> R select(final Iterable inputCollection,
+ final Predicate predicate, R outputCollection, R rejectedCollection) {
+
+ if (inputCollection != null && predicate != null) {
+ for (final O element : inputCollection) {
+ if (predicate.evaluate(element)) {
+ outputCollection.add(element);
+ } else {
+ rejectedCollection.add(element);
+ }
+ }
+ }
+ return outputCollection;
+ }
+
/**
* Selects all elements from inputCollection which don't match the given
* predicate into an output collection.
@@ -966,206 +1007,6 @@ public class CollectionUtils {
return outputCollection;
}
- /**
- * Partitions all elements from inputCollection into separate output collections,
- * based on the evaluation of the given predicate.
- *
- * For each predicate, the result will contain a list holding all elements of the
- * input collection matching the predicate. The last list will hold all elements
- * which didn't match any predicate:
- *
- * [C1, R] = partition(I, P1) with
- * I = input collection
- * P1 = first predicate
- * C1 = collection of elements matching P1
- * R = collection of elements rejected by all predicates
- *
- *
- * If the input collection is null, an empty list will be returned.
- * If the input predicate is null, all elements of the input collection
- * will be added to the rejected collection.
- *
- * Example: for an input list [1, 2, 3, 4, 5] calling partition with a predicate [x < 3]
- * will result in the following output: [[1, 2], [3, 4, 5]].
- *
- * @param the type of object the {@link Iterable} contains
- * @param inputCollection the collection to get the input from, may be null
- * @param predicate the predicate to use, may be null
- * @return a list containing the output collections
- * @since 4.1
- */
- public static List> partition(final Iterable inputCollection,
- final Predicate predicate) {
-
- @SuppressWarnings({ "unchecked", "rawtypes" }) // safe
- final Factory> factory = FactoryUtils.instantiateFactory((Class) ArrayList.class);
- @SuppressWarnings("unchecked") // safe
- final Predicate[] predicates = new Predicate[] { predicate };
- return partition(inputCollection, factory, predicates);
- }
-
- /**
- * Partitions all elements from inputCollection into an output and rejected collection,
- * based on the evaluation of the given predicate.
- *
- * Elements matching the predicate are added to the outputCollection,
- * all other elements are added to the rejectedCollection.
- *
- * If the input predicate is null, no elements are added to
- * outputCollection or rejectedCollection.
- *
- * Note: calling the method is equivalent to the following code snippet:
- *
- * select(inputCollection, predicate, outputCollection);
- * selectRejected(inputCollection, predicate, rejectedCollection);
- *
- *
- * @param the type of object the {@link Iterable} contains
- * @param the type of the output {@link Collection}
- * @param inputCollection the collection to get the input from, may be null
- * @param predicate the predicate to use, may be null
- * @param outputCollection the collection to output selected elements into, may not be null if the
- * inputCollection and predicate are not null
- * @param rejectedCollection the collection to output rejected elements into, may not be null if the
- * inputCollection or predicate are not null
- * @since 4.1
- */
- public static > void partition(final Iterable inputCollection,
- final Predicate predicate, R outputCollection, R rejectedCollection) {
-
- if (inputCollection != null && predicate != null) {
- for (final O element : inputCollection) {
- if (predicate.evaluate(element)) {
- outputCollection.add(element);
- } else {
- rejectedCollection.add(element);
- }
- }
- }
- }
-
- /**
- * Partitions all elements from inputCollection into separate output collections,
- * based on the evaluation of the given predicates.
- *
- * For each predicate, the result will contain a list holding all elements of the
- * input collection matching the predicate. The last list will hold all elements
- * which didn't match any predicate:
- *
- * [C1, C2, R] = partition(I, P1, P2) with
- * I = input collection
- * P1 = first predicate
- * P2 = second predicate
- * C1 = collection of elements matching P1
- * C2 = collection of elements matching P2
- * R = collection of elements rejected by all predicates
- *
- *
- * Note: elements are only added to the output collection of the first matching
- * predicate, determined by the order of arguments.
- *
- * If the input collection is null, an empty list will be returned.
- * If the input predicate is null, all elements of the input collection
- * will be added to the rejected collection.
- *
- * Example: for an input list [1, 2, 3, 4, 5] calling partition with predicates [x < 3]
- * and [x < 5] will result in the following output: [[1, 2], [3, 4], [5]].
