Deprecate Transformer in favor of java.util.function.Function

src/changes/changes.xml

@@ -29,6 +29,7 @@
      <action type="update" dev="ggregory" due-to="Gary Gregory">Deprecate Closure in favor of java.util.function.Consumer.</action>
      <action type="update" dev="ggregory" due-to="Gary Gregory">Deprecate Factory in favor of java.util.function.Supplier.</action>
      <action type="update" dev="ggregory" due-to="Gary Gregory">Deprecate Predicate in favor of java.util.function.Predicate.</action>
+     <action type="update" dev="ggregory" due-to="Gary Gregory">Deprecate Transformer in favor of java.util.function.Function.</action>
      <!-- UPDATE -->
      <action type="update" dev="ggregory" due-to="Dependabot">Bump org.apache.commons:commons-parent from 67 to 69 #473.</action>
      <action type="update" dev="ggregory" due-to="Dependabot">Bump tests commons-io:commons-io from 2.16.0 to 2.16.1 #475 .</action>

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

@@ -16,6 +16,8 @@
  */
 package org.apache.commons.collections4;
 
+import java.util.function.Function;
+
 /**
  * Defines a functor interface implemented by classes that transform one
  * object into another.
@@ -31,13 +33,19 @@ package org.apache.commons.collections4;
  * cloning and returning the string value.
  * </p>
  *
- * @param <I> the input type to the transformer
+ * @param <T> the input type to the transformer
- * @param <O> the output type from the transformer
+ * @param <R> the output type from the transformer
  *
  * @since 1.0
+ * @deprecated Use {@link Function}.
  */
-@FunctionalInterface
+@Deprecated
-public interface Transformer<I, O> {
+public interface Transformer<T, R> extends Function<T, R> {
+
+    @Override
+    default R apply(final T t) {
+        return transform(t);
+    }
 
     /**
      * Transforms the input object (leaving it unchanged) into some output object.
@@ -48,6 +56,6 @@ public interface Transformer<I, O> {
      * @throws IllegalArgumentException (runtime) if the input is invalid
      * @throws FunctorException (runtime) if the transform cannot be completed
      */
-    O transform(I input);
+    R transform(T input);
 
 }

src/main/java/org/apache/commons/collections4/comparators/FixedOrderComparator.java

@@ -212,7 +212,7 @@ public class FixedOrderComparator<T> implements Comparator<T>, Serializable {
         if (getClass() != obj.getClass()) {
             return false;
         }
-        FixedOrderComparator other = (FixedOrderComparator) obj;
+        FixedOrderComparator<?> other = (FixedOrderComparator<?>) obj;
         return counter == other.counter && isLocked == other.isLocked && Objects.equals(map, other.map) && unknownObjectBehavior == other.unknownObjectBehavior;
     }
 

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

@@ -70,7 +70,7 @@ public class ClosureUtilsTest {
     public void testChainedClosure() {
         MockClosure<Object> a = new MockClosure<>();
         MockClosure<Object> b = new MockClosure<>();
-        ClosureUtils.chainedClosure(a, b).execute(null);
+        ClosureUtils.chainedClosure(a, b).accept(null);
         assertEquals(1, a.count);
         assertEquals(1, b.count);
 

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

@@ -149,7 +149,7 @@ public class FactoryUtilsTest {
     public void testInstantiateFactorySimple() {
         final Factory<Mock3> factory = FactoryUtils.instantiateFactory(Mock3.class);
         assertNotNull(factory);
-        Mock3 created = factory.create();
+        Mock3 created = factory.get();
         assertEquals(0, created.getValue());
         created = factory.create();
         assertEquals(1, created.getValue());

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

@@ -57,9 +57,9 @@ public class PredicateUtilsTest extends AbstractPredicateTest {
     @SuppressWarnings("unchecked")
     public void testAllPredicate() {
         assertPredicateTrue(AllPredicate.allPredicate(), null);
-        assertTrue(AllPredicate.allPredicate(truePredicate(), truePredicate(), truePredicate()).evaluate(null));
+        assertTrue(AllPredicate.allPredicate(truePredicate(), truePredicate(), truePredicate()).test(null));
-        assertFalse(AllPredicate.allPredicate(truePredicate(), FalsePredicate.falsePredicate(), truePredicate()).evaluate(null));
+        assertFalse(AllPredicate.allPredicate(truePredicate(), FalsePredicate.falsePredicate(), truePredicate()).test(null));
-        assertFalse(AllPredicate.allPredicate(FalsePredicate.falsePredicate(), FalsePredicate.falsePredicate(), truePredicate()).evaluate(null));
+        assertFalse(AllPredicate.allPredicate(FalsePredicate.falsePredicate(), FalsePredicate.falsePredicate(), truePredicate()).test(null));
         assertFalse(AllPredicate.allPredicate(FalsePredicate.falsePredicate(), FalsePredicate.falsePredicate(), FalsePredicate.falsePredicate()).evaluate(null));
         final Collection<Predicate<Object>> coll = new ArrayList<>();
         coll.add(TruePredicate.truePredicate());

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

@@ -55,7 +55,9 @@ public class TransformerUtilsTest {
     public void testChainedTransformer() {
         final Transformer<Object, Object> a = TransformerUtils.<Object, Object>constantTransformer("A");
         final Transformer<Object, Object> b = TransformerUtils.constantTransformer((Object) "B");
-
+        assertEquals("A", TransformerUtils.chainedTransformer(b, a).apply(null));
+        assertEquals("B", TransformerUtils.chainedTransformer(a, b).apply(null));
+        assertEquals("A", TransformerUtils.chainedTransformer(b, a).apply(null));
         assertEquals("A", TransformerUtils.chainedTransformer(b, a).transform(null));
         assertEquals("B", TransformerUtils.chainedTransformer(a, b).transform(null));
         assertEquals("A", TransformerUtils.chainedTransformer(b, a).transform(null));