How to convert Hexadecimal number to Decimal number in Java?

Problem Description :

Write a program in Java that converts Hexadecimal number to Decimal number.

Java program that converts hexadecimal number to decimal number.

Hexadecimal to Decimal conversion

Concept :

Click here to learn how to convert hexadecimal number to decimal number Mathematically.

Java Program :

package com.javamultiplex.baseconversion; import java.util.Scanner; /** * * @author Rohit Agarwal * @category Base Conversion * @problem Convert Hexadecimal to Decimal * */ public class HexadecimalToDecimal { public static void main(String[] args) { Scanner input = null; try { input = new Scanner(System.in); System.out.println("Enter hexadecimal number : "); String number = input.next(); if (isHexadecimalNumber(number)) { int decimal = getDecimalNumber(number); System.out.println("Decimal Number : " + decimal); } else { System.out.println("Please enter valid hexadecimal number."); } } finally { if (input != null) { input.close(); } } } private static int getDecimalNumber(String number) { // Converting String to StringBuilder. StringBuilder string = new StringBuilder(number); string = string.reverse(); int length = string.length(); int digit, power, sum = 0; for (int i = 0; i < length; i++) { if (Character.isDigit(string.charAt(i))) { digit = string.charAt(i) - 48; } else { digit = getHexadecimalCharacterDigit(string.charAt(i)); } power = (int) Math.pow(16, i); sum = sum + digit * power; } return sum; } private static int getHexadecimalCharacterDigit(char ch) { int digit = 0; switch (ch) { case 'A': case 'a': digit = 10; break; case 'B': case 'b': digit = 11; break; case 'C': case 'c': digit = 12; break; case 'D': case 'd': digit = 13; break; case 'E': case 'e': digit = 14; break; case 'F': case 'f': digit = 15; break; } return digit; } private static boolean isHexadecimalNumber(String number) { /* * Regular expression that matches string containing only digits [0-9] * and alphabets [A-F] or [a-f] */ String pattern = "^[0-9a-fA-F]+$"; boolean result = false; if (number.matches(pattern)) { result = true; } return result; } }

Output :

Output - How to convert Hexadecimal number to Decimal number in Java?

References :

https://en.wikipedia.org/wiki/Regular_expression

http://docs.oracle.com/javase/7/docs/api/java/lang/String.html

https://docs.oracle.com/javase/7/docs/api/java/lang/StringBuilder.html

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Tags : Conversion problems, Hexadecimal to Decimal, Solution in Java, String, StringBuilder, Regular expressions, switch statement, if else statement, for loop, while loop.

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How to convert Hexadecimal number to Decimal number in Java?

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