Class SequenceInputStream

java.lang.Object

java.io.InputStream

java.io.SequenceInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

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:

1.0

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	Description
int	available()	Returns an estimate of the number of bytes that can be read (or skipped over) from the current underlying input stream without blocking by the next invocation of a method for the current underlying input stream.
void	close()	Closes this input stream and releases any system resources associated with the stream.
int	read()	Reads the next byte of data from the 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.
long	transferTo(OutputStream out)	Reads all bytes from this input stream and writes the bytes to the given output stream in the order that they are read.

Methods inherited from class java.io.InputStream

mark, markSupported, nullInputStream, read, readAllBytes, readNBytes, readNBytes, reset, skip, skipNBytes

Methods inherited from class java.lang.Object

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

Constructor Details

SequenceInputStream

public SequenceInputStream(Enumeration<? extends InputStream> 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 Details

available

public int available()
              throws IOException

Returns an estimate of the number of bytes that can be read (or skipped over) from the current underlying input stream without blocking by the next invocation of a method for the current underlying input stream. The next invocation might be 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.

This method simply calls available of the current underlying input stream and returns the result.

Overrides:

available in class InputStream

Returns:

an estimate of the number of bytes that can be read (or skipped over) from the current underlying input stream without blocking or 0 if this input stream has been closed by invoking its close() method

Throws:

IOException - if an I/O error occurs.

Since:

1.1

read

public int read()
         throws IOException

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.

This method tries to read one byte 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. If the end of the last contained stream has been reached then -1 is returned. Otherwise, if len is not zero, the method blocks until at least 1 byte of input is available; if len is zero, no bytes are read and 0 is returned.

The read method of SequenceInputStream tries to read the data from the current substream. If it fails to read any bytes 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 in array b at which the data is written.

len - the maximum number of bytes read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the last contained stream has been reached.

Throws:

NullPointerException - if the end of the last contained stream has not been reached and b is null.

IndexOutOfBoundsException - if the end of the last contained stream has not been reached and off is negative, len is negative, or len is greater than b.length - off

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.

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.

transferTo

public long transferTo(OutputStream out)
                throws IOException

Description copied from class: InputStream

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 is asynchronously 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 than Long.MAX_VALUE, then Long.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.

Overrides:

transferTo in class InputStream

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