1. Description
2. Field Summary
3. Constructor Summary
4. Method Summary
   1. Methods declared in class InputStream
   2. Methods declared in class Object
5. Field Details
   1. buf
   2. pos
   3. mark
   4. count
6. Constructor Details
   1. ByteArrayInputStream(byte[])
   2. ByteArrayInputStream(byte[], int, int)
7. Method Details
   1. read()
   2. read(byte[], int, int)
   3. readAllBytes()
   4. readNBytes(byte[], int, int)
   5. skip(long)
   6. available()
   7. markSupported()
   8. mark(int)
   9. reset()
   10. close()

• Field Summary

  Fields
  Modifier and Type

  Field

  Description

  protected byte[]

  buf

  An array of bytes that was provided by the creator of the stream.

  protected int

  count

  The index one greater than the last valid byte in the input stream buffer.

  protected int

  mark

  The currently marked position in the stream.

  protected int

  pos

  The index of the next byte to read from the input stream buffer.

• Constructor Summary

  Constructors
  Constructor

  Description

  ByteArrayInputStream(byte[] buf)

  Creates a ByteArrayInputStream so that it uses buf as its buffer array.

  ByteArrayInputStream(byte[] buf, int offset, int length)

  Creates ByteArrayInputStream that uses buf as its buffer array.

• Method Summary

  All MethodsInstance MethodsConcrete Methods

  Modifier and Type

  Method

  Description

  int

  available()

  Returns the number of remaining bytes that can be read (or skipped over) from this input stream.

  void

  close()

  Closing a ByteArrayInputStream has no effect.

  void

  mark(int readAheadLimit)

  Set the current marked position in the stream.

  boolean

  markSupported()

  Tests if this InputStream supports mark/reset.

  int

  read()

  Reads the next byte of data from this input stream.

  int

  read(byte[] b, int off, int len)

  Reads up to len bytes of data into an array of bytes from this input stream.

  byte[]

  readAllBytes()

  Reads all remaining bytes from the input stream.

  int

  readNBytes(byte[] b, int off, int len)

  Reads the requested number of bytes from the input stream into the given byte array.

  void

  reset()

  Resets the buffer to the marked position.

  long

  skip(long n)

  Skips n bytes of input from this input stream.

  Methods declared in class InputStream

  nullInputStream, read, readNBytes, skipNBytes, transferTo

  Modifier and Type

  Method

  Description

  static InputStream

  nullInputStream()

  Returns a new InputStream that reads no bytes.

  int

  read(byte[] b)

  Reads some number of bytes from the input stream and stores them into the buffer array b.

  byte[]

  readNBytes(int len)

  Reads up to a specified number of bytes from the input stream.

  void

  skipNBytes(long n)

  Skips over and discards exactly n bytes of data from this input stream.

  long

  transferTo(OutputStream out)

  Reads all bytes from this input stream and writes the bytes to the given output stream in the order that they are read.

  Methods declared in class Object

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

  Modifier and Type

  Method

  Description

  protected Object

  clone()

  Creates and returns a copy of this object.

  boolean

  equals(Object obj)

  Indicates whether some other object is "equal to" this one.

  protected void

  finalize()

  Deprecated, for removal: This API element is subject to removal in a future version.

  Finalization is deprecated and subject to removal in a future release.

  final Class<?>

  getClass()

  Returns the runtime class of this Object.

  int

  hashCode()

  Returns a hash code value for this object.

  final void

  notify()

  Wakes up a single thread that is waiting on this object's monitor.

  final void

  notifyAll()

  Wakes up all threads that are waiting on this object's monitor.

  String

  toString()

  Returns a string representation of the object.

  final void

  wait()

  Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

  final void

  wait(long timeoutMillis)

  Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

  final void

  wait(long timeoutMillis, int nanos)

  Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

• Field Details

  • buf

    protected byte[] buf

    An array of bytes that was provided by the creator of the stream. Elements buf[0] through buf[count-1] are the only bytes that can ever be read from the stream; element buf[pos] is the next byte to be read.

  • pos

    protected int pos

    The index of the next byte to read from the input stream buffer. This value should always be nonnegative and not larger than the value of count. The next byte to be read from the input stream buffer will be buf[pos].

  • mark

    protected int mark

    The currently marked position in the stream. ByteArrayInputStream objects are marked at position zero by default when constructed. They may be marked at another position within the buffer by the mark() method. The current buffer position is set to this point by the reset() method.

    If no mark has been set, then the value of mark is the offset passed to the constructor (or 0 if the offset was not supplied).

    Since: 1.1

  • count

    protected int count

    The index one greater than the last valid byte in the input stream buffer. This value should always be nonnegative and not larger than the length of buf. It is one greater than the position of the last byte within buf that can ever be read from the input stream buffer.

• Constructor Details

  • ByteArrayInputStream

    public ByteArrayInputStream(byte[] buf)

    Creates a ByteArrayInputStream so that it uses buf as its buffer array. The buffer array is not copied. The initial value of pos is 0 and the initial value of count is the length of buf.

    Parameters: buf - the input buffer.

  • ByteArrayInputStream

    public ByteArrayInputStream(byte[] buf, int offset, int length)

    Creates ByteArrayInputStream that uses buf as its buffer array. The initial value of pos is offset and the initial value of count is the minimum of offset+length and buf.length. The buffer array is not copied. The buffer's mark is set to the specified offset.

    Parameters: buf - the input buffer. offset - the offset in the buffer of the first byte to read. length - the maximum number of bytes to read from the buffer.

