org.glassfish.pfl.basic.contain.DenseIntMapImpl Maven / Gradle / Ivy
/*
* Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0, which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.glassfish.pfl.basic.contain ;
import java.util.ArrayList ;
/** Utility for managing mappings from densely allocated integer
* keys to arbitrary objects. This should only be used for
* keys in the range 0..max such that "most" of the key space is actually
* used.
*/
public class DenseIntMapImpl implements IntMap
{
private ArrayList list = new ArrayList() ;
private void checkKey( int key )
{
if (key < 0)
throw new IllegalArgumentException( "Key must be >= 0." ) ;
}
/** If key >= 0, return the value bound to key, or null if none.
* Throws IllegalArgumentException if key <0.
*/
public E get( int key )
{
checkKey( key ) ;
E result = null ;
if (key < list.size())
result = list.get( key ) ;
return result ;
}
/** If key >= 0, bind value to the key.
* Throws IllegalArgumentException if key <0.
*/
public void set( int key, E value )
{
checkKey( key ) ;
extend( key ) ;
list.set( key, value ) ;
}
private void extend( int index )
{
if (index >= list.size()) {
list.ensureCapacity( index + 1 ) ;
int max = list.size() ;
while (max++ <= index)
list.add( null ) ;
}
}
}