How to Properly Encode and Decode Strings Using Base64 in Java?

Encoding and Decoding Strings in Base64 Using Java

Encoding and decoding strings using Base64 is a common task in many programming scenarios. However, specific implementation details can sometimes lead to issues.

The Problem

The provided code snippet appears to encounter problems with encoding and decoding a string in Base64. The specific issue is not explicitly mentioned.

The Solution

To successfully encode and decode strings using Base64 in Java, the following steps must be carefully followed:

Encoding:

1. Choose an appropriate character encoding for the string. UTF-8 or UTF-16 are common choices.
2. Encode the string into a byte array using the chosen character encoding (e.g., source.getBytes("UTF-8")).
3. Utilize the Base64 class to encode the byte array into a Base64 string (e.g., Base64.encodeToString(byteArray, Base64.DEFAULT)).

Decoding:

1. Receive the Base64-encoded string.
2. Use the Base64 class to decode the Base64 string into a byte array (e.g., Base64.decode(encodedString, Base64.DEFAULT)).
3. Decode the byte array into a string using the character encoding used during encoding (e.g., new String(byteArray, "UTF-8")).

Code Example:

A more complete and improved code example that follows the above steps:

import java.nio.charset.StandardCharsets;
import java.util.Base64;

public class Base64Example {

    public static void main(String[] args) {
        String source = "password";
        byte[] byteArray = source.getBytes(StandardCharsets.UTF_8);

        String encodedString = Base64.getEncoder().encodeToString(byteArray);
        System.out.println("Encoded string: " + encodedString);

        byte[] decodedByteArray = Base64.getDecoder().decode(encodedString);
        String decodedString = new String(decodedByteArray, StandardCharsets.UTF_8);
        System.out.println("Decoded string: " + decodedString);
    }
}

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