Constructor Summary

Method Summary

Constructor Details

• InputStream

  public InputStream()

  Constructor for subclasses to call.

Method Details

• nullInputStream

  public static InputStream nullInputStream()

  Returns a newInputStream that reads no bytes. The returned stream is initially open. The stream is closed by calling theclose() method. Subsequent calls toclose() have no effect.

  While the stream is open, theavailable(),read(),read(byte[]),read(byte[], int, int),readAllBytes(),readNBytes(byte[], int, int),readNBytes(int),skip(long),skipNBytes(long), andtransferTo() methods all behave as if end of stream has been reached. After the stream has been closed, these methods all throwIOException.

  ThemarkSupported() method returnsfalse. Themark() method does nothing, and thereset() method throwsIOException.

  Returns:

  anInputStream which contains no bytes

  Since:

  11

• read

  public abstract int read() throwsIOException

  Reads the next byte of data from the input stream. The value byte is returned as anint in the range0 to255. If no byte is available because the end of the stream has been reached, the value-1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

  Returns:

  the next byte of data, or-1 if the end of the stream is reached.

  Throws:

  IOException - if an I/O error occurs.

• read

  public int read(byte[] b) throwsIOException

  Reads some number of bytes from the input stream and stores them into the buffer arrayb. The number of bytes actually read is returned as an integer. This method blocks until input data is available, end of file is detected, or an exception is thrown.

  If the length ofb is zero, then no bytes are read and0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at the end of the file, the value-1 is returned; otherwise, at least one byte is read and stored intob.

  The first byte read is stored into elementb[0], the next one intob[1], and so on. The number of bytes read is, at most, equal to the length ofb. Letk be the number of bytes actually read; these bytes will be stored in elementsb[0] throughb[k-1], leaving elementsb[k] throughb[b.length-1] unaffected.

  Implementation Requirements:

  Theread(b) method for classInputStream has the same effect as:

  Copy

      read(b, 0, b.length)

  Parameters:

  b - the buffer into which the data is 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:

  IOException - If the first byte cannot be read for any reason other than the end of the file, if the input stream has been closed, or if some other I/O error occurs.

  NullPointerException - ifb isnull.

  See Also:

  • read(byte[], int, int)

• read

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

  Reads up tolen bytes of data from the input stream into an array of bytes. An attempt is made to read as many aslen bytes, but a smaller number may be read. The number of bytes actually read is returned as an integer.

  This method blocks until input data is available, end of file is detected, or an exception is thrown.

  Iflen is zero, then no bytes are read and0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value-1 is returned; otherwise, at least one byte is read and stored intob.

  The first byte read is stored into elementb[off], the next one intob[off+1], and so on. The number of bytes read is, at most, equal tolen. Letk be the number of bytes actually read; these bytes will be stored in elementsb[off] throughb[off+k-1], leaving elementsb[off+k] throughb[off+len-1] unaffected.

  In every case, elementsb[0] throughb[off-1] and elementsb[off+len] throughb[b.length-1] are unaffected.

  Implementation Requirements:

  Theread(b, off, len) method for classInputStream simply calls the methodread() repeatedly. If the first such call results in anIOException, that exception is returned from the call to theread(b,off,len) method. If any subsequent call toread() results in aIOException, the exception is caught and treated as if it were end of file; the bytes read up to that point are stored intob and the number of bytes read before the exception occurred is returned. The default implementation of this method blocks until the requested amount of input datalen has been read, end of file is detected, or an exception is thrown. Subclasses are encouraged to provide a more efficient implementation of this method.

  Parameters:

  b - the buffer into which the data is read.

  off - the start offset in arrayb 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:

  IOException - If the first byte cannot be read for any reason other than end of file, or if the input stream has been closed, or if some other I/O error occurs.

  NullPointerException - Ifb isnull.

  IndexOutOfBoundsException - Ifoff is negative,len is negative, orlen is greater thanb.length - off

  See Also:

  • read()

• readAllBytes

  public byte[] readAllBytes() throwsIOException

  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 isasynchronously 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.

  Implementation Requirements:

  This method invokesreadNBytes(int) with a length ofInteger.MAX_VALUE.

  Returns:

  a byte array containing the bytes read from this input stream

  Throws:

  IOException - if an I/O error occurs

  OutOfMemoryError - if an array of the required size cannot be allocated.

