Fixing java.lang.IllegalArgumentException: Illegal Base64 character 7B

The java.lang.IllegalArgumentException: Illegal Base64 character 7B error occurs when trying to decode a Base64-encoded string containing an illegal character { (ASCII code 123 or hexadecimal 7B). In this post, we will explore the causes of this error and provide solutions to fix it.

What is it?

Base64 is a binary-to-text encoding scheme that converts binary data into a string of ASCII characters. It is commonly used for encoding data in various applications, such as emails, web URLs, and file attachments.

The Base64 encoding scheme uses a set of 64 characters: uppercase letters (A-Z), lowercase letters (a-z), digits (0-9), and two additional characters (+ and / or – and _). The { character is not part of the valid Base64 character set, and its presence in a Base64-encoded string will cause a decoding error.

Causes of the Illegal Base64 character 7B Error

This error may occur due to the following reasons:

• An improperly encoded Base64 string containing illegal characters.
• Attempting to decode a string that is not Base64-encoded.

Here’s an example that triggers the java.lang.IllegalArgumentException: Illegal Base64 character 7B error:

import java.nio.charset.StandardCharsets;import java.util.Base64;public class Base64ErrorExample {public static void main(String[] args) {String input = "SGVsbG8ge3dvcmxkfQ=="; // Contains illegal character '{'byte[] decodedBytes = Base64.getDecoder().decode(input);String decodedString = new String(decodedBytes, StandardCharsets.UTF_8);System.out.println(decodedString);}}

In this example, the input string contains the illegal character { and results in an IllegalArgumentException during decoding.

How to Fix the Illegal Base64 character 7B Error

To fix this error, you should:

1. Ensure that the input string is properly encoded in Base64. You can use an online tool like Base64Encode.org to verify the encoding.
2. Remove or replace any illegal characters in the input string before decoding.
3. Wrap the decoding operation in a try–catch block to handle the IllegalArgumentException and take appropriate action based on your application’s requirements.

Here’s an example of how to handle the error:

import java.nio.charset.StandardCharsets;import java.util.Base64;public class Base64ErrorExample {public static void main(String[] args) {String input = "SGVsbG8ge3dvcmxkfQ=="; // Contains illegal character '{'try {byte[] decodedBytes = Base64.getDecoder().decode(input);String decodedString = new String(decodedBytes, StandardCharsets.UTF_8);System.out.println(decodedString);} catch (IllegalArgumentException e) {System.err.println("Error: Invalid Base64 input string: " + e.getMessage());// Take appropriate action, e.g., log the error or notify the user}}}

In this example, we’ve wrapped the decoding operation in a try–catch block to handle the IllegalArgumentException and display an error message.

Best Practices to Prevent Illegal Base64 character 7B Error

Follow these best practices to avoid encountering the java.lang.IllegalArgumentException: Illegal Base64 character 7B error in your Java projects:

• Ensure that Base64-encoded strings are properly generated and do not contain illegal characters.
• Validate input strings before attempting to decode them in Base64.
• Handle exceptions gracefully by using try–catch blocks and taking appropriate action when errors occur.

Conclusion

In this post, we’ve learned about the java.lang.IllegalArgumentException: Illegal Base64 character 7B error, its causes, and how to fix it. By following best practices and understanding the error’s origin, you can prevent it from occurring in your Java projects and ensure smooth runtime execution.

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