- *
- * @param the type of object the {@link Iterable} contains
- * @param inputCollection the collection to get the input from, may be null
- * @param predicates the predicates to use, may be null
- * @return a list containing the output collections
- * @since 4.1
- */
- public static List> partition(final Iterable inputCollection,
- final Predicate... predicates) {
-
- @SuppressWarnings({ "unchecked", "rawtypes" }) // safe
- final Factory> factory = FactoryUtils.instantiateFactory((Class) ArrayList.class);
- return partition(inputCollection, factory, predicates);
- }
-
- /**
- * Partitions all elements from inputCollection into separate output collections,
- * based on the evaluation of the given predicates.
- *
- * For each predicate, the returned list will contain a collection holding
- * all elements of the input collection matching the predicate. The last collection
- * contained in the list will hold all elements which didn't match any predicate:
- *
- * [C1, C2, R] = partition(I, P1, P2) with
- * I = input collection
- * P1 = first predicate
- * P2 = second predicate
- * C1 = collection of elements matching P1
- * C2 = collection of elements matching P2
- * R = collection of elements rejected by all predicates
- *
- *
- * Note: elements are only added to the output collection of the first matching
- * predicate, determined by the order of arguments.
- *
- * If the input collection is null, an empty list will be returned.
- * If no predicates have been provided, all elements of the input collection
- * will be added to the rejected collection.
- *
- * Example: for an input list [1, 2, 3, 4, 5] calling partition with predicates [x < 3]
- * and [x < 5] will result in the following output: [[1, 2], [3, 4], [5]].
- *
- * @param the type of object the {@link Iterable} contains
- * @param the type of the output {@link Collection}
- * @param inputCollection the collection to get the input from, may be null
- * @param partitionFactory the factory used to create the output collections
- * @param predicates the predicates to use, may be empty
- * @return a list containing the output collections
- * @since 4.1
- */
- public static > List partition(final Iterable inputCollection,
- final Factory partitionFactory, final Predicate... predicates) {
-
- if (inputCollection == null) {
- return Collections.emptyList();
- }
-
- if (predicates == null || predicates.length < 1) {
- // return the entire input collection as a single partition
- final R singlePartition = partitionFactory.create();
- select(inputCollection, PredicateUtils.truePredicate(), singlePartition);
- return Collections.singletonList(singlePartition);
- }
-
- // create the empty partitions
- final int numberOfPredicates = predicates.length;
- final int numberOfPartitions = numberOfPredicates + 1;
- final List partitions = new ArrayList(numberOfPartitions);
- for (int i = 0; i < numberOfPartitions; ++i) {
- partitions.add(partitionFactory.create());
- }
-
- // for each element in inputCollection:
- // find the first predicate that evaluates to true.
- // if there is a predicate, add the element to the corresponding partition.
- // if there is no predicate, add it to the last, catch-all partition.
- for (final O element : inputCollection) {
- boolean elementAssigned = false;
- for (int i = 0; i < numberOfPredicates; ++i) {
- if (predicates[i].evaluate(element)) {
- partitions.get(i).add(element);
- elementAssigned = true;
- break;
- }
- }
-
- if (!elementAssigned) {
- // no predicates evaluated to true
- // add element to last partition
- partitions.get(numberOfPredicates).add(element);
- }
- }
-
- return partitions;
- }
-
/**
* Returns a new Collection containing all elements of the input collection
* transformed by the given transformer.
diff --git a/src/main/java/org/apache/commons/collections4/IterableUtils.java b/src/main/java/org/apache/commons/collections4/IterableUtils.java
index 015aad898..9a04619bf 100644
--- a/src/main/java/org/apache/commons/collections4/IterableUtils.java
+++ b/src/main/java/org/apache/commons/collections4/IterableUtils.java
@@ -16,7 +16,9 @@
*/
package org.apache.commons.collections4;
+import java.util.ArrayList;
import java.util.Collection;
+import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
@@ -680,6 +682,178 @@ public class IterableUtils {
}
}
+ /**
+ * Partitions all elements from iterable into separate output collections,
+ * based on the evaluation of the given predicate.
+ *
+ * For each predicate, the result will contain a list holding all elements of the
+ * input iterable matching the predicate. The last list will hold all elements
+ * which didn't match any predicate:
+ *
+ * [C1, R] = partition(I, P1) with
+ * I = input
+ * P1 = first predicate
+ * C1 = collection of elements matching P1
+ * R = collection of elements rejected by all predicates
+ *
+ *
+ * If the input iterable is null, the same is returned as for an
+ * empty iterable.
+ *
+ * Example: for an input list [1, 2, 3, 4, 5] calling partition with a predicate [x < 3]
+ * will result in the following output: [[1, 2], [3, 4, 5]].
