org.jdesktop.swingbinding.JComboBoxBinding Maven / Gradle / Ivy
/*
* Copyright (C) 2007 Sun Microsystems, Inc. All rights reserved. Use is
* subject to license terms.
*/
package org.jdesktop.swingbinding;
import javax.swing.*;
import javax.swing.event.*;
import java.util.*;
import java.util.concurrent.CopyOnWriteArrayList;
import org.jdesktop.beansbinding.AutoBinding;
import org.jdesktop.beansbinding.Property;
import org.jdesktop.beansbinding.PropertyStateEvent;
import org.jdesktop.beansbinding.PropertyStateListener;
import org.jdesktop.swingbinding.impl.AbstractColumnBinding;
import org.jdesktop.swingbinding.impl.ListBindingManager;
import static org.jdesktop.beansbinding.AutoBinding.UpdateStrategy.*;
/**
* Binds a {@code List} of objects to act as the items of a {@code JComboBox}.
* Each object in the source {@code List} is an item in the {@code JComboBox}.
* Instances of {@code JComboBoxBinding} are obtained by calling one of the
* {@code createJComboBoxBinding} methods in the {@code SwingBindings} class.
*
* Here is an example of creating a binding from a {@code List} of {@code Country}
* objects to a {@code JComboBox}:
*
*
* // create the country list
* List countries = createCountryList();
*
* // create the binding from List to JComboBox
* JComboBoxBinding cb = SwingBindings.createJComboBoxBinding(READ, countries, jComboBox);
*
* // realize the binding
* cb.bind();
*
*
* If the {@code List} is an instance of {@code ObservableList}, then changes to
* the {@code List} contents (such as adding, removing or replacing an object)
* are reflected in the {@code JComboBox}. Important: Changing the contents
* of a non-observable {@code List} while it is participating in a
* {@code JComboBoxBinding} is unsupported, resulting in undefined behavior and
* possible exceptions.
*
* {@code JComboBoxBinding} requires
* extra clarification on the operation of the
* {@code refresh} and {@code save} methods and the meaning of the update
* strategy. The target property of a {@code JComboBoxBinding} is not the
* target {@code JComboBox} property provided in the constructor, but rather a
* private synthetic property representing the {@code List} of objects to show
* in the target {@code JComboBox}. This synthetic property is readable/writeable
* only when the {@code JComboBoxBinding} is bound and the target {@code JComboBox}
* property is readable with a {@code non-null} value.
*
* It is this private synthetic property on which the {@code refresh} and
* {@code save} methods operate; meaning that these methods simply cause syncing
* between the value of the source {@code List} property and the value of the
* synthetic target property (representing the {@code List} to be shown in the
* target {@code JComboBox}). These methods do not, therefore, have anything to do
* with refreshing values in the {@code JComboBox}. Likewise, the update
* strategy, which simply controls when {@code refresh} and {@code save} are
* automatically called, also has nothing to do with refreshing values
* in the {@code JComboBox}.
*
* Note: At the current time, the {@code READ_WRITE} update strategy
* is not useful for {@code JComboBoxBinding}. To prevent unwanted confusion,
* {@code READ_WRITE} is translated to {@code READ} by {@code JComboBoxBinding's}
* constructor.
*
* {@code JComboBoxBinding} works by installing a custom model on the target
* {@code JComboBox}, as appropriate, to represent the source {@code List}. The
* model is installed on a target {@code JComboBox} with the first succesful call
* to {@code refresh} with that {@code JComboBox} as the target. Subsequent calls
* to {@code refresh} update the elements in this already-installed model.
* The model is uninstalled from a target {@code JComboBox} when either the
* {@code JComboBoxBinding} is unbound or when the target {@code JComboBox} property
* changes to no longer represent that {@code JComboBox}. Note: When the model is
* uninstalled from a {@code JComboBox}, it is replaced with a {@code DefaultComboBoxModel},
* in order to leave the {@code JComboBox} functional.
