empty {@link javafx.collections.ObservableList}.
*
* @return an empty {@code ObservableList}
*/
@Override
public ObservableList getDependencies() {
return FXCollections.emptyObservableList();
}
/**
* Returns the result of {@link #computeValue()}. The method
* {@code computeValue()} is only called if the binding is invalid. The
* result is cached and returned if the binding did not become invalid since
* the last call of {@code get()}.
*
* @return the current value
*/
@Override
public final ObservableList get() {
if (!valid) {
value = computeValue();
valid = true;
if (value != null) {
value.addListener(listChangeListener);
}
}
return value;
}
/**
* The method onInvalidating() can be overridden by extending classes to
* react, if this binding becomes invalid. The default implementation is
* empty.
*/
protected void onInvalidating() {
}
private void invalidateProperties() {
if (size0 != null) {
size0.fireValueChangedEvent();
}
if (empty0 != null) {
empty0.fireValueChangedEvent();
}
}
@Override
public final void invalidate() {
if (valid) {
if (value != null) {
value.removeListener(listChangeListener);
}
valid = false;
invalidateProperties();
onInvalidating();
ListExpressionHelper.fireValueChangedEvent(helper);
}
}
@Override
public final boolean isValid() {
return valid;
}
/**
* Calculates the current value of this binding.
*
* Classes extending {@code ListBinding} have to provide an implementation
* of {@code computeValue}.
*
* @return the current value
*/
protected abstract ObservableList computeValue();
/**
* Returns a string representation of this {@code ListBinding} object.
* @return a string representation of this {@code ListBinding} object.
*/
@Override
public String toString() {
return valid ? "ListBinding [value: " + get() + "]"
: "ListBinding [invalid]";
}
}