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new c423a99 [COLLECTIONS-674] Add drain method to CollectionUtils (#91)
c423a99 is described below
commit c423a9964fa8e17028b378abbe47a50907e6d189
Author: dota17 <50514813+dot...@users.noreply.github.com>
AuthorDate: Fri Nov 1 23:36:24 2019 +0800
[COLLECTIONS-674] Add drain method to CollectionUtils (#91)
* add removeRange&removeCount to CollectionUtils
* modify removeRange&removeCount
---
.../commons/collections4/CollectionUtils.java | 66 +++++++++++++
.../commons/collections4/CollectionUtilsTest.java | 109 +++++++++++++++++++++
2 files changed, 175 insertions(+)
diff --git a/src/main/java/org/apache/commons/collections4/CollectionUtils.java
b/src/main/java/org/apache/commons/collections4/CollectionUtils.java
index 2e6a79f..8afcba2 100644
--- a/src/main/java/org/apache/commons/collections4/CollectionUtils.java
+++ b/src/main/java/org/apache/commons/collections4/CollectionUtils.java
@@ -1792,6 +1792,72 @@ public class CollectionUtils {
}
/**
+ * Removes elements whose index are between startIndex, inclusive and
endIndex,
+ * exclusive in the collection and returns them.
+ * This method modifies the input collections.
+ *
+ * @param <E> the type of object the {@link Collection} contains
+ * @param input the collection will be operated, can't be null
+ * @param startIndex the start index (inclusive) to remove element, can't
be less than 0
+ * @param endIndex the end index (exclusive) to remove, can't be less
than startIndex
+ * @return collection of elements that removed from the input collection
+ * @since 4.5
+ */
+ public static <E> Collection<E> removeRange(final Collection<E> input,
final int startIndex, final int endIndex) {
+ if (null == input) {
+ throw new IllegalArgumentException("The collection can't be
null.");
+ }
+ if (endIndex < startIndex) {
+ throw new IllegalArgumentException("The end index can't be less
than the start index.");
+ }
+ if (input.size() < endIndex) {
+ throw new IndexOutOfBoundsException("The end index can't be
greater than the size of collection.");
+ }
+ return CollectionUtils.removeCount(input, startIndex, endIndex -
startIndex);
+ }
+
+ /**
+ * Removes the specified number of elements from the start index in the
collection and returns them.
+ * This method modifies the input collections.
+ *
+ * @param <E> the type of object the {@link Collection} contains
+ * @param input the collection will be operated, can't be null
+ * @param startIndex the start index (inclusive) to remove element, can't
be less than 0
+ * @param count the specified number to remove, can't be less than 1
+ * @return collection of elements that removed from the input collection
+ * @since 4.5
+ */
+ public static <E> Collection<E> removeCount(final Collection<E> input, int
startIndex, int count) {
+ if (null == input) {
+ throw new IllegalArgumentException("The collection can't be
null.");
+ }
+ if (startIndex < 0) {
+ throw new IndexOutOfBoundsException("The start index can't be less
than 0.");
+ }
+ if (count < 0) {
+ throw new IndexOutOfBoundsException("The count can't be less than
0.");
+ }
+ if (input.size() < startIndex + count) {
+ throw new IndexOutOfBoundsException(
+ "The sum of start index and count can't be greater than
the size of collection.");
+ }
+
+ Collection<E> result = new ArrayList<E>(count);
+ Iterator<E> iterator = input.iterator();
+ while (count > 0) {
+ if (startIndex > 0) {
+ startIndex = startIndex - 1;
+ iterator.next();
+ continue;
+ }
+ count = count - 1;
+ result.add(iterator.next());
+ iterator.remove();
+ }
+ return result;
+ }
+
+ /**
* Removes the elements in <code>remove</code> from
<code>collection</code>. That is, this
* method returns a collection containing all the elements in
<code>c</code>
* that are not in <code>remove</code>. The cardinality of an element
