org.dellroad.stuff.vaadin7.ReadOnlyProperty Maven / Gradle / Ivy
Show all versions of dellroad-stuff-vaadin7 Show documentation
/*
* Copyright (C) 2022 Archie L. Cobbs. All rights reserved.
*/
package org.dellroad.stuff.vaadin7;
import com.vaadin.data.Property;
import java.util.EventObject;
/**
* Support superclass for {@link Property}s with read-only values.
* Provides a somewhat more space-efficient implementation than Vaadin's {@link com.vaadin.data.util.AbstractProperty},
* which is useful when there are many instances in memory.
*
* @param the type of the property
*/
@SuppressWarnings({ "serial", "deprecation" })
public abstract class ReadOnlyProperty implements
Property, Property.ValueChangeNotifier, Property.ReadOnlyStatusChangeNotifier {
private Object listeners; // space efficient listener hackery
/**
* Change this instance's value.
*
*
* The implementation in {@link ReadOnlyProperty} always throws {@link com.vaadin.data.Property.ReadOnlyException}.
*/
@Override
public void setValue(V value) {
throw new Property.ReadOnlyException();
}
/**
* Determine if this instance is read-only.
*
*
* The implementation in {@link ReadOnlyProperty} always returns true.
*/
@Override
public boolean isReadOnly() {
return true;
}
/**
* Change this instance's read-only setting.
*
*
* The implementation in {@link ReadOnlyProperty} throws {@link UnsupportedOperationException}
* if {@code readOnly} is false.
*/
@Override
public void setReadOnly(boolean readOnly) {
if (!readOnly)
throw new UnsupportedOperationException();
}
/**
* Issue a {@link com.vaadin.data.Property.ValueChangeEvent} to all registered
* {@link com.vaadin.data.Property.ValueChangeListener}s.
*/
protected void fireValueChange() {
if (this.listeners == null)
return;
final Property.ValueChangeEvent event = new ValueChangeEvent();
if (this.listeners instanceof Property.ValueChangeListener)
((Property.ValueChangeListener)this.listeners).valueChange(event);
else {
for (Property.ValueChangeListener listener : (Property.ValueChangeListener[])this.listeners)
listener.valueChange(event);
}
}
/**
* Invoked when the first {@link com.vaadin.data.Property.ValueChangeListener} has been added.
*
*
* The implementation in {@link ReadOnlyProperty} does nothing.
*/
protected void firstListenerAdded() {
}
/**
* Invoked when the last {@link com.vaadin.data.Property.ValueChangeListener} has been removed.
*
*
* The implementation in {@link ReadOnlyProperty} does nothing.
*/
protected void lastListenerRemoved() {
}
// Property.ValueChangeNotifier
@Override
public void addValueChangeListener(Property.ValueChangeListener listener) {
if (listener == null)
throw new IllegalArgumentException("null listener");
if (this.listeners == null) {
this.listeners = listener;
this.firstListenerAdded();
} else if (this.listeners instanceof Property.ValueChangeListener)
this.listeners = new Property.ValueChangeListener[] { (Property.ValueChangeListener)this.listeners, listener };
else {
final Property.ValueChangeListener[] oldArray = (Property.ValueChangeListener[])this.listeners;
final Property.ValueChangeListener[] newArray = new Property.ValueChangeListener[oldArray.length + 1];
System.arraycopy(oldArray, 0, newArray, 0, oldArray.length);
newArray[oldArray.length] = listener;
this.listeners = newArray;
}
}
@Override
public void removeValueChangeListener(Property.ValueChangeListener listener) {
if (listener == null || this.listeners == null)
return;
if (this.listeners instanceof Property.ValueChangeListener) {
if (!this.listeners.equals(listener))
return;
this.listeners = null;
this.lastListenerRemoved();
return;
}
final Property.ValueChangeListener[] oldArray = (Property.ValueChangeListener[])this.listeners;
int index = -1;
for (int i = 0; i < oldArray.length; i++) {
if (oldArray[i].equals(listener)) {
index = i;
break;
}
}
if (index == -1)
return;
switch (oldArray.length) {
case 0:
case 1:
throw new RuntimeException("internal error");
case 2:
this.listeners = oldArray[1 - index];
break;
default:
final Property.ValueChangeListener[] newArray = new Property.ValueChangeListener[oldArray.length - 1];
System.arraycopy(oldArray, 0, newArray, 0, index);
System.arraycopy(oldArray, index + 1, newArray, index, oldArray.length - index - 1);
this.listeners = newArray;
break;
}
}
@Override
@SuppressWarnings("deprecated")
public void addListener(Property.ValueChangeListener listener) {
this.addValueChangeListener(listener);
}
@Override
@SuppressWarnings("deprecated")
public void removeListener(Property.ValueChangeListener listener) {
this.removeValueChangeListener(listener);
}
// Property.ReadOnlyStatusChangeNotifier
@Override
public void addReadOnlyStatusChangeListener(Property.ReadOnlyStatusChangeListener listener) {
// nothing to do - read-only status never changes
}
@Override
public void removeReadOnlyStatusChangeListener(Property.ReadOnlyStatusChangeListener listener) {
// nothing to do - read-only status never changes
}
@Override
@SuppressWarnings("deprecated")
public void addListener(Property.ReadOnlyStatusChangeListener listener) {
this.addReadOnlyStatusChangeListener(listener);
}
@Override
@SuppressWarnings("deprecated")
public void removeListener(Property.ReadOnlyStatusChangeListener listener) {
this.removeReadOnlyStatusChangeListener(listener);
}
// ValueChangeEvent
private class ValueChangeEvent extends EventObject implements Property.ValueChangeEvent {
ValueChangeEvent() {
super(ReadOnlyProperty.this);
}
@Override
@SuppressWarnings("rawtypes")
public Property/**/ getProperty() {
return (Property)this.getSource();
}
}
}