add sort (ascending) method

primitiveCollections/src/main/java/org/lucares/collections/IntList.java

@@ -1,5 +1,6 @@
 package org.lucares.collections;
 
+import java.util.Arrays;
 import java.util.List;
 
 /**
@@ -249,6 +250,13 @@ public class IntList {
 		return get(0, index);
 	}
 
+	/**
+	 * Sorts the list into ascending order.
+	 */
+	public void sort() {
+		Arrays.sort(data, 0, index);
+	}
+
 	private void ensureCapacity(final int newElements) {
 
 		final int requiredCapacity = index + newElements;

primitiveCollections/src/test/java/org/lucares/collections/IntListTest.java

@@ -386,6 +386,17 @@ public class IntListTest {
 		Assert.assertNotEquals(a.hashCode(), b.hashCode());
 	}
 
+	@Test
+	public void testSort() {
+		final IntList list = new IntList();
+
+		list.addAll(4, 2, 3, 1);
+		list.sort();
+
+		final int[] expectedE = new int[] { 1, 2, 3, 4 };
+		Assert.assertArrayEquals(expectedE, list.toArray());
+	}
+
 	private int[] removeElements(final int[] data, final int... removedElements) {
 		final int[] result = new int[data.length - removedElements.length];
 		final List<Integer> blacklist = Arrays.stream(removedElements).boxed().collect(Collectors.toList());