+ *
+ * @param the type of object the {@link Iterable} contains
+ * @param iterable the iterable to partition, may be null
+ * @param predicate the predicate to use, may not be null
+ * @return a list containing the output collections
+ * @throws NullPointerException if predicate is null
+ */
+ public static List> partition(final Iterable iterable,
+ final Predicate predicate) {
+ if (predicate == null) {
+ throw new NullPointerException("Predicate must not be null.");
+ }
+ @SuppressWarnings({ "unchecked", "rawtypes" }) // safe
+ final Factory> factory = FactoryUtils.instantiateFactory((Class) ArrayList.class);
+ @SuppressWarnings("unchecked") // safe
+ final Predicate[] predicates = new Predicate[] { predicate };
+ return partition(iterable, factory, predicates);
+ }
+
+ /**
+ * Partitions all elements from iterable into separate output collections,
+ * based on the evaluation of the given predicates.
+ *
+ * For each predicate, the result will contain a list holding all elements of the
+ * input iterable matching the predicate. The last list will hold all elements
+ * which didn't match any predicate:
+ *
+ * [C1, C2, R] = partition(I, P1, P2) with
+ * I = input
+ * P1 = first predicate
+ * P2 = second predicate
+ * C1 = collection of elements matching P1
+ * C2 = collection of elements matching P2
+ * R = collection of elements rejected by all predicates
+ *
+ *
+ * Note: elements are only added to the output collection of the first matching
+ * predicate, determined by the order of arguments.
+ *
+ * If the input iterable is null, the same is returned as for an
+ * empty iterable.
+ *
+ * Example: for an input list [1, 2, 3, 4, 5] calling partition with predicates [x < 3]
+ * and [x < 5] will result in the following output: [[1, 2], [3, 4], [5]].
+ *
+ * @param the type of object the {@link Iterable} contains
+ * @param iterable the collection to get the input from, may be null
+ * @param predicates the predicates to use, may not be null
+ * @return a list containing the output collections
+ * @throws NullPointerException if any predicate is null
+ */
+ public static List> partition(final Iterable iterable,
+ final Predicate... predicates) {
+
+ @SuppressWarnings({ "unchecked", "rawtypes" }) // safe
+ final Factory> factory = FactoryUtils.instantiateFactory((Class) ArrayList.class);
+ return partition(iterable, factory, predicates);
+ }
+
+ /**
+ * Partitions all elements from iterable into separate output collections,
+ * based on the evaluation of the given predicates.
+ *
+ * For each predicate, the returned list will contain a collection holding
+ * all elements of the input iterable matching the predicate. The last collection
+ * contained in the list will hold all elements which didn't match any predicate:
+ *
+ * [C1, C2, R] = partition(I, P1, P2) with
+ * I = input
+ * P1 = first predicate
+ * P2 = second predicate
+ * C1 = collection of elements matching P1
+ * C2 = collection of elements matching P2
+ * R = collection of elements rejected by all predicates
+ *
+ *
+ * Note: elements are only added to the output collection of the first matching
+ * predicate, determined by the order of arguments.
+ *
+ * If the input iterable is null, the same is returned as for an
+ * empty iterable.
+ * If no predicates have been provided, all elements of the input collection
+ * will be added to the rejected collection.
+ *
+ * Example: for an input list [1, 2, 3, 4, 5] calling partition with predicates [x < 3]
+ * and [x < 5] will result in the following output: [[1, 2], [3, 4], [5]].
+ *
+ * @param the type of object the {@link Iterable} contains
+ * @param the type of the output {@link Collection}
+ * @param iterable the collection to get the input from, may be null
+ * @param partitionFactory the factory used to create the output collections
+ * @param predicates the predicates to use, may not be null
+ * @return a list containing the output collections
+ * @throws NullPointerException if any predicate is null
+ */
+ public static > List partition(final Iterable iterable,
+ final Factory partitionFactory, final Predicate... predicates) {
+
+ if (iterable == null) {
+ final Iterable empty = emptyIterable();
+ return partition(empty, partitionFactory, predicates);
+ }
+
+ if (predicates == null) {
+ throw new NullPointerException("Predicates must not be null.");
+ }
+
+ for (Predicate p : predicates) {
+ if (p == null) {
+ throw new NullPointerException("Predicate must not be null.");
+ }
+ }
+
+ if (predicates.length < 1) {
+ // return the entire input collection as a single partition
+ final R singlePartition = partitionFactory.create();
+ CollectionUtils.addAll(singlePartition, iterable);
+ return Collections.singletonList(singlePartition);
+ }
+
+ // create the empty partitions
+ final int numberOfPredicates = predicates.length;
+ final int numberOfPartitions = numberOfPredicates + 1;
+ final List partitions = new ArrayList(numberOfPartitions);
+ for (int i = 0; i < numberOfPartitions; ++i) {
+ partitions.add(partitionFactory.create());
+ }
+
+ // for each element in inputCollection:
+ // find the first predicate that evaluates to true.
