[COLLECTIONS-780] Add

org.apache.commons.collections4.EnumerationUtils.asIterable(Enumeration).

src/changes/changes.xml

@@ -108,6 +108,9 @@
     <action dev="ggregory" type="fix" due-to="Dominik Stadler">
       Fix links to release notes and update contents for 4.4 #127.
     </action>
+    <action issue="COLLECTIONS-780" dev="ggregory" type="add" due-to="Gary Gregory">
+      Add org.apache.commons.collections4.EnumerationUtils.asIterable(Enumeration).
+    </action>
   </release>
   <release version="4.4" date="2019-07-05" description="Maintenance release.">
     <action issue="COLLECTIONS-710" dev="ggregory" type="fix" due-to="Yu Shi, Gary Gregory">

src/main/java/org/apache/commons/collections4/EnumerationUtils.java

@@ -22,6 +22,7 @@ import java.util.List;
 import java.util.StringTokenizer;
 
 import org.apache.commons.collections4.iterators.EnumerationIterator;
+import org.apache.commons.collections4.iterators.IteratorIterable;
 
 /**
  * Provides utility methods for {@link Enumeration} instances.
@@ -33,7 +34,22 @@ public class EnumerationUtils {
     /**
      * EnumerationUtils is not normally instantiated.
      */
-    private EnumerationUtils() {}
+    private EnumerationUtils() {
+        // no instances.
+    }
+
+    /**
+     * Creates an {@link Iterable} that wraps an {@link Enumeration}. The returned {@link Iterable} can be used for a
+     * single iteration.
+     *
+     * @param <T> the element type
+     * @param enumeration the enumeration to use, may not be null
+     * @return a new, single use {@link Iterable}
+     * @since 4.5
+     */
+    public static <T> Iterable<T> asIterable(final Enumeration<T> enumeration) {
+        return new IteratorIterable<>(new EnumerationIterator<>(enumeration));
+    }
 
     /**
      * Returns the {@code index}-th value in the {@link Enumeration}, throwing
@@ -51,8 +67,8 @@ public class EnumerationUtils {
      * @since 4.1
      */
     public static <T> T get(final Enumeration<T> e, final int index) {
+        CollectionUtils.checkIndexBounds(index);
         int i = index;
-        CollectionUtils.checkIndexBounds(i);
         while (e.hasMoreElements()) {
             i--;
             if (i == -1) {
@@ -92,4 +108,5 @@ public class EnumerationUtils {
         }
         return result;
     }
+
 }

src/test/java/org/apache/commons/collections4/EnumerationUtilsTest.java

@@ -18,11 +18,13 @@ package org.apache.commons.collections4;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.fail;
 
 import java.util.ArrayList;
 import java.util.Enumeration;
 import java.util.Hashtable;
+import java.util.Iterator;
 import java.util.List;
 import java.util.StringTokenizer;
 import java.util.Vector;
@@ -58,6 +60,30 @@ public class EnumerationUtilsTest {
         assertTrue(!en.hasMoreElements());
     }
 
+    @Test
+    public void testAsIterableFor() {
+        final Vector<String> vector = new Vector<>();
+        vector.addElement("zero");
+        vector.addElement("one");
+        Enumeration<String> en = vector.elements();
+        final Iterator<String> iterator = EnumerationUtils.asIterable(en).iterator();
+        assertTrue(iterator.hasNext());
+        assertEquals("zero", iterator.next());
+        assertTrue(iterator.hasNext());
+        assertEquals("one", iterator.next());
+        assertFalse(iterator.hasNext());
+    }
+
+    @Test
+    public void testAsIterableForNull() {
+        try {
+            EnumerationUtils.asIterable((Enumeration) null).iterator().next();
+            fail("Expecting NullPointerException");
+        } catch (final NullPointerException ex) {
+            // success
+        }
+    }
+
     @Test
     public void testToListWithHashtable() {
         final Hashtable<String, Integer> expected = new Hashtable<>();