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Patch that stops next() continually returning null if hasNext is not

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called in the standard way. ie)

(cf: "Juozas Baliuka" <baliuka@mwm.lt>)

while(true) {
    filterIterator.next();
}

This should eventually throw NoSuchElementException, but it returns null
forever.

Submitted by:  Jan Sorensen <jan.sorensen@aragost.com>


git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/collections/trunk@130505 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Henri Yandell 2001-10-19 20:18:21 +00:00
parent d2d3f62e25
commit 21500f60e7
1 changed files with 103 additions and 72 deletions
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175
src/java/org/apache/commons/collections/FilterIterator.java
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@ -1,72 +1,103 @@
/*
* Copyright (C) The Apache Software Foundation. All rights reserved.
*
* This software is published under the terms of the Apache Software License
* version 1.1, a copy of which has been included with this distribution in
* the LICENSE file.
*/
package org.apache.commons.collections;
import java.util.Enumeration;
import java.util.Iterator;
/** A Proxy {@link Iterator Iterator} which takes a {@link Predicate Predicate} instance to filter
* out objects from an underlying {@link Iterator Iterator} instance.
*
* @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
*/
public class FilterIterator extends ProxyIterator {
/** Holds value of property predicate. */
private Predicate predicate;
private Object nextObject;
//-------------------------------------------------------------------------
public FilterIterator() {
}
public FilterIterator( Iterator iterator ) {
super( iterator );
}
public FilterIterator( Iterator iterator, Predicate predicate ) {
super( iterator );
this.predicate = predicate;
}
// Iterator interface
//-------------------------------------------------------------------------
public boolean hasNext() {
Iterator iterator = getIterator();
Predicate predicate = getPredicate();
while ( iterator.hasNext() ) {
Object object = iterator.next();
if ( predicate.evaluate( object ) ) {
nextObject = object;
return true;
}
}
return false;
}
public Object next() {
return nextObject;
}
// Properties
//-------------------------------------------------------------------------
/** Getter for property predicate.
* @return Value of property predicate.
*/
public Predicate getPredicate() {
return predicate;
}
/** Setter for property predicate.
* @param predicate New value of property predicate.
*/
public void setPredicate(Predicate predicate) {
this.predicate = predicate;
}
}
/*
* Copyright (C) The Apache Software Foundation. All rights reserved.
*
* This software is published under the terms of the Apache Software License
* version 1.1, a copy of which has been included with this distribution in
* the LICENSE file.
*/
package org.apache.commons.collections;
import java.util.Iterator;
import java.util.NoSuchElementException;
/** A Proxy {@link Iterator Iterator} which takes a {@link Predicate Predicate} instance to filter
* out objects from an underlying {@link Iterator Iterator} instance.
*
* @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
* @author Jan Sorensen
*/
public class FilterIterator extends ProxyIterator {
/** Holds value of property predicate. */
private Predicate predicate;
private Object nextObject;
private boolean nextObjectSet = false;
//-------------------------------------------------------------------------
public FilterIterator() {
}
public FilterIterator( Iterator iterator ) {
super( iterator );
}
public FilterIterator( Iterator iterator, Predicate predicate ) {
super( iterator );
this.predicate = predicate;
}
// Iterator interface
//-------------------------------------------------------------------------
public boolean hasNext() {
if ( nextObjectSet ) {
return true;
} else {
return setNextObject();
}
}
public Object next() {
if ( !nextObjectSet ) {
if (!setNextObject()) {
throw new NoSuchElementException();
}
}
nextObjectSet = false;
return nextObject;
}
/**
* Always throws UnsupportedOperationException as this class
* does look-ahead with its internal iterator.
*/
public void remove() {
throw new UnsupportedOperationException();
}
// Properties
//-------------------------------------------------------------------------
/** Getter for property predicate.
* @return Value of property predicate.
*/
public Predicate getPredicate() {
return predicate;
}
/** Setter for property predicate.
* @param predicate New value of property predicate.
*/
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() {
Iterator iterator = getIterator();
Predicate predicate = getPredicate();
while ( iterator.hasNext() ) {
Object object = iterator.next();
if ( predicate.evaluate( object ) ) {
nextObject = object;
nextObjectSet = true;
return true;
}
}
return false;
}
}