Constructors

Constructors

InputStream()
Declaration:
public InputStream()
Methods
read()
Declaration:
public abstract int read()
throws IOException
Description:
Reads the next byte of data from the 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
method blocks until input data is available, the end of the stream is detected, or an exception is thrown.
A subclass must provide an implementation of this method.
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(byte[])
Declaration:
public int read(byte[] b)
throws IOException
Description:
Reads some number of bytes from the input stream and stores them into the buffer array b. 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 the length of b 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[0], the next one into b[1], and so on. The number of bytes
read is, at most, equal to the length of b. Let k be the number of bytes actually read; these bytes will be
stored in elements b[0] through b[k-1], leaving elements b[k] through b[b.length-1] 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) method for class InputStream has the same effect as:
read(b, 0, b.length)
Parameters:
b - the buffer into which the data is read.

read(byte[], int, int)
Returns: the total number of bytes read into the buffer, or -1 is there is no more data because the end of
the stream has been reached.
Throws:
IOException - if an I/O error occurs.
See Also: read(byte[], int, int)
read(byte[], int, int)
Declaration:
public int read(byte[] b, int off, int len)
throws IOException
Description:
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.
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.


skip(long)
Declaration:
public long skip(long n)
throws IOException
Description:
Skips over and discards n bytes of data from this input stream. The skip method may, for a variety of
reasons, end up skipping over some smaller number of bytes, possibly 0. This may result from any of a
number of conditions; reaching end of file before n bytes have been skipped is only one possibility. The
actual number of bytes skipped is returned. If n is negative, no bytes are skipped.
The skip method of InputStream creates a byte array and then repeatedly reads into it until n 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.
Parameters:
n - the number of bytes to be skipped.
Returns: the actual number of bytes skipped.
Throws:
IOException - if an I/O error occurs.