/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2004-2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
package org.geotools.resources;
import java.io.Serializable;
import java.util.AbstractList;
import org.geotools.util.CheckedCollection;
/**
* An unmodifiable view of an array. Invoking
*
* <blockquote><code>
* UnmodifiableArrayList.wrap(array);
* </code></blockquote>
*
* is equivalent to
*
* <blockquote><code>
* {@linkplain Collections#unmodifiableList Collections.unmodifiableList}({@linkplain
* Arrays#asList Arrays.asList}(array)));
* </code></blockquote>
*
* But this class provides a very slight performance improvement since it uses one less level
* of indirection.
*
* @param <E> The type of elements in the list.
*
* @since 2.1
* @source $URL$
* @version $Id$
* @author Martin Desruisseaux (IRD)
*/
public class UnmodifiableArrayList<E> extends AbstractList<E>
implements CheckedCollection<E>, Serializable
{
/**
* For compatibility with different versions.
*/
private static final long serialVersionUID = -3605810209653785967L;
/**
* The wrapped array.
*/
private final E[] array;
/**
* Creates a new instance of an array list. A direct reference to the given array is retained
* (i.e. the array is <strong>not</strong> cloned). Consequently the given array should not
* be modified after construction if this list is intented to be immutable.
* <p>
* This constructor is for subclassing only. Users should invoke the {@link #wrap} static
* factory method, which provides more convenient handling of parameterized types.
*
* @param array The array to wrap.
*/
protected UnmodifiableArrayList(final E[] array) {
this.array = array;
}
/**
* Creates a new instance of an array list. A direct reference to the given array is retained
* (i.e. the array is <strong>not</strong> cloned). Consequently the given array should not
* be modified after construction if this list is intented to be immutable.
*
* @param <E> The type of elements in the list.
* @param array The array to wrap.
* @return The given array wrapped in an unmodifiable list.
*
* @since 2.5
*/
public static <E> UnmodifiableArrayList<E> wrap(final E[] array) {
return new UnmodifiableArrayList<E>(array);
}
/**
* Returns the element type of the wrapped array.
*
* @return The type of elements in the list.
*/
@SuppressWarnings("unchecked") // Safe if this instance was created safely with wrap(E[]).
public Class<E> getElementType() {
return (Class) array.getClass().getComponentType();
}
/**
* Returns the list size.
*/
public int size() {
return array.length;
}
/**
* Returns the element at the specified index.
*/
public E get(final int index) {
return array[index];
}
/**
* Returns the index in this list of the first occurence of the specified
* element, or -1 if the list does not contain this element. This method
* is overridden only for performance reason (the default implementation
* would work as well).
*
* @param object The element to search for.
*/
@Override
public int indexOf(final Object object) {
if (object == null) {
for (int i=0; i<array.length; i++) {
if (array[i] == null) {
return i;
}
}
} else {
for (int i=0; i<array.length; i++) {
if (object.equals(array[i])) {
return i;
}
}
}
return -1;
}
/**
* Returns the index in this list of the last occurence of the specified
* element, or -1 if the list does not contain this element. This method
* is overridden only for performance reason (the default implementation
* would work as well).
*
* @param object The element to searcch for.
*/
@Override
public int lastIndexOf(final Object object) {
int i = array.length;
if (object == null) {
while (--i >= 0) {
if (array[i] == null) {
break;
}
}
} else {
while (--i >= 0) {
if (object.equals(array[i])) {
break;
}
}
}
return i;
}
/**
* Returns {@code true} if this collection contains the specified element.
* This method is overridden only for performance reason (the default implementation
* would work as well).
*
* @param object The element to check for existence.
*/
@Override
public boolean contains(final Object object) {
int i = array.length;
if (object == null) {
while (--i >= 0) {
if (array[i] == null) {
return true;
}
}
} else {
while (--i >= 0) {
if (object.equals(array[i])) {
return true;
}
}
}
return false;
}
}