Added binary string to decimal converter (#6915)

added binary string to decimal converter

src/main/java/com/thealgorithms/conversions/BinaryToDecimal.java

@@ -30,4 +30,30 @@ final class BinaryToDecimal {
         }
         return decimalValue;
     }
+
+    /**
+     * Converts a binary String to its decimal equivalent using bitwise operators.
+     *
+     * @param binary The binary number to convert.
+     * @return The decimal equivalent of the binary number.
+     * @throws IllegalArgumentException If the binary number contains digits other than 0 and 1.
+     */
+    public static long binaryStringToDecimal(String binary) {
+        boolean isNegative = binary.charAt(0) == '-';
+        if (isNegative) {
+            binary = binary.substring(1);
+        }
+
+        long decimalValue = 0;
+
+        for (char bit : binary.toCharArray()) {
+            if (bit != '0' && bit != '1') {
+                throw new IllegalArgumentException("Incorrect binary digit: " + bit);
+            }
+            // shift left by 1 (multiply by 2) and add bit value
+            decimalValue = (decimalValue << 1) | (bit - '0');
+        }
+
+        return isNegative ? -decimalValue : decimalValue;
+    }
 }