Java Encode and Decode Hex String using Apache Commons Codec

Tags: Apache Commons Codec Java Hex Java Encode Hex Java Decode Hex

In this Java tutorial we learn how to use Hex class of Apache Commons Codec library to encode byte[] array to hexadecimal String and decode hexadecimal String to byte[] array.

Table of contents

  1. Add Apache Commons Codec Dependency to Java project
  2. Convert Byte Array to Hex String in Java
  3. Convert Hex String to Byte Array in Java
  4. Convert SHA-1 Hashed Byte Array to Hex String

Add Apache Commons Codec Dependency to Java project

To use Apache Commons Codec library in the Gradle build project, add the following dependency into the build.gradle file. 

implementation group: 'commons-codec', name: 'commons-codec', version: '1.15'

To use the Apache Commons Codec library in the Maven build project, add the following dependency into the pom.xml file. 

<dependency>
    <groupId>commons-codec</groupId>
    <artifactId>commons-codec</artifactId>
    <version>1.15</version>
</dependency>

To have more information about the Apache Commons Codec Java library you can visit the project home page at commons.apache.org/proper/commons-codec/

Convert Byte Array to Hex String in Java

With Apache Commons Codec we can use the Hex.encodeHexString() method to convert an byte[] array into hexadecimal string as following Java program.

HexExample1.java 

import org.apache.commons.codec.binary.Hex;

public class HexExample1 {
    public static void main(String... args) {
        byte[] inputBytes = "SimpleSolution".getBytes();

        String hexString = Hex.encodeHexString(inputBytes);

        System.out.println(hexString);
    }
}
The output as below. 
53696d706c65536f6c7574696f6e

Convert Hex String to Byte Array in Java

We also can decode a hexadecimal String to byte[] array using the Hex.decodeHex() as below.

HexExample2.java 

import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.binary.Hex;

import java.util.Arrays;

public class HexExample2 {
    public static void main(String... args) throws DecoderException {
        String hexString = "53696d706c65536f6c7574696f6e";

        byte[] outputBytes = Hex.decodeHex(hexString);

        System.out.println(Arrays.toString(outputBytes));
        System.out.println(new String(outputBytes));
    }
}
The output as below. 
[83, 105, 109, 112, 108, 101, 83, 111, 108, 117, 116, 105, 111, 110]
SimpleSolution

Convert SHA-1 Hashed Byte Array to Hex String

In the following Java program we show how to use Hex.encodeHexString() to convert SHA-1 hash result from byte[] array to hexadecimal String.

HexExample3.java 

import org.apache.commons.codec.binary.Hex;
import org.apache.commons.codec.digest.DigestUtils;

import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;

public class HexExample3 {
    public static void main(String... args) {
        String inputData = "Simple Solution";

        MessageDigest sha1MessageDigest = DigestUtils.getSha1Digest();
        byte[] hashedBytes = sha1MessageDigest.digest(inputData.getBytes(StandardCharsets.UTF_8));
        String hashedString = Hex.encodeHexString(hashedBytes);

        System.out.println("Input String:" + inputData);
        System.out.println("SHA-1:" + hashedString);
    }
}
The output as below. 
Input String:Simple Solution
SHA-1:23921d0724f0388c797b1383c39a6eaea5c134e6

Happy Coding 😊

Java Apache Commons Codec Tutorial