BAEL-5623 reverse list article (#12253)

* reverse list article

* fix the package

core-java-modules/core-java-collections-list-4/src/main/java/com/baeldung/list/reverse/ReverseArrayList.java

@@ -0,0 +1,23 @@
+package com.baeldung.list.reverse;
+
+import java.util.List;
+
+public class ReverseArrayList {
+    private ReverseArrayList() {
+        throw new RuntimeException("This class cannot be instantiated.");
+    }
+
+    public static <T> void reverseWithRecursion(List<T> list) {
+        if (list.size() > 1) {
+            T value = list.remove(0);
+            reverseWithRecursion(list);
+            list.add(value);
+        }
+    }
+
+    public static <T> void reverseWithLoop(List<T> list) {
+        for (int i = 0, j = list.size() - 1; i < j; i++) {
+            list.add(i, list.remove(j));
+        }
+    }
+}

core-java-modules/core-java-collections-list-4/src/test/java/com/baeldung/list/reverse/ReverseArrayListUnitTest.java

@@ -0,0 +1,46 @@
+package com.baeldung.list.reverse;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+class ReverseArrayListUnitTest {
+
+    private static final List<Integer> EXPECTED = new ArrayList<>(Arrays.asList(7, 6, 5, 4, 3, 2, 1));
+
+    @Test
+    void givenArrayList_whenCallReverseMethod_thenListReversedInPlace() {
+        List<Integer> aList = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5, 6, 7));
+        Collections.reverse(aList);
+        assertThat(aList).isEqualTo(EXPECTED);
+    }
+
+    @Test
+    void givenArrayList_whenCallReverseMethod_thenListReversedAsaNewList() {
+        List<Integer> originalList = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5, 6, 7));
+        List<Integer> aNewList = new ArrayList<>(originalList);
+        Collections.reverse(aNewList);
+
+        assertThat(aNewList).isNotEqualTo(originalList)
+            .isEqualTo(EXPECTED);
+    }
+
+    @Test
+    void givenArrayList_whenCallReverseWithRecur_thenListReversedInPlace() {
+        List<Integer> aList = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5, 6, 7));
+        ReverseArrayList.reverseWithRecursion(aList);
+        assertThat(aList).isEqualTo(EXPECTED);
+    }
+
+    @Test
+    void givenArrayList_whenCallReverseWithLoop_thenListReversedInPlace() {
+        List<Integer> aList = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5, 6, 7));
+        ReverseArrayList.reverseWithLoop(aList);
+        assertThat(aList).isEqualTo(EXPECTED);
+    }
+}