Java Byte Array to String to Byte Array

java

encoding-decoding

base64-conversions

data-integrity

byAnton Shumikhin·Dec 29, 2024

Convert a byte array to a String and back using UTF-8 encoding for consistency, with new String(byteArray, StandardCharsets.UTF_8) and string.getBytes(StandardCharsets.UTF_8):

byte[] bytes = { 72, 101, 108, 108, 111 };
// Because "Hello" is better than unreadable signs
String str = new String(bytes, StandardCharsets.UTF_8); 
byte[] backToBytes = str.getBytes(StandardCharsets.UTF_8);

Note: Always use the same charset when converting to avoid the "character chaos".

Essential: Encoding & Decoding

Any string conversion process involves encoding and decoding. UTF-8 is a safe bet to cover a comprehensive character set and to ensure data integrity. Whenever dealing with byte arrays and strings, remember—encoding matters!

Handling arrays: Tools & Tips

Consider using classes such as ArrayUtils from Apache Commons Codec, designed specifically to ease Base64 conversions and assure compatibility.

Base64: Safe & Reliable

For conversion that retains binary data and non-text bytes, use Base64:

// Encoding byte array into Base64 string
// Because we love encrypted letters
String base64Encoded = Base64.getEncoder().encodeToString(bytes);

// Decoding Base64 string back to byte array
// Back to reality
byte[] base64Decoded = Base64.getDecoder().decode(base64Encoded);

This ensures safety, compatibility and is tamper-proof between Java and other languages like Python.

Polishing conversion: Trimming & Parsing

How to handle strings like [1, 2, 3]? Trim and parse!:

String byteValuesStr = "[1, 2, 3]";
// Getting rid of annoying brackets
byteValuesStr = byteValuesStr.substring(1, byteValuesStr.length() - 1);
String[] byteValues = byteValuesStr.split(",\\s*");
// We like our bytes in a line, not strung out
byte[] parsedBytes = new byte[byteValues.length];

for (int i = 0; i < byteValues.length; i++) {
    // We like our bytes to be bytes, not strings
    parsedBytes[i] = Byte.parseByte(byteValues[i]);
}

Note: Do remember to handle any extra characters like brackets that might creep in.

Data Integrity: Checksums & Hashes

Checksums or hash functions during data transfer can help maintain the integrity and verify the authenticity of the data in transit.

Peeking into server's representation

Always match the server-side string creation that varies with the language and the library being used. Learn to mirror conditions when parsing in Java.

Beyond ToString: Reconstructing Byte Array

While Arrays.toString() is human-friendly, it's not intended for byte array reconstruction due to the extra characters involved. Use this method wisely to avoid inconsistencies and errors.

Testing: Success lies in Simulation

Simulating the end-to-end process and the workflow of sending and receiving data can ensure the reliability of your code. Balance your trade-off!

Real-world applications

In adverse real-world scenarios like transferring images or network protocols, handle conversions with the right encoding. Also, consider making the base64 string URL-safe.

explain-codes / Java / Java Byte Array to String to Byte Array

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