I forgot to send the test case in the first mail, so here it comes.
--
Jan Sorensen
aragost
----- Original Message -----
From: "Jan Sorensen" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, September 03, 2001 10:10 AM
Subject: [PATCH][collections] FilterIterator
> org.apache.commons.collections.FilterIterator implements the Iterator
> interface. But the Iterator is advanced with the hasNext() method, and not
> with the next(). That means that it relies on being used with alternate
> calls to hasNext() and next(), like:
> while (iter.hasNext()) { .... iter.next(); ... }
>
> Multiple calls to next() would return the same element, and calls to
> hasNext() skip over elements.
>
> This patch fix this, and also makes the remove() throw an
> UnsupportedOperationException. The underlying iterator might not be in
sync
> with the FilterIterator so remove() is a bit hard to implement.
>
> --
> Jan Sorensen
> aragost
>
> Index: FilterIterator.java
> ===================================================================
> RCS file:
>
/home/cvspublic/jakarta-commons/collections/src/java/org/apache/commons/coll
> ections/FilterIterator.java,v
> retrieving revision 1.1
> diff -u -r1.1 FilterIterator.java
> --- FilterIterator.java 2001/05/06 11:04:25 1.1
> +++ FilterIterator.java 2001/09/03 07:48:13
> @@ -7,8 +7,8 @@
> */
> package org.apache.commons.collections;
>
> -import java.util.Enumeration;
> 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.
> @@ -20,7 +20,9 @@
>
> /** Holds value of property predicate. */
> private Predicate predicate;
> +
> private Object nextObject;
> + private boolean nextObjectSet = false;
>
>
>
>
//-------------------------------------------------------------------------
> @@ -39,20 +41,44 @@
> // 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;
> + }
> +
> + public void remove() {
> + /* The unlying iterator might not be in sync, so we can't forward
> + * the call.
> + */
> + throw new UnsupportedOperationException();
> + }
> +
> + // Private methods
> +
>
//-------------------------------------------------------------------------
> + /** Set nextObject to the next object. If there is no more objects,
> 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;
> - }
> -
> - public Object next() {
> - return nextObject;
> }
>
> // Properties
>
>
TestFilterIterator.java