• Method Details

  • read

    public int read()

    Reads the next byte of data from this input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned.

    This read method cannot block.

    Specified by: read in class InputStream Returns: the next byte of data, or -1 if the end of the stream is reached.

  • read

    public int read(byte[] b, int off, int len)

    Reads up to len bytes of data into an array of bytes from this input stream. If pos equals count, then -1 is returned to indicate end of file. Otherwise, the number k of bytes read is equal to the smaller of len and count-pos. If k is positive, then bytes buf[pos] through buf[pos+k-1] are copied into b[off] through b[off+k-1] in the manner performed by System.arraycopy. The value k is added into pos and k is returned.

    Unlike the overridden method of InputStream, this method returns -1 instead of zero if the end of the stream has been reached and len == 0.

    This read method cannot block.

    Overrides: read in class InputStream Parameters: b - the buffer into which the data is read. off - the start offset in array b at which the data is written. len - the maximum number of bytes to read. Returns: the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached. Throws: NullPointerException - If b is null. IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off See Also:

    • InputStream.read()

  • readAllBytes

    public byte[] readAllBytes()

    Description copied from class: InputStream

    Reads all remaining bytes from the input stream. This method blocks until all remaining bytes have been read and end of stream is detected, or an exception is thrown. This method does not close the input stream.

    When this stream reaches end of stream, further invocations of this method will return an empty byte array.

    Note that this method is intended for simple cases where it is convenient to read all bytes into a byte array. It is not intended for reading input streams with large amounts of data.

    The behavior for the case where the input stream is asynchronously closed, or the thread interrupted during the read, is highly input stream specific, and therefore not specified.

    If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes have been read. Consequently the input stream may not be at end of stream and may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.

    Overrides: readAllBytes in class InputStream Returns: a byte array containing the bytes read from this input stream

  • readNBytes

    public int readNBytes(byte[] b, int off, int len)

    Description copied from class: InputStream

    Reads the requested number of bytes from the input stream into the given byte array. This method blocks until len bytes of input data have been read, end of stream is detected, or an exception is thrown. The number of bytes actually read, possibly zero, is returned. This method does not close the input stream.

    In the case where end of stream is reached before len bytes have been read, then the actual number of bytes read will be returned. When this stream reaches end of stream, further invocations of this method will return zero.

    If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read up to len bytes.

    The first byte read is stored into element b[off], the next one in to b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k ] through b[off+len-1] unaffected.

    The behavior for the case where the input stream is asynchronously closed, or the thread interrupted during the read, is highly input stream specific, and therefore not specified.

    If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes of b have been updated with data from the input stream. Consequently the input stream and b may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.

    Overrides: readNBytes in class InputStream Parameters: b - the byte array into which the data is read off - the start offset in b at which the data is written len - the maximum number of bytes to read Returns: the actual number of bytes read into the buffer

  • skip

    public long skip(long n)

    Skips n bytes of input from this input stream. Fewer bytes might be skipped if the end of the input stream is reached. The actual number k of bytes to be skipped is equal to the smaller of n and count-pos. The value k is added into pos and k is returned.

    Overrides: skip in class InputStream Parameters: n - the number of bytes to be skipped. Returns: the actual number of bytes skipped. See Also:

    • InputStream.skipNBytes(long)

  • available

    public int available()

    Returns the number of remaining bytes that can be read (or skipped over) from this input stream.

    The value returned is count - pos, which is the number of bytes remaining to be read from the input buffer.

    Overrides: available in class InputStream Returns: the number of remaining bytes that can be read (or skipped over) from this input stream without blocking.

  • markSupported

    public boolean markSupported()

    Tests if this InputStream supports mark/reset.

    Overrides: markSupported in class InputStream Implementation Requirements: The markSupported method of ByteArrayInputStream always returns true. Returns: true Since: 1.1 See Also:

    • InputStream.mark(int)
    • InputStream.reset()

  • mark

    public void mark(int readAheadLimit)

    Set the current marked position in the stream. ByteArrayInputStream objects are marked at position zero by default when constructed. They may be marked at another position within the buffer by this method.

    If no mark has been set, then the value of the mark is the offset passed to the constructor (or 0 if the offset was not supplied).

    Note: The readAheadLimit for this class has no meaning.

    Overrides: mark in class InputStream Parameters: readAheadLimit - the maximum limit of bytes that can be read before the mark position becomes invalid. Since: 1.1 See Also:

    • InputStream.reset()

  • reset

    public void reset()

    Resets the buffer to the marked position. The marked position is 0 unless another position was marked or an offset was specified in the constructor.

    Overrides: reset in class InputStream See Also:

    • InputStream.mark(int)
    • IOException

  • close

    public void close() throws IOException

    Closing a ByteArrayInputStream has no effect. The methods in this class can be called after the stream has been closed without generating an IOException.

    Specified by: close in interface AutoCloseable Specified by: close in interface Closeable Overrides: close in class InputStream Throws: IOException - if an I/O error occurs.

Report a bug or suggest an enhancement
For further API reference and developer documentation see the Java SE Documentation, which contains more detailed, developer-targeted descriptions with conceptual overviews, definitions of terms, workarounds, and working code examples. Other versions.
Java is a trademark or registered trademark of Oracle and/or its affiliates in the US and other countries.
Copyright © 1993, 2026, Oracle and/or its affiliates, 500 Oracle Parkway, Redwood Shores, CA 94065 USA.
All rights reserved. Use is subject to license terms and the documentation redistribution policy.