  Since:

  9

• readNBytes

  public byte[] readNBytes(int len) throwsIOException

  Reads up to a specified number of bytes from the input stream. This method blocks until the requested number of bytes has been read, end of stream is detected, or an exception is thrown. This method does not close the input stream.

  The length of the returned array equals the number of bytes read from the stream. Iflen is zero, then no bytes are read and an empty byte array is returned. Otherwise, up tolen bytes are read from the stream. Fewer thanlen bytes may be read if end of stream is encountered.

  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 the specified number of bytes into a byte array. The total amount of memory allocated by this method is proportional to the number of bytes read from the stream which is bounded bylen. Therefore, the method may be safely called with very large values oflen provided sufficient memory is available.

  The behavior for the case where the input stream isasynchronously 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.

  Implementation Note:

  The number of bytes allocated to read data from this stream and return the result is bounded by2*(long)len, inclusive.

  Parameters:

  len - the maximum number of bytes to read

  Returns:

  a byte array containing the bytes read from this input stream

  Throws:

  IllegalArgumentException - iflength is negative

  IOException - if an I/O error occurs

  OutOfMemoryError - if an array of the required size cannot be allocated.

  Since:

  11

• readNBytes

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

  Reads the requested number of bytes from the input stream into the given byte array. This method blocks untillen 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 beforelen 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.

  Iflen is zero, then no bytes are read and0 is returned; otherwise, there is an attempt to read up tolen bytes.

  The first byte read is stored into elementb[off], the next one in tob[off+1], and so on. The number of bytes read is, at most, equal tolen. Letk be the number of bytes actually read; these bytes will be stored in elementsb[off] throughb[off+k-1], leaving elementsb[off+k] throughb[off+len-1] unaffected.

  The behavior for the case where the input stream isasynchronously 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 ofb have been updated with data from the input stream. Consequently the input stream andb may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.

  Parameters:

  b - the byte array into which the data is read

  off - the start offset inb at which the data is written

  len - the maximum number of bytes to read

  Returns:

  the actual number of bytes read into the buffer

  Throws:

  IOException - if an I/O error occurs

  NullPointerException - ifb isnull

  IndexOutOfBoundsException - Ifoff is negative,len is negative, orlen is greater thanb.length - off

  Since:

  9

• skip

  public long skip(long n) throwsIOException

  Skips over and discardsn bytes of data from this input stream. Theskip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly0. This may result from any of a number of conditions; reaching end of file beforen bytes have been skipped is only one possibility. The actual number of bytes skipped is returned. Ifn is negative, theskip method for classInputStream always returns 0, and no bytes are skipped. Subclasses may handle the negative value differently.

  Implementation Requirements:

  Theskip method implementation of this class creates a byte array and then repeatedly reads into it untiln bytes have been read or the end of the stream has been reached. Subclasses are encouraged to provide a more efficient implementation of this method. For instance, the implementation may depend on the ability to seek.

  Parameters:

  n - the number of bytes to be skipped.

  Returns:

  the actual number of bytes skipped which might be zero.

  Throws:

  IOException - if an I/O error occurs.

  See Also:

  • skipNBytes(long)

• skipNBytes

  public void skipNBytes(long n) throwsIOException

  Skips over and discards exactlyn bytes of data from this input stream. Ifn is zero, then no bytes are skipped. Ifn is negative, then no bytes are skipped. Subclasses may handle the negative value differently.

  This method blocks until the requested number of bytes has been skipped, end of file is reached, or an exception is thrown.

  If end of stream is reached before the stream is at the desired position, then anEOFException is thrown.

  If an I/O error occurs, then the input stream may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.

  Implementation Requirements:

  Ifn is zero or negative, then no bytes are skipped. Ifn is positive, the default implementation of this method invokesskip() repeatedly with its parameter equal to the remaining number of bytes to skip until the requested number of bytes has been skipped or an error condition occurs. If at any point the return value ofskip() is negative or greater than the remaining number of bytes to be skipped, then anIOException is thrown. Ifskip() ever returns zero, thenread() is invoked to read a single byte, and if it returns-1, then anEOFException is thrown. Any exception thrown byskip() orread() will be propagated.

  Implementation Note:

  Subclasses are encouraged to provide a more efficient implementation of this method.

  Parameters:

  n - the number of bytes to be skipped.

