Applying Dave Meikle's patch to COLLECTIONS-194 - adding a populateMap method to MapUtils

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/collections/trunk@657293 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -28,6 +28,7 @@ import java.util.Properties;
 import java.util.ResourceBundle;
 import java.util.SortedMap;
 import java.util.TreeMap;
+import java.util.Collection;
 
 import org.apache.commons.collections.map.FixedSizeMap;
 import org.apache.commons.collections.map.FixedSizeSortedMap;
@@ -1642,4 +1643,36 @@ public class MapUtils {
         return LazySortedMap.decorate(map, transformerFactory);
     }
 
+    /**
+     * <p>
+     * Populates a Map using the supplied <code>Transformer</code> to transform the collection
+     * values into keys, using the unaltered collection value as the value in the <code>Map</code>.
+     * </p>
+     * @param map the <code>Map</code> to populate.
+     * @param collection the <code>Collection</code> to use as input values for the map.
+     * @param keyTransformer the <code>Transformer</code> used to transform the collection value into a key value
+     * @throws NullPointerException if the map, collection or transformer are null
+     */
+    public static void populateMap(Map map, Collection collection, Transformer keyTransformer) {
+        populateMap(map, collection, keyTransformer, TransformerUtils.nopTransformer());
+    }
+
+    /**
+     * <p>
+     * Populates a Map using the supplied <code>Transformer</code>s to transform the collection
+     * values into keys and values.
+     * </p>
+     * @param map the <code>Map</code> to populate.
+     * @param collection the <code>Collection</code> to use as input values for the map.
+     * @param keyTransformer the <code>Transformer</code> used to transform the collection value into a key value
+     * @param valueTransformer the <code>Transformer</code> used to transform the collection value into a value
+     * @throws NullPointerException if the map, collection or transformers are null
+     */
+    public static void populateMap(Map map, Collection collection, Transformer keyTransformer, Transformer valueTransformer) {
+        Iterator iter = collection.iterator();
+        while (iter.hasNext()) {
+            Object temp = iter.next();
+            map.put(keyTransformer.transform(temp), valueTransformer.transform(temp));
+        }
+    }
 }

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

@@ -26,6 +26,8 @@ import java.util.Map;
 import java.util.ResourceBundle;
 import java.util.Set;
 import java.util.TreeMap;
+import java.util.List;
+import java.util.ArrayList;
 
 import junit.framework.Test;
 
@@ -34,6 +36,7 @@ import org.apache.commons.collections.keyvalue.DefaultMapEntry;
 import org.apache.commons.collections.map.LazyMap;
 import org.apache.commons.collections.map.PredicatedMap;
 import org.apache.commons.collections.map.TestPredicatedMap;
+import org.apache.commons.collections.collection.TestTransformedCollection;
 
 /**
  * Tests for MapUtils.
@@ -805,4 +808,39 @@ public class TestMapUtils extends BulkTest {
         assertEquals(false, MapUtils.isNotEmpty(map));
     }
 
+    public void testPopulateMap() {
+        // Setup Test Data
+        List list = new ArrayList();
+        list.add("1");
+        list.add("3");
+        list.add("5");
+        list.add("7");
+        list.add("2");
+        list.add("4");
+        list.add("6");
+
+        // Now test key transform population
+        Map map = new HashMap();
+        MapUtils.populateMap(map, list, TestTransformedCollection.STRING_TO_INTEGER_TRANSFORMER);
+        assertEquals(list.size(), map.size());
+
+        for (int i = 0; i < list.size(); i++) {
+            assertEquals(true, map.containsKey(new Integer((String) list.get(i))));
+            assertEquals(false, map.containsKey(list.get(i)));
+            assertEquals(true, map.containsValue(list.get(i)));
+            assertEquals(list.get(i), map.get(new Integer((String) list.get(i))));
+        }
+
+        // Now test both Key-Value transform population
+        map = new HashMap();
+        MapUtils.populateMap(map, list, TestTransformedCollection.STRING_TO_INTEGER_TRANSFORMER, TestTransformedCollection.STRING_TO_INTEGER_TRANSFORMER);
+
+        assertEquals(list.size(), map.size());
+        for (int i = 0; i < list.size(); i++) {
+            assertEquals(true, map.containsKey(new Integer((String) list.get(i))));
+            assertEquals(false, map.containsKey(list.get(i)));
+            assertEquals(true, map.containsValue(new Integer((String) list.get(i))));
+            assertEquals(new Integer((String) list.get(i)), map.get(new Integer((String) list.get(i))));
+        }
+    }
 }