Created
September 20, 2017 12:10
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Hexadecimal to Decimal Converter
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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; | |
} | |
} |
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