java.io
Class SequenceInputStream

java.lang.Object
  java.io.InputStream
      java.io.SequenceInputStream

public class SequenceInputStream

extends InputStream

A SequenceInputStream represents the logical concatenation of other input streams. It starts out with an ordered collection of input streams and reads from the first one until end of file is reached, whereupon it reads from the second one, and so on, until end of file is reached on the last of the contained input streams.

Since:

JDK1.0

Author:

Author van Hoff

Field Summary

(package private) Enumeration	e
(package private) InputStream	in

Fields inherited from class java.io.InputStream

Constructor Summary

SequenceInputStream(Enumeration e)
Initializes a newly created SequenceInputStream by remembering the argument, which must be an Enumeration that produces objects whose run-time type is InputStream.

SequenceInputStream(InputStream s1, InputStream s2)
Initializes a newly created SequenceInputStream by remembering the two arguments, which will be read in order, first s1 and then s2, to provide the bytes to be read from this SequenceInputStream.

Method Summary

int	available() Returns the number of bytes available on the current stream.
void	close() Closes this input stream and releases any system resources associated with the stream.
(package private) void	nextStream() Continues reading in the next stream if an EOF is reached.
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 from this 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

Field Detail

e

Enumeration e

in

InputStream in

Constructor Detail

SequenceInputStream

public SequenceInputStream(Enumeration e)

Initializes a newly created SequenceInputStream by remembering the argument, which must be an Enumeration that produces objects whose run-time type is InputStream. The input streams that are produced by the enumeration will be read, in order, to provide the bytes to be read from this SequenceInputStream. After each input stream from the enumeration is exhausted, it is closed by calling its close method.

Parameters:

e - an enumeration of input streams.

See Also:

Enumeration

SequenceInputStream

public SequenceInputStream(InputStream s1,
                           InputStream s2)

Initializes a newly created SequenceInputStream by remembering the two arguments, which will be read in order, first s1 and then s2, to provide the bytes to be read from this SequenceInputStream.

Parameters:

s1 - the first input stream to read.

s2 - the second input stream to read.

Method Detail

nextStream

final void nextStream()
               throws IOException

Continues reading in the next stream if an EOF is reached.

Throws:

IOException

available

public int available()
              throws IOException

Returns the number of bytes available on the current stream.

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.

Since:

JDK1.1

read

public int read()
         throws IOException

Reads the next byte of data from this input stream. The 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.

This method tries to read one character from the current substream. If it reaches the end of the stream, it calls the close method of the current substream and begins reading from the next substream.

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.

read

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

Reads up to len bytes of data from this input stream into an array of bytes. This method blocks until at least 1 byte of input is available. If the first argument is null, up to len bytes are read and discarded.

The read method of SequenceInputStream tries to read the data from the current substream. If it fails to read any characters because the substream has reached the end of the stream, it calls the close method of the current substream and begins reading from the next substream.

Overrides:

read in class InputStream

Parameters:

b - the buffer into which the data is read.

off - the start offset of the data.

len - the maximum number of bytes read.

Returns:

int the number of bytes read.

Throws:

IOException - if an I/O error occurs.

See Also:

InputStream.read()

close

public void close()
           throws IOException

Closes this input stream and releases any system resources associated with the stream. A closed SequenceInputStream cannot perform input operations and cannot be reopened.

If this stream was created from an enumeration, all remaining elements are requested from the enumeration and closed before the close method returns. of InputStream .

Overrides:

close in class InputStream

Throws:

IOException - if an I/O error occurs.