How to Convert Hex to String in Java

1. Convert Hex to String in Java Using Integer.parseInt and Character.toChars
2. Convert Hex to String in Java Using BigInteger Class
3. Convert Hex to String in Java Using Apache Commons Codec
4. Conclusion

Hexadecimal representation is a common format for expressing binary data, and converting hexadecimal strings to regular text strings is a frequent task in Java programming.

In this article, we’ll explore different approaches to achieve this conversion, providing insights into the underlying concepts and considerations.

Convert Hex to String in Java Using Integer.parseInt and Character.toChars

One approach to convert a hexadecimal string to a human-readable string involves using the Integer.parseInt method to convert the hex string to an integer and then utilizing the Character.toChars method to transform the integer into a corresponding Unicode character.

Let’s break down the process of converting a hex string to a string using Integer.parseInt and Character.toChars in Java:

String hexString =
    "48656c6c6f2120546869732069732064656c6674737461636b2e636f6d"; // Example hex string

String[] hexPairs = hexString.split("(?<=\\G.{2})");

StringBuilder resultBuilder = new StringBuilder();
for (String hexPair : hexPairs) {
  int decimalValue = Integer.parseInt(hexPair, 16);
  resultBuilder.append(Character.toChars(decimalValue));
}

String resultString = resultBuilder.toString();

Here’s the complete Java code for the conversion process:

public class HexToStringConverter {
  public static void main(String[] args) {
    String hexString = "48656c6c6f2120546869732069732064656c6674737461636b2e636f6d";

    String[] hexPairs = hexString.split("(?<=\\G.{2})");

    StringBuilder resultBuilder = new StringBuilder();
    for (String hexPair : hexPairs) {
      int decimalValue = Integer.parseInt(hexPair, 16);
      resultBuilder.append(Character.toChars(decimalValue));
    }

    String resultString = resultBuilder.toString();

    System.out.println("Before the conversion: " + hexString);
    System.out.println("After the conversion: " + resultString);
  }
}

Output:

Before the conversion: 48656c6c6f2120546869732069732064656c6674737461636b2e636f6d
After the conversion: Hello! This is delftstack.com

As you can see, converting a hex string to a string in Java using Integer.parseInt and Character.toChars involves breaking the hex string into pairs, converting each pair to integers, and then converting each integer to its corresponding Unicode character. This approach allows for an accurate conversion of hex values to human-readable strings.

Note that you need to handle exceptions appropriately, such as NumberFormatException when parsing the hex string, to create a robust solution for your application.

Convert Hex to String in Java Using BigInteger Class

Converting a hexadecimal string to a human-readable string in Java can be achieved using the versatile BigInteger class. This approach is particularly useful when dealing with large hexadecimal values.

Let’s explore the step-by-step process of converting a hex string to a string using the BigInteger class in Java:

String hexString =
    "48656c6c6f2120546869732069732064656c6674737461636b2e636f6d"; // Example hex string

BigInteger bigInteger = new BigInteger(hexString, 16);

String resultString = new String(bigInteger.toByteArray());

Here’s the complete Java code for the conversion process:

import java.math.BigInteger;

public class HexToStringConverter {
  public static void main(String[] args) {
    String hexString = "48656c6c6f2120546869732069732064656c6674737461636b2e636f6d";

    BigInteger bigInteger = new BigInteger(hexString, 16);

    String resultString = new String(bigInteger.toByteArray());

    System.out.println("Before the conversion: " + hexString);
    System.out.println("After the conversion: " + resultString);
  }
}

Output:

Before the conversion: 48656c6c6f2120546869732069732064656c6674737461636b2e636f6d
After the conversion: Hello! This is delftstack.com

By following this method, you can effortlessly convert hex values to human-readable strings, especially when working with substantial hexadecimal inputs.

Convert Hex to String in Java Using Apache Commons Codec

Converting a hexadecimal string to a human-readable string in Java can be efficiently achieved using the Apache Commons Codec library.

Apache Commons Codec is a library that provides implementations of common encoders and decoders. The library is part of the Apache Commons project and aims to provide robust, efficient, and reusable code for encoding and decoding various data formats.

Before using Apache Commons Codec for hex-to-string conversion, you need to include the library in your project. You can download the library from the Apache Commons website (https://commons.apache.org/proper/commons-codec/) or use a build tool like Maven or Gradle to manage dependencies.

If you are using Maven, add the following dependency to your pom.xml:

<dependency>
    <groupId>commons-codec</groupId>
    <artifactId>commons-codec</artifactId>
    <version>1.15</version> <!-- Use the latest version available -->
</dependency>

For Gradle, include the following in your build.gradle file:

implementation 'commons-codec:commons-codec:1.15' // Use the latest version available

Now, let’s explore how to use Apache Commons Codec to convert hexadecimal strings to regular strings in Java.

String hexString =
    "48656c6c6f2120546869732069732064656c6674737461636b2e636f6d"; // Example hex string

byte[] byteArray = org.apache.commons.codec.binary.Hex.decodeHex(hexString.toCharArray());

String resultString = new String(byteArray);

Here’s the complete Java code for the conversion process:

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

public class HexToStringConverter {
  public static void main(String[] args) {
    String hexString = "48656c6c6f2120546869732069732064656c6674737461636b2e636f6d";

    try {
      byte[] byteArray = Hex.decodeHex(hexString.toCharArray());

      String resultString = new String(byteArray);

      System.out.println("Before the conversion: " + hexString);
      System.out.println("After the conversion: " + resultString);
    } catch (DecoderException e) {
      System.err.println("Error decoding hex string: " + e.getMessage());
    }
  }
}

Output:

Before the conversion: 48656c6c6f2120546869732069732064656c6674737461636b2e636f6d
After the conversion: Hello! This is delftstack.com

In this code, we added a try-catch block around the Hex.decodeHex method to catch the potential DecoderException. If an exception occurs during the decoding process, it will print an error message.

You can customize the exception-handling logic based on your application’s requirements. When using the Apache Commons Codec library, it is important to be sure that you include the Apache Commons Codec library in your project.

Conclusion

Converting hexadecimal strings to regular strings in Java involves choosing an appropriate method based on your specific requirements and the Java version you are using. Whether you opt for built-in functions or external libraries like Apache Commons Codec, understanding the underlying concepts and considerations will help you make informed decisions for your coding tasks.