Mega Code Archive
Enumeration interface which enumerates the items of an array
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/**
* The utillib library.
* More information is available at http://www.jinchess.com/.
* Copyright (C) 2002 Alexander Maryanovsky.
* All rights reserved.
*
* The utillib 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; either version 2 of the
* License, or (at your option) any later version.
*
* The utillib 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.
*
* You should have received a copy of the GNU Lesser General Public License
* along with utillib library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
import java.util.Enumeration;
import java.util.NoSuchElementException;
/**
* An implementation of the Enumeration interface which enumerates the items of
* an array. Note: This class is not thread safe.
*/
public class ArrayEnumeration implements Enumeration{
/**
* The array.
*/
private Object [] arr;
/**
* The index of the first enumerated item.
*/
private final int offset;
/**
* The amount of the enumerated items.
*/
private final int count;
/**
* The index of the next returned item.
*/
private int curIndex;
/**
* Creates a new ArrayEnumeration which enumerates the items of the given
* array. The first <code>count</code> items starting at index
* <code>offset</code> are enumerated.
*
* @throws IllegalArgumentException if the offset and/or count parameters are
* invalid.
*/
public ArrayEnumeration(Object [] arr, int offset, int count){
if ((offset < 0) || (offset + count > arr.length) || (count < 0))
throw new IllegalArgumentException("Invalid enumeration range");
this.arr = new Object[arr.length];
System.arraycopy(arr, 0, this.arr, 0, arr.length);
this.offset = offset;
this.count = count;
curIndex = offset;
}
/**
* Creates a new ArrayEnumeration which enumerates all the items of the given
* array.
*/
public ArrayEnumeration(Object [] arr){
this(arr, 0, arr.length);
}
/**
* Returns the next element in the enumeration.
*/
public Object nextElement(){
if (!hasMoreElements())
throw new NoSuchElementException();
Object item = arr[curIndex];
arr[curIndex++] = null; // We don't want to keep a reference to it any longer than we have to.
if (!hasMoreElements())
arr = null; // Neither do we need this any more.
return item;
}
/**
* Returns true if there are more elements in the enumeration.
*/
public boolean hasMoreElements(){
return curIndex < offset + count;
}
}
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