Base64 (Java Platform SE 8 )
Keywords: java.util.Base64 class
Date: 2026-04-22

compact1, compact2, compact3
java.util

## Class Base64

- java.lang.Object
- - java.util.Base64

-     public class Base64
      extends Object

  This class consists exclusively of static methods for obtaining encoders and decoders for the Base64 encoding scheme. The implementation of this class supports the following types of Base64 as specified in RFC 4648 and RFC 2045.
  - Basic

    Uses "The Base64 Alphabet" as specified in Table 1 of RFC 4648 and RFC 2045 for encoding and decoding operation. The encoder does not add any line feed (line separator) character. The decoder rejects data that contains characters outside the base64 alphabet.

  - URL and Filename safe

    Uses the "URL and Filename safe Base64 Alphabet" as specified in Table 2 of RFC 4648 for encoding and decoding. The encoder does not add any line feed (line separator) character. The decoder rejects data that contains characters outside the base64 alphabet.

  - MIME

    Uses the "The Base64 Alphabet" as specified in Table 1 of RFC 2045 for encoding and decoding operation. The encoded output must be represented in lines of no more than 76 characters each and uses a carriage return `'\r'` followed immediately by a linefeed `'\n'` as the line separator. No line separator is added to the end of the encoded output. All line separators or other characters not found in the base64 alphabet table are ignored in decoding operation.

  Unless otherwise noted, passing a `null` argument to a method of this class will cause a `NullPointerException` to be thrown.

  Since:
    1.8

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `static class` | `Base64.Decoder` This class implements a decoder for decoding byte data using the Base64 encoding scheme as specified in RFC 4648 and RFC 2045.
    `static class` | `Base64.Encoder` This class implements an encoder for encoding byte data using the Base64 encoding scheme as specified in RFC 4648 and RFC 2045.

  - ### Method Summary

    All Methods Static Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static Base64.Decoder` | `getDecoder()` Returns a `Base64.Decoder` that decodes using the Basic type base64 encoding scheme.
    `static Base64.Encoder` | `getEncoder()` Returns a `Base64.Encoder` that encodes using the Basic type base64 encoding scheme.
    `static Base64.Decoder` | `getMimeDecoder()` Returns a `Base64.Decoder` that decodes using the MIME type base64 decoding scheme.
    `static Base64.Encoder` | `getMimeEncoder()` Returns a `Base64.Encoder` that encodes using the MIME type base64 encoding scheme.
    `static Base64.Encoder` | `getMimeEncoder(int lineLength, byte[] lineSeparator)` Returns a `Base64.Encoder` that encodes using the MIME type base64 encoding scheme with specified line length and line separators.
    `static Base64.Decoder` | `getUrlDecoder()` Returns a `Base64.Decoder` that decodes using the URL and Filename safe type base64 encoding scheme.
    `static Base64.Encoder` | `getUrlEncoder()` Returns a `Base64.Encoder` that encodes using the URL and Filename safe type base64 encoding scheme.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Method Detail

    - #### getEncoder

          public static Base64.Encoder getEncoder()

      Returns a `Base64.Encoder` that encodes using the Basic type base64 encoding scheme.
      Returns:
        A Base64 encoder.

    - #### getUrlEncoder

          public static Base64.Encoder getUrlEncoder()

      Returns a `Base64.Encoder` that encodes using the URL and Filename safe type base64 encoding scheme.
      Returns:
        A Base64 encoder.

    - #### getMimeEncoder

          public static Base64.Encoder getMimeEncoder()

      Returns a `Base64.Encoder` that encodes using the MIME type base64 encoding scheme.
      Returns:
        A Base64 encoder.

    - #### getMimeEncoder

          public static Base64.Encoder getMimeEncoder(int lineLength,
                                                      byte[] lineSeparator)

      Returns a `Base64.Encoder` that encodes using the MIME type base64 encoding scheme with specified line length and line separators.
      Parameters:
        `lineLength` - the length of each output line (rounded down to nearest multiple of 4). If `lineLength <= 0` the output will not be separated in lines
        `lineSeparator` - the line separator for each output line
      Returns:
        A Base64 encoder.
      Throws:
        `IllegalArgumentException` - if `lineSeparator` includes any character of "The Base64 Alphabet" as specified in Table 1 of RFC 2045.

    - #### getDecoder

          public static Base64.Decoder getDecoder()

      Returns a `Base64.Decoder` that decodes using the Basic type base64 encoding scheme.
      Returns:
        A Base64 decoder.

    - #### getUrlDecoder

          public static Base64.Decoder getUrlDecoder()

      Returns a `Base64.Decoder` that decodes using the URL and Filename safe type base64 encoding scheme.
      Returns:
        A Base64 decoder.

    - #### getMimeDecoder

          public static Base64.Decoder getMimeDecoder()

      Returns a `Base64.Decoder` that decodes using the MIME type base64 decoding scheme.
      Returns:
        A Base64 decoder.

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