*
* Some of the above is easier to understand with an example. Let's consider
* a {@code JComboBoxBinding} ({@code binding}), with update strategy
* {@code READ}, between a property representing a {@code List} ({@code listP})
* and a property representing a {@code JComboBox} ({@code jComboBoxP}). {@code listP}
* and {@code jComboBoxP} both start off readable, referring to a {@code non-null}
* {@code List} and {@code non-null} {@code JComboBox} respectively. Let's look at
* what happens for each of a sequence of events:
*
*
* Sequence Event Result
* 1
* explicit call to {@code binding.bind()}
*
* - synthetic target property becomes readable/writeable
*
* - {@code refresh()} is called
*
* - model is installed on target {@code JComboBox}, representing list of objects
*
*
*
* 2
* {@code listP} changes to a new {@code List}
*
* - {@code refresh()} is called
*
* - model is updated with new list of objects
*
*
*
* 3
* {@code jComboBoxP} changes to a new {@code JComboBox}
*
* - model is uninstalled from old {@code JComboBox}
*
*
*
* 4
* explicit call to {@code binding.refresh()}
*
* - model is installed on target {@code JComboBox}, representing list of objects
*
*
*
* 5
* {@code listP} changes to a new {@code List}
*
* - {@code refresh()} is called
*
* - model is updated with new list of objects
*
*
*
* 6
* explicit call to {@code binding.unbind()}
*
* - model is uninstalled from target {@code JComboBox}
*
*
*
*
* Notice that in step 3, when the value
* of the {@code JComboBox} property changed, the new {@code JComboBox} did not
* automatically get the model with the elements applied to it. A change to the
* target value should not cause an {@code AutoBinding} to sync the target from
* the source. Step 4 forces a sync by explicitly calling {@code refresh}.
* Alternatively, it could be caused by any other action that results
* in a {@code refresh} (for example, the source property changing value, or an
* explicit call to {@code unbind} followed by {@code bind}).
*
* In addition to binding the items of a {@code JComboBox}, it is possible to
* bind to the selected item of a {@code JComboBox}.
* See the list of
* interesting swing properties in the package summary for more details.
*
* @param the type of elements in the source {@code List}
* @param the type of source object (on which the source property resolves to {@code List})
* @param the type of target object (on which the target property resolves to {@code JComboBox})
*
* @author Shannon Hickey
*/
public final class JComboBoxBinding extends AutoBinding, TS, List> {
private Property comboP;
private ElementsProperty elementsP;
private Handler handler = new Handler();
private JComboBox combo;
private BindingComboBoxModel model;
/**
* Constructs an instance of {@code JComboBoxBinding}.
*
* @param strategy the update strategy
* @param sourceObject the source object
* @param sourceListProperty a property on the source object that resolves to the {@code List} of elements
* @param targetObject the target object
* @param targetJComboBoxProperty a property on the target object that resolves to a {@code JComboBox}
* @param name a name for the {@code JComboBoxBinding}
* @throws IllegalArgumentException if the source property or target property is {@code null}
*/
protected JComboBoxBinding(UpdateStrategy strategy, SS sourceObject, Property> sourceListProperty, TS targetObject, Property targetJComboBoxProperty, String name) {
super(strategy == READ_WRITE ? READ : strategy,
sourceObject, sourceListProperty, targetObject, new ElementsProperty(), name);
if (targetJComboBoxProperty == null) {
throw new IllegalArgumentException("target JComboBox property can't be null");
}
comboP = targetJComboBoxProperty;
elementsP = (ElementsProperty)getTargetProperty();
}
protected void bindImpl() {
elementsP.setAccessible(isComboAccessible());
comboP.addPropertyStateListener(getTargetObject(), handler);
elementsP.addPropertyStateListener(null, handler);
super.bindImpl();
}
protected void unbindImpl() {
elementsP.removePropertyStateListener(null, handler);
comboP.removePropertyStateListener(getTargetObject(), handler);
elementsP.setAccessible(false);
cleanupForLast();
super.unbindImpl();
}
