Merge pull request #103 from Umutayb/list-partition-utility

Update ArrayUtilities.java

Author: Umutayb

src/main/java/utils/arrays/ArrayUtilities.java

@@ -1,5 +1,6 @@
 package utils.arrays;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Random;
 
@@ -40,5 +41,41 @@ public static <ItemType> ItemType getRandomItemFrom(List<ItemType> items) {
     public static <ItemType> boolean isLastMemberOf(List<ItemType> items, ItemType member){
         return items.indexOf(member) == (items.size() - 1);
     }
+
+    /**
+     * Splits a given list into partitions and returns a specific partition based on the partition index.
+     *
+     * This method uses stream filtering to find and return the elements that belong to the requested partition.
+     * The partition index is 0-based.
+     *
+     * @param <T> The type of elements in the list.
+     * @param originalList The original list to be partitioned.
+     * @param partitionSize The size of each partition.
+     * @param partitionIndex The index of the partition to retrieve (0-based index).
+     * @return A list containing the elements from the specified partition.
+     * @throws IndexOutOfBoundsException If the partitionIndex is out of bounds (negative or too large).
+     */
+    public static <T> List<T> getListPartition(List<T> originalList, int partitionSize, int partitionIndex){
+        int partitionBottomLimit = partitionSize * partitionIndex;
+        return originalList.stream().filter(item -> {
+            int itemIndex = originalList.indexOf(item);
+            return partitionBottomLimit <= itemIndex && itemIndex < partitionSize + partitionBottomLimit;
+        }).toList();
+    }
+
+    /**
+     * Calculates the total number of partitions needed to divide a list of a given size into partitions
+     * of the specified size.
+     *
+     * If there are leftover elements after dividing the list, an extra partition is counted.
+     *
+     * @param listSize The total number of elements in the list.
+     * @param partitionSize The size of each partition.
+     * @return The number of partitions required to divide the list.
+     */
+    public static int getPartitionCount(int listSize, int partitionSize){
+        int partitionCount = listSize / partitionSize;
+        return listSize % partitionCount == 0 ? partitionCount : partitionCount + 1;
+    }
 }
 

src/test/java/AppTest.java

@@ -19,7 +19,7 @@
 import java.util.List;
 import java.util.regex.Pattern;
 
-import static utils.arrays.ArrayUtilities.isLastMemberOf;
+import static utils.arrays.ArrayUtilities.*;
 import static utils.email.EmailUtilities.Inbox.EmailField.CONTENT;
 import static utils.email.EmailUtilities.Inbox.EmailField.SUBJECT;
 import static utils.MappingUtilities.Json.*;
@@ -241,12 +241,39 @@ public void setFieldTest() {
                 expectedFieldValue,
                 pet.getName()
         );
-        printer.success("The setFieldTest() test passed!");
+        printer.success("The setFieldTest() test pass!");
     }
 
     @Test
     public void lastItemOfTest() {
         List<Integer> integers = List.of(1, 2, 3, 4, 5);
         Assert.assertTrue("Integer was not the last member!", isLastMemberOf(integers, 5));
+        printer.success("The lastItemOfTest() test pass!");
+    }
+
+    @Test
+    public void partitionTest() {
+        List<Integer> integers = List.of(1, 2, 3, 4, 5);
+        List<List<Integer>> partitionLists = List.of(
+                List.of(1,2),
+                List.of(3,4),
+                List.of(5)
+        );
+        for (int i = 0; i < getPartitionCount(integers.size(), 2); i++) {
+            List<Integer> partition = getListPartition(integers, 2, i);
+            Assert.assertEquals(partition, partitionLists.get(i));
+        }
+        printer.success("The partitionTest() test pass!");
+    }
+
+    @Test
+    public void partitionCountTest() {
+        List<Integer> integers = List.of(1, 2, 3, 4, 5);
+        Assert.assertEquals(
+                "The getPartitionCount() method returns an incorrect value!",
+                3,
+                getPartitionCount(integers.size(), 2)
+        );
+        printer.success("The partitionCountTest() test pass!");
     }
 }