Add special cases for Set and Bag to CollectionUtils cardinality()

bug 28629, from Jon Schewe


git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/collections/trunk@131678 13f79535-47bb-0310-9956-ffa450edef68

RELEASE-NOTES.html

@@ -43,6 +43,7 @@ No interface changes, or deprecations have occurred.
 <li>Functors - Add get methods to retrieve internal state [27515]</li>
 <li>Functors - Add additional getInstance() methods for consistency [27856,27857]</li>
 <li>CollectionUtils - get(Object,int) method now supports primitive arrays</li>
+<li>CollectionUtils - cardinality() now works faster for Set and Bag instances [28629]</li>
 <li>CollectionUtils - Add size(Object) method to find the size of various collection-like objects [27909]</li>
 <li>SingletonIterator - make remove() functionality optional</li>
 <li>AbstractLinkedList/NodeCachingLinkedList - added getValue() and setValue() to Node, and made everything use them</li>

project.xml

@@ -254,6 +254,9 @@
     <contributor>
       <name>Joe Raysa</name>
     </contributor>
+    <contributor>
+      <name>Jon Schewe</name>
+    </contributor>
     <contributor>
       <name>Michael Smith</name>
     </contributor>

src/java/org/apache/commons/collections/CollectionUtils.java

@@ -38,7 +38,7 @@ import org.apache.commons.collections.collection.UnmodifiableCollection;
  * Provides utility methods and decorators for {@link Collection} instances.
  *
  * @since Commons Collections 1.0
- * @version $Revision: 1.60 $ $Date: 2004/04/01 22:43:13 $
+ * @version $Revision: 1.61 $ $Date: 2004/04/27 20:00:18 $
  * 
  * @author Rodney Waldhoff
  * @author Paul Jack
@@ -50,6 +50,7 @@ import org.apache.commons.collections.collection.UnmodifiableCollection;
  * @author Janek Bogucki
  * @author Phil Steitz
  * @author Steven Melzer
+ * @author Jon Schewe
  */
 public class CollectionUtils {
 
@@ -319,24 +320,29 @@ public class CollectionUtils {
     }
 
     /**
-     * Returns the number of occurrences of <i>obj</i>
+     * Returns the number of occurrences of <i>obj</i> in <i>coll</i>.
-     * in <i>col</i>.
      *
      * @param obj  the object to find the cardinality of
-     * @param col  the collection to search
+     * @param coll  the collection to search
-     * @return the the number of occurrences of obj in col
+     * @return the the number of occurrences of obj in coll
      */
-    public static int cardinality(Object obj, final Collection col) {
+    public static int cardinality(Object obj, final Collection coll) {
+        if (coll instanceof Set) {
+            return (coll.contains(obj) ? 1 : 0);
+        }
+        if (coll instanceof Bag) {
+            return ((Bag) coll).getCount(obj);
+        }
         int count = 0;
-        if(null == obj) {
+        if (obj == null) {
-            for(Iterator it = col.iterator();it.hasNext();) {
+            for (Iterator it = coll.iterator();it.hasNext();) {
-                if(null == it.next()) {
+                if (it.next() == null) {
                     count++;
                 }
             }
         } else {
-            for(Iterator it = col.iterator();it.hasNext();) {
+            for (Iterator it = coll.iterator();it.hasNext();) {
-                if(obj.equals(it.next())) {
+                if (obj.equals(it.next())) {
                     count++;
                 }
             }

src/test/org/apache/commons/collections/TestCollectionUtils.java

@@ -50,7 +50,7 @@ import org.apache.commons.collections.collection.UnmodifiableCollection;
  * @author Phil Steitz
  * @author Steven Melzer
  * 
- * @version $Revision: 1.37 $ $Date: 2004/04/01 22:43:12 $
+ * @version $Revision: 1.38 $ $Date: 2004/04/27 20:00:18 $
  */
 public class TestCollectionUtils extends TestCase {
     
@@ -113,17 +113,39 @@ public class TestCollectionUtils extends TestCase {
     }
 
     public void testCardinality() {
-        assertEquals(1,CollectionUtils.cardinality("a",collectionA));
+        assertEquals(1, CollectionUtils.cardinality("a", collectionA));
-        assertEquals(2,CollectionUtils.cardinality("b",collectionA));
+        assertEquals(2, CollectionUtils.cardinality("b", collectionA));
-        assertEquals(3,CollectionUtils.cardinality("c",collectionA));
+        assertEquals(3, CollectionUtils.cardinality("c", collectionA));
-        assertEquals(4,CollectionUtils.cardinality("d",collectionA));
+        assertEquals(4, CollectionUtils.cardinality("d", collectionA));
-        assertEquals(0,CollectionUtils.cardinality("e",collectionA));
+        assertEquals(0, CollectionUtils.cardinality("e", collectionA));
 
-        assertEquals(0,CollectionUtils.cardinality("a",collectionB));
+        assertEquals(0, CollectionUtils.cardinality("a", collectionB));
-        assertEquals(4,CollectionUtils.cardinality("b",collectionB));
+        assertEquals(4, CollectionUtils.cardinality("b", collectionB));
-        assertEquals(3,CollectionUtils.cardinality("c",collectionB));
+        assertEquals(3, CollectionUtils.cardinality("c", collectionB));
-        assertEquals(2,CollectionUtils.cardinality("d",collectionB));
+        assertEquals(2, CollectionUtils.cardinality("d", collectionB));
-        assertEquals(1,CollectionUtils.cardinality("e",collectionB));
+        assertEquals(1, CollectionUtils.cardinality("e", collectionB));
+
+        Set set = new HashSet();
+        set.add("A");
+        set.add("C");
+        set.add("E");
+        set.add("E");
+        assertEquals(1, CollectionUtils.cardinality("A", set));
+        assertEquals(0, CollectionUtils.cardinality("B", set));
+        assertEquals(1, CollectionUtils.cardinality("C", set));
+        assertEquals(0, CollectionUtils.cardinality("D", set));
+        assertEquals(1, CollectionUtils.cardinality("E", set));
+
+        Bag bag = new HashBag();
+        bag.add("A", 3);
+        bag.add("C");
+        bag.add("E");
+        bag.add("E");
+        assertEquals(3, CollectionUtils.cardinality("A", bag));
+        assertEquals(0, CollectionUtils.cardinality("B", bag));
+        assertEquals(1, CollectionUtils.cardinality("C", bag));
+        assertEquals(0, CollectionUtils.cardinality("D", bag));
+        assertEquals(2, CollectionUtils.cardinality("E", bag));
     }
     
     public void testCardinalityOfNull() {