Added code of Ones Complement

Author: Monk-AbhinayVerma

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

@@ -0,0 +1,39 @@
+package com.thealgorithms.bitmanipulation;
+
+import java.util.Scanner;
+
+public class OnesComplement {
+
+    // Function to get the 1's complement of a binary number
+    public static String onesComplement(String binary) {
+        StringBuilder complement = new StringBuilder();
+        
+        // Invert each bit to get the 1's complement
+        for (int i = 0; i < binary.length(); i++) {
+            if (binary.charAt(i) == '0') {
+                complement.append('1');
+            } else {
+                complement.append('0');
+            }
+        }
+        return complement.toString();
+    }
+
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+
+        // Input a binary number
+        System.out.print("Enter a number: ");
+        int number = scanner.nextInt();
+        
+        String binary = Integer.toBinaryString(number);
+
+        // Compute and print the 1's complement
+        String result = onesComplement(binary);
+        int n = Integer.parseInt(result, 2);
+        System.out.println("1's complement of " + number +"("+binary+")"+" is: " + n + "("+result+")");
+
+        scanner.close();
+    }
+}
+