<code>e</code>
diff --git
a/src/test/java/org/apache/commons/collections4/CollectionUtilsTest.java
b/src/test/java/org/apache/commons/collections4/CollectionUtilsTest.java
index 2ef3030..6f4a5b1 100644
--- a/src/test/java/org/apache/commons/collections4/CollectionUtilsTest.java
+++ b/src/test/java/org/apache/commons/collections4/CollectionUtilsTest.java
@@ -1473,6 +1473,115 @@ public class CollectionUtilsTest extends MockTestCase {
}
@Test
+ public void testRemoveRange() {
+ List<Integer> list = new ArrayList<>();
+ list.add(1);
+ Collection<Integer> result = CollectionUtils.removeRange(list, 0, 0);
+ assertEquals(1, list.size());
+ assertEquals(0, result.size());
+
+ list.add(2);
+ list.add(3);
+ result = CollectionUtils.removeRange(list, 1, 3);
+ assertEquals(1, list.size());
+ assertEquals(1, (int) list.get(0));
+ assertEquals(2, result.size());
+ assertTrue(result.contains(2));
+ assertTrue(result.contains(3));
+ }
+
+ @Test(expected=IllegalArgumentException.class)
+ public void testRemoveRangeNull() {
+ Collection<Integer> list = null;
+ Collection result = CollectionUtils.removeRange(list, 0, 0);
+ }
+
+ @Test(expected=IndexOutOfBoundsException.class)
+ public void testRemoveRangeStartIndexNegative() {
+ Collection<Integer> list = new ArrayList<>();
+ list.add(1);
+ Collection result = CollectionUtils.removeRange(list, -1, 1);
+ }
+
+ @Test(expected=IllegalArgumentException.class)
+ public void testRemoveRangeEndIndexNegative() {
+ Collection<Integer> list = new ArrayList<>();
+ list.add(1);
+ Collection result = CollectionUtils.removeRange(list, 0, -1);
+ }
+
+ @Test(expected=IllegalArgumentException.class)
+ public void testRemoveRangeEndLowStart() {
+ Collection<Integer> list = new ArrayList<>();
+ list.add(1);
+ list.add(2);
+ Collection result = CollectionUtils.removeRange(list, 1, 0);
+ }
+
+ @Test(expected=IndexOutOfBoundsException.class)
+ public void testRemoveRangeWrongEndIndex() {
+ Collection<Integer> list = new ArrayList<>();
+ list.add(1);
+ Collection result = CollectionUtils.removeRange(list, 0, 2);
+ }
+
+ @Test
+ public void testRemoveCount() {
+ List<Integer> list = new ArrayList<>();
+ list.add(1);
+ list.add(2);
+ list.add(3);
+ list.add(4);
+
+ Collection<Integer> result = CollectionUtils.removeCount(list, 0, 0);
+ assertEquals(4, list.size());
+ assertEquals(0, result.size());
+
+ result = CollectionUtils.removeCount(list, 0, 1);
+ assertEquals(3, list.size());
+ assertEquals(2, (int) list.get(0));
+ assertEquals(1, result.size());
+ assertTrue(result.contains(1));
+
+ list.add(5);
+ list.add(6);
+ result = CollectionUtils.removeCount(list, 1, 3);
+
+ assertEquals(2, list.size());
+ assertEquals(2, (int) list.get(0));
+ assertEquals(6, (int) list.get(1));
+ assertEquals(3, result.size());
+ assertTrue(result.contains(3));
+ assertTrue(result.contains(4));
+ assertTrue(result.contains(5));
+ }
+
+ @Test(expected=IllegalArgumentException.class)
+ public void testRemoveCountWithNull() {
+ Collection<Integer> list = null;
+ Collection result = CollectionUtils.removeCount(list, 0, 1);
+ }
+
+ @Test(expected=IndexOutOfBoundsException.class)
+ public void testRemoveCountStartNegative() {
+ Collection<Integer> list = new ArrayList<>();
+ Collection result = CollectionUtils.removeCount(list, -1, 1);
+ }
+
+ @Test(expected=IndexOutOfBoundsException.class)
+ public void testRemoveCountNegative() {
+ Collection<Integer> list = new ArrayList<>();
+ Collection result = CollectionUtils.removeCount(list, 0, -1);
+ }
+
+ @Test(expected=IndexOutOfBoundsException.class)
+ public void testRemoveCountWrongCount() {
+ Collection<Integer> list = new ArrayList<>();
+ list.add(1);
+ Collection result = CollectionUtils.removeCount(list, 0, 2);
+ }
+
+ @Test
public void testRemoveAll() {
final List<String> base = new ArrayList<>();
base.add("A");
