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An alternative HBase client library for applications requiring fully
asynchronous, non-blocking and thread-safe HBase connectivity.
/*
* Copyright (C) 2010-2012 The Async HBase Authors. All rights reserved.
* This file is part of Async HBase.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name of the StumbleUpon nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
package org.hbase.async;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.NoSuchElementException;
/**
* An immutable {@link List} that holds only a single non-{@code null} value.
* @param The type of the singleton element.
*/
final class SingletonList implements List {
private final E element;
/**
* Constructor.
* @param element The only element that will ever be in this list.
* Must not be {@code null}.
*/
public SingletonList(final E element) {
if (element == null) {
throw new NullPointerException("element");
}
this.element = element;
}
public String toString() {
return "[" + element + ']';
}
@Override
public int size() {
return 1;
}
@Override
public boolean isEmpty() {
return false;
}
@Override
public boolean contains(final Object o) {
return element.equals(o);
}
@Override
public Iterator iterator() {
return new Iter(element);
}
@Override
public Object[] toArray() {
final Object[] array = new Object[1];
array[0] = element;
return array;
}
@Override
@SuppressWarnings("unchecked")
public T[] toArray(final T[] a) {
if (a.length < 1) {
return (T[]) toArray();
}
a[0] = (T) element;
if (a.length > 1) {
a[1] = null;
}
return a;
}
@Override
public boolean add(final E e) {
throw new UnsupportedOperationException();
}
@Override
public boolean remove(final Object o) {
throw new UnsupportedOperationException();
}
@Override
public boolean containsAll(final Collection c) {
if (c.size() != 1) {
return false;
}
return c.contains(element);
}
@Override
public boolean addAll(final Collection c) {
throw new UnsupportedOperationException();
}
@Override
public boolean addAll(final int index, final Collection c) {
throw new UnsupportedOperationException();
}
@Override
public boolean removeAll(final Collection c) {
throw new UnsupportedOperationException();
}
@Override
public boolean retainAll(final Collection c) {
throw new UnsupportedOperationException();
}
@Override
public void clear() {
throw new UnsupportedOperationException();
}
@Override
public boolean equals(final Object other) {
if (other == null || !(other instanceof SingletonList)) {
return false;
}
return element.equals(((SingletonList) other).element);
}
@Override
public int hashCode() {
return 31 + element.hashCode();
}
@Override
public E get(final int index) {
if (index != 0) {
throw new IndexOutOfBoundsException("only 1 element but index=" + index);
}
return element;
}
@Override
public E set(final int index, final E element) {
throw new UnsupportedOperationException();
}
@Override
public void add(final int index, final E element) {
throw new UnsupportedOperationException();
}
@Override
public E remove(final int index) {
throw new UnsupportedOperationException();
}
@Override
public int indexOf(final Object o) {
return o.equals(element) ? 0 : -1;
}
@Override
public int lastIndexOf(Object o) {
return o.equals(element) ? 0 : -1;
}
@Override
public ListIterator listIterator() {
return new Iter(element);
}
@Override
public ListIterator listIterator(final int index) {
if (index != 0) {
throw new IndexOutOfBoundsException("only 1 element but index=" + index);
}
return new Iter(element);
}
@Override
public List subList(final int fromIndex, final int toIndex) {
if (fromIndex == 0 && toIndex == 1) {
return this;
}
throw new IndexOutOfBoundsException("only 1 element but requested ["
+ fromIndex + "; " + toIndex + ']');
}
private static final class Iter implements ListIterator {
private final E element;
private boolean returned = false;
public Iter(final E element) {
this.element = element;
}
@Override
public boolean hasNext() {
return !returned;
}
@Override
public E next() {
if (returned) {
throw new NoSuchElementException();
}
returned = true;
return element;
}
@Override
public boolean hasPrevious() {
return returned;
}
@Override
public E previous() {
if (!returned) {
throw new NoSuchElementException();
}
returned = false;
return element;
}
@Override
public int nextIndex() {
return returned ? 0 : 1;
}
@Override
public int previousIndex() {
return returned ? -1 : 0;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
@Override
public void set(final E e) {
throw new UnsupportedOperationException();
}
@Override
public void add(final E e) {
throw new UnsupportedOperationException();
}
}
}