  Throws:

  EOFException - if end of stream is encountered before the stream can be positionedn bytes beyond its position when this method was invoked.

  IOException - if the stream cannot be positioned properly or if an I/O error occurs.

  Since:

  12

  See Also:

  • skip(long)

• available

  public int available() throwsIOException

  Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking, which may be 0, or 0 when end of stream is detected. The read might be on the same thread or another thread. A single read or skip of this many bytes will not block, but may read or skip fewer bytes.

  Note that while some implementations ofInputStream will return the total number of bytes in the stream, many will not. It is never correct to use the return value of this method to allocate a buffer intended to hold all data in this stream.

  A subclass's implementation of this method may choose to throw anIOException if this input stream has been closed by invoking theclose() method.

  API Note:

  This method should be overridden by subclasses.

  Implementation Requirements:

  Theavailable method ofInputStream always returns0.

  Returns:

  an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking or0 when it reaches the end of the input stream.

  Throws:

  IOException - if an I/O error occurs.

• close

  public void close() throwsIOException

  Closes this input stream and releases any system resources associated with the stream.

  Specified by:

  close in interface AutoCloseable

  Specified by:

  close in interface Closeable

  Implementation Requirements:

  Theclose method ofInputStream does nothing.

  Throws:

  IOException - if an I/O error occurs.

• mark

  public void mark(int readlimit)

  Marks the current position in this input stream. A subsequent call to thereset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes.

  Thereadlimit arguments tells this input stream to allow that many bytes to be read before the mark position gets invalidated.

  The general contract ofmark is that, if the methodmarkSupported returnstrue, the stream somehow remembers all the bytes read after the call tomark and stands ready to supply those same bytes again if and whenever the methodreset is called. However, the stream is not required to remember any data at all if more thanreadlimit bytes are read from the stream beforereset is called.

  Marking a closed stream should not have any effect on the stream.

  Implementation Requirements:

  Themark method ofInputStream does nothing.

  Parameters:

  readlimit - the maximum limit of bytes that can be read before the mark position becomes invalid.

  See Also:

  • reset()

• reset

  public void reset() throwsIOException

  Repositions this stream to the position at the time themark method was last called on this input stream.

  The general contract ofreset is:

  • If the methodmarkSupported returnstrue, then:
    • If the methodmark has not been called since the stream was created, or the number of bytes read from the stream sincemark was last called is larger than the argument tomark at that last call, then anIOException might be thrown.
    • If such anIOException is not thrown, then the stream is reset to a state such that all the bytes read since the most recent call tomark (or since the start of the file, ifmark has not been called) will be resupplied to subsequent callers of theread method, followed by any bytes that otherwise would have been the next input data as of the time of the call toreset.
  • If the methodmarkSupported returnsfalse, then:
    • The call toreset may throw anIOException.
    • If anIOException is not thrown, then the stream is reset to a fixed state that depends on the particular type of the input stream and how it was created. The bytes that will be supplied to subsequent callers of theread method depend on the particular type of the input stream.

  Implementation Requirements:

  The methodreset for classInputStream does nothing except throw anIOException.

  Throws:

  IOException - if this stream has not been marked or if the mark has been invalidated.

  See Also:

  • mark(int)
  • IOException

• markSupported

  public boolean markSupported()

  Tests if this input stream supports themark andreset methods. Whether or notmark andreset are supported is an invariant property of a particular input stream instance.

  Implementation Requirements:

  ThemarkSupported method ofInputStream returnsfalse.

  Returns:

  true if this stream instance supports the mark and reset methods;false otherwise.

  See Also:

  • mark(int)
  • reset()

• transferTo

  public long transferTo(OutputStream out) throwsIOException

  Reads all bytes from this input stream and writes the bytes to the given output stream in the order that they are read. On return, this input stream will be at end of stream. This method does not close either stream.

  This method may block indefinitely reading from the input stream, or writing to the output stream. The behavior for the case where the input and/or output stream isasynchronously closed, or the thread interrupted during the transfer, is highly input and output stream specific, and therefore not specified.

  If the total number of bytes transferred is greater thanLong.MAX_VALUE, thenLong.MAX_VALUE will be returned.

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

  Parameters:

  out - the output stream, non-null

  Returns:

  the number of bytes transferred

  Throws:

  IOException - if an I/O error occurs when reading or writing

  NullPointerException - ifout isnull

  Since:

  9