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From Christopher Elkins <chr...@scardini.com>
Subject [collections] PATCH: unmodifiableIterator method to CollectionUtils
Date Mon, 25 Feb 2002 07:31:41 GMT
Hi, all.

The patch attached below adds an unmodifiableIterator method to
CollectionUtils. This is meant to parallel the unmodifiable* methods in
Java 2's util.Collections class.

-- 
Christopher Elkins


Index: src/java/org/apache/commons/collections/CollectionUtils.java
===================================================================
RCS file: /home/cvspublic/jakarta-commons/collections/src/java/org/apache/commons/collections/CollectionUtils.java,v
retrieving revision 1.7
diff -u -r1.7 CollectionUtils.java
--- src/java/org/apache/commons/collections/CollectionUtils.java	10 Feb 2002 08:07:42 -0000
1.7
+++ src/java/org/apache/commons/collections/CollectionUtils.java	25 Feb 2002 07:28:03 -0000
@@ -106,6 +106,39 @@
     }
 
     /**
+     * Returns an unmodifiable view of the specified iterator. Attempts to
+     * modify the returned iterator result in an UnsupportedOperationException.
+     *
+     * @param iterator the iterator for which an unmodifiable view is to be
+     *        returned
+     * @return an unmodifiable view of the specified iterator
+     */
+    public static Iterator unmodifiableIterator(Iterator iterator) {
+        return (iterator != null) ? new ImmutableIterator(iterator) :
+            CollectionUtils.EMPTY_ITERATOR;
+    }
+
+    private static class ImmutableIterator implements Iterator {
+        private final Iterator iterator;
+
+        public ImmutableIterator(Iterator iterator) {
+            this.iterator = iterator;
+        }
+
+        public boolean hasNext() {
+            return iterator.hasNext();
+        }
+
+        public Object next() {
+            return iterator.next();
+        }
+
+        public void remove() {
+            throw new UnsupportedOperationException();
+        }
+    }
+
+    /**
      * Returns a {@link Collection} containing the union
      * of the given {@link Collection}s.
      * <p>
Index: src/test/org/apache/commons/collections/TestCollectionUtils.java
===================================================================
RCS file: /home/cvspublic/jakarta-commons/collections/src/test/org/apache/commons/collections/TestCollectionUtils.java,v
retrieving revision 1.2
diff -u -r1.2 TestCollectionUtils.java
--- src/test/org/apache/commons/collections/TestCollectionUtils.java	14 Jul 2001 23:33:27
-0000	1.2
+++ src/test/org/apache/commons/collections/TestCollectionUtils.java	25 Feb 2002 07:28:03
-0000
@@ -310,4 +310,12 @@
         assertTrue(CollectionUtils.isEqualCollection(a,b));
         assertTrue(CollectionUtils.isEqualCollection(b,a));
     }
+
+    public void testUnmodifiableIterator() {
+        Iterator iterator = CollectionUtils.unmodifiableIterator(CollectionUtils.EMPTY_ITERATOR);
+        try {
+            iterator.remove();
+            fail("Should raise an UnsupportedOperationException");
+        } catch (UnsupportedOperationException e) {}
+    }
 }

--
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