Change project structure to a Maven Java project + Refactor (#2816)

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

@@ -0,0 +1,37 @@
+package com.thealgorithms.conversions;
+
+import java.util.Scanner;
+
+public class HexaDecimalToDecimal {
+
+    // convert hexadecimal to decimal
+    public static int getHexaToDec(String hex) {
+        String digits = "0123456789ABCDEF";
+        hex = hex.toUpperCase();
+        int val = 0;
+        for (int i = 0; i < hex.length(); i++) {
+            int d = digits.indexOf(hex.charAt(i));
+            val = 16 * val + d;
+        }
+        return val;
+    }
+
+    // Main method gets the hexadecimal input from user and converts it into Decimal output.
+    public static void main(String args[]) {
+        String hexa_Input;
+        int dec_output;
+        Scanner scan = new Scanner(System.in);
+
+        System.out.print("Enter Hexadecimal Number : ");
+        hexa_Input = scan.nextLine();
+
+        // convert hexadecimal to decimal
+        dec_output = getHexaToDec(hexa_Input);
+        /*
+    Pass the string to the getHexaToDec function
+    and it returns the decimal form in the variable dec_output.
+         */
+        System.out.println("Number in Decimal: " + dec_output);
+        scan.close();
+    }
+}