+ // if there is a predicate, add the element to the corresponding partition.
+ // if there is no predicate, add it to the last, catch-all partition.
+ for (final O element : iterable) {
+ boolean elementAssigned = false;
+ for (int i = 0; i < numberOfPredicates; ++i) {
+ if (predicates[i].evaluate(element)) {
+ partitions.get(i).add(element);
+ elementAssigned = true;
+ break;
+ }
+ }
+
+ if (!elementAssigned) {
+ // no predicates evaluated to true
+ // add element to last partition
+ partitions.get(numberOfPredicates).add(element);
+ }
+ }
+
+ return partitions;
+ }
+
/**
* Gets a new list with the contents of the provided iterable.
*
diff --git a/src/test/java/org/apache/commons/collections4/CollectionUtilsTest.java b/src/test/java/org/apache/commons/collections4/CollectionUtilsTest.java
index 597dd2400..931ea8f2e 100644
--- a/src/test/java/org/apache/commons/collections4/CollectionUtilsTest.java
+++ b/src/test/java/org/apache/commons/collections4/CollectionUtilsTest.java
@@ -1070,12 +1070,6 @@ public class CollectionUtilsTest extends MockTestCase {
}
};
- private static Predicate EVEN = new Predicate() {
- public boolean evaluate(final Number input) {
- return input.intValue() % 2 == 0;
- }
- };
-
//Up to here
@Test
public void filter() {
@@ -1170,6 +1164,34 @@ public class CollectionUtilsTest extends MockTestCase {
assertEquals(2, output2.iterator().next());
}
+ @Test
+ public void selectWithOutputCollections() {
+ List input = new ArrayList();
+ input.add(1);
+ input.add(2);
+ input.add(3);
+ input.add(4);
+
+ List output = new ArrayList();
+ List rejected = new ArrayList();
+
+ CollectionUtils.select(input, EQUALS_TWO, output, rejected);
+
+ // output contains 2
+ assertEquals(1, output.size());
+ assertEquals(2, CollectionUtils.extractSingleton(output).intValue());
+
+ // rejected contains 1, 3, and 4
+ Integer[] expected = {1, 3, 4};
+ Assert.assertArrayEquals(expected, rejected.toArray());
+
+ output.clear();
+ rejected.clear();
+ CollectionUtils.select((List) null, EQUALS_TWO, output, rejected);
+ assertTrue(output.isEmpty());
+ assertTrue(rejected.isEmpty());
+ }
+
@Test
public void selectRejected() {
final List list = new ArrayList();
@@ -1189,89 +1211,6 @@ public class CollectionUtilsTest extends MockTestCase {
assertTrue(output1.contains(4L));
}
- @SuppressWarnings("unchecked")
- @Test
- public void partition() {
- List input = new ArrayList();
- input.add(1);
- input.add(2);
- input.add(3);
- input.add(4);
- List> partitions = CollectionUtils.partition(input, EQUALS_TWO);
- assertEquals(2, partitions.size());
-
- // first partition contains 2
- Collection partition = partitions.get(0);
- assertEquals(1, partition.size());
- assertEquals(2, CollectionUtils.extractSingleton(partition).intValue());
-
- // second partition contains 1, 3, and 4
- Integer[] expected = {1, 3, 4};
- partition = partitions.get(1);
- Assert.assertArrayEquals(expected, partition.toArray());
-
- partitions = CollectionUtils.partition((List) null, EQUALS_TWO);
- assertTrue(partitions.isEmpty());
-
- partitions = CollectionUtils.partition(input);
- assertEquals(1, partitions.size());
- assertEquals(input, partitions.get(0));
- }
-
- @Test
- public void partitionWithOutputCollections() {
- List input = new ArrayList();
- input.add(1);
- input.add(2);
- input.add(3);
- input.add(4);
-
- List output = new ArrayList();
- List rejected = new ArrayList();
-
- CollectionUtils.partition(input, EQUALS_TWO, output, rejected);
-
- // output contains 2
- assertEquals(1, output.size());
- assertEquals(2, CollectionUtils.extractSingleton(output).intValue());
-
- // rejected contains 1, 3, and 4
- Integer[] expected = {1, 3, 4};
- Assert.assertArrayEquals(expected, rejected.toArray());
-
- output.clear();
- rejected.clear();
- CollectionUtils.partition((List) null, EQUALS_TWO, output, rejected);
- assertTrue(output.isEmpty());
