Java Program to Convert Hex String to Byte Array

// Java Program to convert hex
// string to byte array

// Approach 1 - Using parseInt() method of 
// Integer class in Java

import java.io.*;

public class GFG {
   public static void main(String[] args)
   {
     
     // Initializing the hex string and byte array
     String s = "2f4a33";
     byte[] ans = new byte[s.length() / 2];
      
     System.out.println("Hex String : "+s);

     for (int i = 0; i < ans.length; i++) {
         int index = i * 2;
       
           // Using parseInt() method of Integer class
         int val = Integer.parseInt(s.substring(index, index + 2), 16);
         ans[i] = (byte)val;
     }
        
     // Printing the required Byte Array
     System.out.print("Byte Array : ");
     for (int i = 0; i < ans.length; i++) {
         System.out.print(ans[i] + " ");
     }
   }
}

// Java Program to convert hex
// string to byte array

// Approach 1 - Using Byte Array Representation 
// of BigInteger in Java

import java.io.*;
// importing BigInteger class
import java.math.BigInteger;

class GFG {
    public static void main(String[] args)
    {
        String s = "3b4a11";
          
          // converting string to integer value 
        int val = Integer.parseInt(s, 16);
        System.out.println("Hexadecimal String : " + s);
          
          // converting integer value to Byte Array
        BigInteger big = BigInteger.valueOf(val);
        byte[] ans = (big.toByteArray());
      
          // printing the byte array
        System.out.print("Byte Array : ");
        for (int i = 0; i < ans.length; i++)
            System.out.print(ans[i] + " ");
    }
}

// Java program to convert hex
// string to byte array

// Approach 3 - Using Bitwise Shift Operators

import java.io.*;

class GFG {
    public static void main (String[] args) {
          
         // initializing hex string and byte array
        String s ="1f3d44";
         System.out.println("Hex String : " + s);
      
          int len = s.length();
        byte[] ans = new byte[len / 2];
      
        for (int i = 0; i < len; i += 2) {
             // using left shift operator on every character
            ans[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
                    + Character.digit(s.charAt(i+1), 16));
        }
          
          // printing the required result
          System.out.print("Byte Array : ");
          
          for(int i=0;i<ans.length;i++){
             System.out.print(ans[i]+" ");
        }
    }
}