private boolean isComboAccessible() {
return comboP.isReadable(getTargetObject()) && comboP.getValue(getTargetObject()) != null;
}
private boolean isComboAccessible(Object value) {
return value != null && value != PropertyStateEvent.UNREADABLE;
}
private void cleanupForLast() {
if (combo == null) {
return;
}
combo.setSelectedItem(null);
combo.setModel(new DefaultComboBoxModel());
model.updateElements(null, combo.isEditable());
combo = null;
model = null;
}
private class Handler implements PropertyStateListener {
public void propertyStateChanged(PropertyStateEvent pse) {
if (!pse.getValueChanged()) {
return;
}
if (pse.getSourceProperty() == comboP) {
cleanupForLast();
boolean wasAccessible = isComboAccessible(pse.getOldValue());
boolean isAccessible = isComboAccessible(pse.getNewValue());
if (wasAccessible != isAccessible) {
elementsP.setAccessible(isAccessible);
} else if (elementsP.isAccessible()) {
elementsP.setValueAndIgnore(null, null);
}
} else {
if (((ElementsProperty.ElementsPropertyStateEvent)pse).shouldIgnore()) {
return;
}
if (combo == null) {
combo = comboP.getValue(getTargetObject());
combo.setSelectedItem(null);
model = new BindingComboBoxModel();
combo.setModel(model);
}
model.updateElements((List)pse.getNewValue(), combo.isEditable());
}
}
}
private final class BindingComboBoxModel extends ListBindingManager implements ComboBoxModel {
private final List listeners;
private Object selectedItem = null;
private int selectedModelIndex = -1;
public BindingComboBoxModel() {
listeners = new CopyOnWriteArrayList();
}
public void updateElements(List elements, boolean isEditable) {
setElements(elements, false);
if (!isEditable || selectedModelIndex != -1) {
selectedItem = null;
selectedModelIndex = -1;
}
if (size() <= 0) {
if (selectedModelIndex != -1) {
selectedModelIndex = -1;
selectedItem = null;
}
} else {
if (selectedItem == null) {
selectedModelIndex = 0;
selectedItem = getElementAt(selectedModelIndex);
}
}
allChanged();
}
protected AbstractColumnBinding[] getColBindings() {
return new AbstractColumnBinding[0];
}
public Object getSelectedItem() {
return selectedItem;
}
public void setSelectedItem(Object item) {
// This is what DefaultComboBoxModel does (yes, yuck!)
if ((selectedItem != null && !selectedItem.equals(item)) || selectedItem == null && item != null) {
selectedItem = item;
contentsChanged(-1, -1);
selectedModelIndex = -1;
if (item != null) {
int size = size();
for (int i = 0; i < size; i++) {
if (item.equals(getElementAt(i))) {
selectedModelIndex = i;
break;
}
}
}
}
}
protected void allChanged() {
contentsChanged(0, size());
}
protected void valueChanged(int row, int column) {
// we're not expecting any value changes since we don't have any
// detail bindings for JComboBox
}
protected void added(int index, int length) {
assert length > 0; // enforced by ListBindingManager
ListDataEvent e = new ListDataEvent(this, ListDataEvent.INTERVAL_ADDED, index, index + length - 1);
int size = listeners.size();
for (int i = size - 1; i >= 0; i--) {
listeners.get(i).intervalAdded(e);
}
if (size() == length && selectedItem == null) {
setSelectedItem(getElementAt(0));
}
}
protected void removed(int index, int length) {
assert length > 0; // enforced by ListBindingManager
ListDataEvent e = new ListDataEvent(this, ListDataEvent.INTERVAL_REMOVED, index, index + length - 1);
int size = listeners.size();
for (int i = size - 1; i >= 0; i--) {
listeners.get(i).intervalRemoved(e);
}
if (selectedModelIndex >= index && selectedModelIndex < index + length) {
if (size() == 0) {
setSelectedItem(null);
} else {
setSelectedItem(getElementAt(Math.max(index - 1, 0)));
}
}
}
protected void changed(int row) {
contentsChanged(row, row);
}
private void contentsChanged(int row0, int row1) {
ListDataEvent e = new ListDataEvent(this, ListDataEvent.CONTENTS_CHANGED, row0, row1);
int size = listeners.size();
for (int i = size - 1; i >= 0; i--) {
listeners.get(i).contentsChanged(e);
}
}
public Object getElementAt(int index) {
return getElement(index);
}
public void addListDataListener(ListDataListener l) {
listeners.add(l);
}
public void removeListDataListener(ListDataListener l) {
listeners.remove(l);
}
public int getSize() {
return size();
}
}
}