functionaljava
diff --git a/Collapse file
‎core/src/main/java/fj/data/HashMap.java‎
Copy file name to clipboardExpand all lines: core/src/main/java/fj/data/HashMap.java
+12Lines changed: 12 additions & 0 deletions b/Collapse file
‎core/src/main/java/fj/data/HashMap.java‎
Copy file name to clipboardExpand all lines: core/src/main/java/fj/data/HashMap.java
+12Lines changed: 12 additions & 0 deletions
diff --git a/Collapse file
‎core/src/test/fj/data/CheckHashMap.scala‎
Copy file name to clipboardExpand all lines: core/src/test/fj/data/CheckHashMap.scala
+15-1Lines changed: 15 additions & 1 deletion b/Collapse file
‎core/src/test/fj/data/CheckHashMap.scala‎
Copy file name to clipboardExpand all lines: core/src/test/fj/data/CheckHashMap.scala
+15-1Lines changed: 15 additions & 1 deletion
@@ -243,6 +243,18 @@ public Option<V> getDelete(final K k) {
     return fromNull(m.remove(new Key<K>(k, e, h)));
   }
 
+  public <A, B> HashMap<A, B> map(F<K, A> keyFunction,
+                                              F<V, B> valueFunction,
+                                              Equal<A> equal, Hash<A> hash) {
+      final HashMap hashMap = new HashMap(equal, hash);
+      for (K key : keys()) {
+          final A newKey = keyFunction.f(key);
+          final B newValue = valueFunction.f(get(key).some());
+          hashMap.set(newKey, newValue);
+      }
+      return hashMap;
+  }
+
   public List<P2<K, V>> toList() {
     return keys().map(new F<K, P2<K, V>>() {
       public P2<K, V> f(final K k) {
 
@@ -4,7 +4,7 @@ package data
 import org.scalacheck.Prop._
 import ArbitraryHashMap._
 import Equal.{intEqual, stringEqual, optionEqual}
-import Hash.intHash
+import Hash.{intHash, stringHash}
 import fj.data.Option._
 import scala.collection.JavaConversions._
 import org.scalacheck.{Arbitrary, Properties}
@@ -69,4 +69,18 @@ object CheckHashMap extends Properties("HashMap") {
       .forall((e: (Int, Iterable[P2[Int, String]])) => e._2
       .exists((elem: P2[Int, String]) => optionEqual(stringEqual).eq(map.get(e._1), Option.some(elem._2))))
   })
+
+  property("map") = forAll((m: HashMap[Int, String]) => {
+    val keyFunction: F[Int, String] = (i: Int) => i.toString
+    val valueFunction: (String) => String = (s: String) => s + "a"
+    val mapped = m.map(keyFunction, valueFunction, stringEqual, stringHash)
+    val keysAreEqual = m.keys().map(keyFunction).toSet == mapped.keys.toSet
+    val appliedFunctionsToKeysAndValues: Boolean = m.keys().forall((key: Int) => {
+      val mappedValue = mapped.get(keyFunction.f(key))
+      val oldValueMapped = some(valueFunction.f(m.get(key).some()))
+      Equal.optionEqual(stringEqual).eq(mappedValue, oldValueMapped)
+    })
+
+    keysAreEqual && appliedFunctionsToKeysAndValues
+  })
 }