How do I decode Base64 data in Java?

To decode Base64 data in Java, you can use the Base64 class provided in the java.util package starting from Java 8. Here’s a step-by-step explanation:

Steps to Decode Base64 Data:

1. Import the Required Class:
   • Use java.util.Base64 to access the Base64 decoding functionality.
2. Get the Decoder:
   • Use Base64.getDecoder() to obtain a Base64.Decoder instance.
3. Decode the Data:
   • Call the decode() method on the Base64.Decoder instance with the Base64 string as input.
   • The output will be a byte array.
4. Convert Byte Array to String (if needed):
   • If the original data was a string, convert the byte array back to a string using new String(byteArray).

Example Process:

1. Input Base64 String: A string encoded in Base64 format.
2. Decoding: Decode it into the original byte array.
3. Output: Interpret the byte array as needed (e.g., convert it back to a string for text data).

Key Notes:

• The Base64 class in java.util supports encoding and decoding.
• If you’re working with older versions of Java (before Java 8), use external libraries like Apache Commons Codec or Sun’s sun.misc.BASE64Decoder (deprecated).
• Always ensure the input data is valid Base64 to avoid decoding errors.