Class ByteArrayInputStream

java.lang.Object
java.io.InputStream
java.io.ByteArrayInputStream
All Implemented Interfaces:
Closeable, AutoCloseable
public class ByteArrayInputStream extends InputStream
A ByteArrayInputStream contains an internal buffer that contains bytes that may be read from the stream. An internal counter keeps track of the next byte to be supplied by the read method.

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

Since:
1.0
See Also:

  • 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

    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 java.io.InputStream

    nullInputStream, read, readNBytes, skipNBytes, transferTo

    Methods declared in class java.lang.Object

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

  • 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:

    • 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:

    • 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:

    • 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:

    • 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:

    • 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.