Java Convert Hex String to Byte Array

Tags: HexUtils

In this Java tutorial, we learn how to implement a Java utility method to convert a hex String into byte array in Java programming language.

How to convert hex String to byte array in Java

At this first step, create a new Java class named HexUtils, and a new static method named fromHex(String hex) to convert a hex String into byte array as the following Java code.

HexUtils.java 

public class HexUtils {

    /**
     * this method to convert a hex String to byte array
     * @param hex the input hex String
     * @return the byte array
     */
    public static byte[] fromHex(String hex) {
        byte[] result = new byte[(hex.length() + 1) / 2];
        int stringOffset = 0;
        String hexNumber = null;
        int byteOffset = 0;
        while(stringOffset < hex.length()) {
            hexNumber = hex.substring(stringOffset, stringOffset + 2);
            stringOffset += 2;
            result[byteOffset] = (byte) Integer.parseInt(hexNumber, 16);
            byteOffset++;
        }
        return result;
    }
}

In the following example Java code, we learn how to use the above HexUtils.fromHex(String hex) static method in Java program.

HexUtilsFromHexExample.java 

import java.util.Arrays;

public class HexUtilsFromHexExample {
    public static void main(String... args) {
        String hex = "53696d706c6520536f6c7574696f6e";

        // Convert Hex String to Byte Array
        byte[] data = HexUtils.fromHex(hex);

        System.out.println("Hex String: " + hex);
        System.out.println("Byte array: " + Arrays.toString(data));
        System.out.println("String value from bytes: " + new String(data));
    }
}
The output as below. 
Hex String: 53696d706c6520536f6c7574696f6e
Byte array: [83, 105, 109, 112, 108, 101, 32, 83, 111, 108, 117, 116, 105, 111, 110]
String value from bytes: Simple Solution

Happy Coding 😊

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