Hexadecimal to Decimal conversion in Java
This tutorial would help in learning the following:
- Conversion of numbers from hexadecimal-system (0 to 9 and A to F) to decimal-system (using 0 to 9)
- Re-conversion of characters into their respective ASCII codes
- Code for Hexadecimal to Decimal conversion in Java
The decimal number system uses all the 10 digits (0 to 9) to represent a number while the hexadecimal uses 15 characters (0 to 9 and A to F, indicating 10 to 15 respectively). The following algorithm is used to convert a hexadecimal-number to a decimal-number:
let the number be 3F
- Give proper index to each digit (or character) of the hexadecimal number, starting with zero and from the rightmost digit (or character)
number->3F
index—->10 - multiply the number (or character with equivalent numerical value) present at index ‘i’ with the ith power of 16
index 0 -> F * 160 = 15 * 160 = 15
index 1 -> 3 * 161 = 48 - add all the products obtained from step 2, to get the equivalent decimal number
15 + 48 = 63
(3F)16 ~ (63)10
Each character used in computing is assigned a special ASCII code (decimal-number-system); hence, once a hexadecimal code is converted to its equivalent decimal-number code, the latter can be assigned a character as per the ASCII convention.
Note, there can be different encoding systems on different machines.
Java Code for Hexadecimal to Decimal conversion
Below is our program:
//This program follows the convention of giving a fullstop after the code for an individual character public class HexaDeconversion { String hexacode; HexaDeconversion()//default constructor { hexacode="43.6F.64.65.20.53.70.65.65.64.79."; } HexaDeconversion(String x)//parameterized constructor { hexacode=x; } public static void main(String args[]) { HexaDeconversion ob; try{//considering the command line argument of the user as the string to be re-converted from hexadecimal format ob=new HexaDeconversion(args[0]); }//going with the default string in case of any exceptions with the command line argument catch(Exception e){ob=new HexaDeconversion();}; System.out.print("The decoded value of hexadecimal code "+ob.hexacode+" is: "); ob.hexaToString(ob.hexacode); } char hexa(char array[]) { int code=0; int temporary; int i; int j=0; for(i=0;array[i]!='\0';i++);//obtaining the index of the last code-character in array[] for(--i;i>=0;i--){ if(Character.isLetter(array[i]))temporary = (int)array[i] - (int)'A' + 10; else temporary = ((int)array[i]) - ((int)('0')); code+=temporary*(int)(Math.pow(16,j++));//Math.pow() helps in giving the required power of 16 } return (char)code;//returning the character corresponding to the integer-code whose value is in 'code' } void hexaToString(String code) { char helper[]=new char[10+1];//assuming that the length of hexadecimal code for one character will not exceed 10 int index = 0; for(int i=0;i<code.length();i++){ if(code.charAt(i)=='.')//printing the value of the code for one character { helper[index]='\0'; System.out.print(hexa(helper)); index=0; } else//stacking up the incomplete code for one character { helper[index++]=code.charAt(i); } } } }//class ends
The output (without command line argument) of our program is given below:
The decoded value of hexadecimal code 43.6F.64.65.20.53.70.65.65.64.79. is: Code Speedy
Summary:
char hexa(char[]):
- the index of the last character in array[] is stored in ‘i’
- the value of ‘j’ corresponds with the required power of 16 that is required for the character at given index ‘i’
- the numerical value of the character-code at index ‘i’ is stored in ‘temporary’
- the sum of products for different indices is stored in ‘code’
- the character corresponding to the value of ‘code’ is returned
void hexaToString(String):
- helper[] stores the hexadecimal code for one character at a time
- hexa(char[]) is called and helper[] is passed to it to print the corresponding character for the hexadecimal code in helper[]
If you want to know how to convert decimal to hexadecimal, then Decimal to Hexadecimal conversion is also here for you. I hope, you enjoyed this article.
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