How to Convert Byte Array to String and Back in Java

How can I convert a byte array to a string in Java and then convert the string back to a byte array?

byte[] byteArray = {-47, 1, 16, 84, 2, 101, 110, 83, 111, 109, 101, 32, 78, 70, 67, 32, 68, 97, 116, 97};

In Java, converting a byte array to a string and back can be achieved using Base64 encoding or by directly manipulating string representations. However, it is crucial to use consistent methods for these conversions – specifically, ensure byte values remain unchanged throughout the process.

import java.util.Base64;

// Convert byte array to Base64 string
byte[] byteArray = {-47, 1, 16, 84, 2, 101, 110, 83, 111, 109, 101, 32, 78, 70, 67, 32, 68, 97, 116, 97};
String encodedString = Base64.getEncoder().encodeToString(byteArray);

// Convert Base64 string back to byte array
byte[] decodedBytes = Base64.getDecoder().decode(encodedString);

Causes

• The issue often arises from how bytes are serialized into strings and then deserialized back into bytes. Simple conversion methods can lead to misinterpretation of data by encoding.
• Using methods like `Arrays.toString()` gives a string format that is not directly convertible back to the original byte values.

Solutions

• Utilize Base64 encoding when converting from byte[] to String and vice versa. This preserves the byte data accurately across the wire and avoids issues with character encoding.
• To convert a byte array to a string: Use `Base64.getEncoder().encodeToString(byteArray)` in Java. To convert it back, use `Base64.getDecoder().decode(encodedString)`.

Mistake: Using `Arrays.toString()` on the byte array, which produces a human-readable string representation that cannot be directly converted back to bytes.

Solution: Instead of `Arrays.toString()`, use Base64 encoding to convert the byte array to a string and back.

Mistake: Neglecting to decode the Base64 string correctly, leading to data corruption.

Solution: Always use the corresponding Base64 decoder on the string to get the original byte array back.