- assertTrue(rejected.isEmpty());
- }
-
- @Test
- public void partitionMultiplePredicates() {
- List input = new ArrayList();
- input.add(1);
- input.add(2);
- input.add(3);
- input.add(4);
- @SuppressWarnings("unchecked")
- List> partitions = CollectionUtils.partition(input, EQUALS_TWO, EVEN);
-
- // first partition contains 2
- Collection partition = partitions.get(0);
- assertEquals(1, partition.size());
- assertEquals(2, partition.iterator().next().intValue());
-
- // second partition contains 4
- partition = partitions.get(1);
- assertEquals(1, partition.size());
- assertEquals(4, partition.iterator().next().intValue());
-
- // third partition contains 1 and 3
- Integer[] expected = {1, 3};
- partition = partitions.get(2);
- Assert.assertArrayEquals(expected, partition.toArray());
- }
-
@Test
public void collect() {
final Transformer transformer = TransformerUtils.constantTransformer(2L);
diff --git a/src/test/java/org/apache/commons/collections4/IterableUtilsTest.java b/src/test/java/org/apache/commons/collections4/IterableUtilsTest.java
index 73daa880c..5dea179b6 100644
--- a/src/test/java/org/apache/commons/collections4/IterableUtilsTest.java
+++ b/src/test/java/org/apache/commons/collections4/IterableUtilsTest.java
@@ -26,6 +26,7 @@ import java.util.LinkedList;
import java.util.List;
import org.apache.commons.collections4.bag.HashBag;
+import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
@@ -89,6 +90,12 @@ public class IterableUtilsTest {
}
};
+ private static Predicate EVEN = new Predicate() {
+ public boolean evaluate(final Number input) {
+ return input.intValue() % 2 == 0;
+ }
+ };
+
// -----------------------------------------------------------------------
@Test
public void apply() {
@@ -269,6 +276,76 @@ public class IterableUtilsTest {
IterableUtils.get(bag, 1);
}
+ @SuppressWarnings("unchecked")
+ @Test
+ public void partition() {
+ List input = new ArrayList();
+ input.add(1);
+ input.add(2);
+ input.add(3);
+ input.add(4);
+ List> partitions = IterableUtils.partition(input, EQUALS_TWO);
+ assertEquals(2, partitions.size());
+
+ // first partition contains 2
+ Collection partition = partitions.get(0);
+ assertEquals(1, partition.size());
+ assertEquals(2, CollectionUtils.extractSingleton(partition).intValue());
+
+ // second partition contains 1, 3, and 4
+ Integer[] expected = {1, 3, 4};
+ partition = partitions.get(1);
+ Assert.assertArrayEquals(expected, partition.toArray());
+
+ partitions = IterableUtils.partition((List) null, EQUALS_TWO);
+ assertEquals(2, partitions.size());
+ assertTrue(partitions.get(0).isEmpty());
+ assertTrue(partitions.get(1).isEmpty());
+
+ partitions = IterableUtils.partition(input);
+ assertEquals(1, partitions.size());
+ assertEquals(input, partitions.get(0));
+
+ try {
+ IterableUtils.partition(input, (Predicate) null);
+ fail("expecting NullPointerException");
+ } catch (NullPointerException npe) {
+ // expected
+ }
+ }
+
+ @SuppressWarnings("unchecked")
+ @Test
+ public void partitionMultiplePredicates() {
+ List input = new ArrayList();
+ input.add(1);
+ input.add(2);
+ input.add(3);
+ input.add(4);
+ List> partitions = IterableUtils.partition(input, EQUALS_TWO, EVEN);
+
+ // first partition contains 2
+ Collection partition = partitions.get(0);
+ assertEquals(1, partition.size());
+ assertEquals(2, partition.iterator().next().intValue());
+
+ // second partition contains 4
+ partition = partitions.get(1);
+ assertEquals(1, partition.size());
+ assertEquals(4, partition.iterator().next().intValue());
+
+ // third partition contains 1 and 3
+ Integer[] expected = {1, 3};
+ partition = partitions.get(2);
+ Assert.assertArrayEquals(expected, partition.toArray());
+
+ try {
+ IterableUtils.partition(input, EQUALS_TWO, null);
+ } catch (NullPointerException npe) {
+ // expected
+ }
+ }
+
@Test
public void testToString() {
String result = IterableUtils.toString(iterableA);