lejos.nxt.comm
Class NXTInputStream

java.lang.Object
  java.io.InputStream
      lejos.nxt.comm.NXTInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public class NXTInputStream
extends InputStream

Extends InputStream for BlueTooth; implements available()

Author:

Roger Glassey revised on june 23, 2007, modified for Bluetooth2

Method Summary

int	available() returns the number of bytes in the input buffer - can be read without blocking
void	close() the stream is restored to its original state - ready to receive more data.
int	read() Returns one byte as an integer between 0 and 255.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from the input stream into an array of bytes.

Methods inherited from class java.io.InputStream

mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

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

Method Detail

read

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

Description copied from class: InputStream

Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read, possibly zero. 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 b is null, a NullPointerException is thrown.

If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException is thrown.

If len is zero, then no bytes are read and 0 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 into b.

The first byte read is stored into element b[off], the next one into 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.

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

If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

The read(b, off, len) method for class InputStream simply calls the method read() repeatedly. If the first such call results in an IOException, that exception is returned from the call to the read(b, off, len) method. If any subsequent call to read() results in a IOException, the exception is caught and treated as if it were end of file; the bytes read up to that point are stored into b and the number of bytes read before the exception occurred is returned. Subclasses are encouraged to provide a more efficient implementation of this method.

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:

IOException - if an I/O error occurs.

See Also:

InputStream.read()

read

public int read()
         throws IOException

Returns one byte as an integer between 0 and 255. Returns -1 if the end of the stream is reached. Does not return till some bytes are available.

Specified by:

read in class InputStream

Returns:

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

Throws:

IOException - if an I/O error occurs.

available

public int available()
              throws IOException

returns the number of bytes in the input buffer - can be read without blocking

Overrides:

available in class InputStream

Returns:

the number of bytes that can be read from this input stream without blocking.

Throws:

IOException - if an I/O error occurs.

close

public void close()

the stream is restored to its original state - ready to receive more data.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class InputStream