feat: Add ToggleNthBit algo with JUnit tests

Author: Tanmay-Singh3004

DIRECTORY.md

@@ -45,6 +45,7 @@
             * [SingleBitOperations](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/SingleBitOperations.java)
             * [SingleElement](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/SingleElement.java)
             * [SwapAdjacentBits](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/SwapAdjacentBits.java)
+            * [ToggleNthBit](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/ToggleNthBit.java)
             * [TwosComplement](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/TwosComplement.java)
           * ciphers
             * a5
@@ -676,6 +677,7 @@
             * [SingleBitOperationsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/SingleBitOperationsTest.java)
             * [SingleElementTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/SingleElementTest.java)
             * [SwapAdjacentBitsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/SwapAdjacentBitsTest.java)
+            * [ToggleNthBitTest](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/ToggleNthBitTest.java)
             * [TwosComplementTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/TwosComplementTest.java)
           * ciphers
             * a5

src/main/java/com/thealgorithms/bitmanipulation/ToggleNthBit.java

@@ -0,0 +1,46 @@
+package com.thealgorithms.bitmanipulation;
+
+/**
+ * <pre>
+ * This class provides a method to toggle the nth bit of an integer.
+ *
+ * Toggling a bit means flipping it: changing a 0 to a 1 or a 1 to a 0.
+ *
+ * The algorithm works as follows:
+ *
+ * Let's say we have an integer x and we want to toggle its nth bit.
+ *
+ * Step 1: Create a bitmask with a 1 at the nth position.
+ * - Example: If n = 2, the bitmask will be 1 << 2 = 4 (0100 in binary).
+ *
+ * Step 2: XOR the integer x with the bitmask.
+ * - Example: If x = 5 (0101 in binary) and the bitmask is 4 (0100 in binary),
+ *   then x ^ bitmask = 5 ^ 4 = 1 (0001 in binary).
+ *
+ * After these two steps, the nth bit of x is toggled.
+ *
+ * For more information, refer to the
+ * <a href="https://en.wikipedia.org/wiki/Bit_manipulation">Bit manipulation</a>.
+ *
+ * <b>Example usage:</b>
+ * <code>
+ * int result = ToggleNthBit.toggleNthBit(5, 2);<br>
+ * System.out.println("Result after toggling 2nd bit: " + result);
+ * </code>
+ * </pre>
+ */
+public final class ToggleNthBit {
+    private ToggleNthBit() {
+    }
+
+    /**
+     * Toggles the nth bit of an integer.
+     *
+     * @param x the integer whose nth bit is to be toggled
+     * @param n the position of the bit to be toggled (0-based index)
+     * @return the integer with the nth bit toggled
+     */
+    public static int toggleNthBit(int x, int n) {
+        return x ^ (1 << n);
+    }
+}

src/test/java/com/thealgorithms/bitmanipulation/ToggleNthBitTest.java

@@ -0,0 +1,48 @@
+package com.thealgorithms.bitmanipulation;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Unit tests for the ToggleNthBit class.
+ */
+public class ToggleNthBitTest {
+
+    /**
+     * Test the toggleNthBit method with a positive number.
+     */
+    @Test
+    public void testToggleNthBitPositive() {
+        int result = ToggleNthBit.toggleNthBit(5, 2);
+        assertEquals(1, result); // 5 (0101) with 2nd bit toggled becomes 1 (0001)
+    }
+
+    /**
+     * Test the toggleNthBit method with a negative number.
+     */
+    @Test
+    public void testToggleNthBitNegative() {
+        int result = ToggleNthBit.toggleNthBit(-5, 2);
+        assertEquals(-1, result); // -5 (1111...1011) with 2nd bit toggled becomes -1 (1111...1111)
+    }
+
+    /**
+     * Test the toggleNthBit method with zero.
+     */
+    @Test
+    public void testToggleNthBitZero() {
+        int result = ToggleNthBit.toggleNthBit(0, 2);
+        assertEquals(4, result); // 0 (0000) with 2nd bit toggled becomes 4 (0100)
+    }
+
+    /**
+     * Test the toggleNthBit method with the same bit toggled twice.
+     */
+    @Test
+    public void testToggleNthBitTwice() {
+        int result = ToggleNthBit.toggleNthBit(5, 2);
+        result = ToggleNthBit.toggleNthBit(result, 2);
+        assertEquals(5, result); // Toggling the same bit twice should return the original number
+    }
+}