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Types that extend and augment the Java Collections Framework.
/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999-2004 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. 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.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowledgement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgement may appear in the software itself,
* if and wherever such third-party acknowledgements normally appear.
*
* 4. The names "The Jakarta Project", "Commons", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact [email protected].
*
* 5. Products derived from this software may not be called "Apache"
* nor may "Apache" appear in their names without prior written
* permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
* ITS 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.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* FilterIterator that will not function
* until {@link #setIterator(Iterator) setIterator} is invoked.
*/
public FilterIterator() {
super();
}
/**
* Constructs a new FilterIterator that will not function
* until {@link #setPredicate(Predicate) setPredicate} is invoked.
*
* @param iterator the iterator to use
*/
public FilterIterator(Iterator iterator) {
super();
this.iterator = iterator;
}
/**
* Constructs a new FilterIterator that will use the
* given iterator and predicate.
*
* @param iterator the iterator to use
* @param predicate the predicate to use
*/
public FilterIterator(Iterator iterator, Predicate predicate) {
super();
this.iterator = iterator;
this.predicate = predicate;
}
//-----------------------------------------------------------------------
/**
* Returns true if the underlying iterator contains an object that
* matches the predicate.
*
* @return true if there is another object that matches the predicate
*/
public boolean hasNext() {
if (nextObjectSet) {
return true;
} else {
return setNextObject();
}
}
/**
* Returns the next object that matches the predicate.
*
* @return the next object which matches the given predicate
* @throws NoSuchElementException if there are no more elements that
* match the predicate
*/
public Object next() {
if (!nextObjectSet) {
if (!setNextObject()) {
throw new NoSuchElementException();
}
}
nextObjectSet = false;
return nextObject;
}
/**
* Removes from the underlying collection of the base iterator the last
* element returned by this iterator.
* This method can only be called
* if next() was called, but not after
* hasNext(), because the hasNext() call
* changes the base iterator.
*
* @throws IllegalStateException if hasNext() has already
* been called.
*/
public void remove() {
if (nextObjectSet) {
throw new IllegalStateException("remove() cannot be called");
}
iterator.remove();
}
//-----------------------------------------------------------------------
/**
* Gets the iterator this iterator is using.
*
* @return the iterator.
*/
public Iterator getIterator() {
return iterator;
}
/**
* Sets the iterator for this iterator to use.
* If iteration has started, this effectively resets the iterator.
*
* @param iterator the iterator to use
*/
public void setIterator(Iterator iterator) {
this.iterator = iterator;
}
//-----------------------------------------------------------------------
/**
* Gets the predicate this iterator is using.
*
* @return the predicate.
*/
public Predicate getPredicate() {
return predicate;
}
/**
* Sets the predicate this the iterator to use.
*
* @param predicate the transformer to use
*/
public void setPredicate(Predicate predicate) {
this.predicate = predicate;
}
//-----------------------------------------------------------------------
/**
* Set nextObject to the next object. If there are no more
* objects then return false. Otherwise, return true.
*/
private boolean setNextObject() {
while (iterator.hasNext()) {
Object object = iterator.next();
if (predicate.evaluate(object)) {
nextObject = object;
nextObjectSet = true;
return true;
}
}
return false;
}
}