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.

Methods declared in class InputStream

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

Modifier and Type	Method	Description
void	mark(int readlimit)	Marks the current position in this input stream.
boolean	markSupported()	Tests if this input stream supports the mark and reset methods.
static InputStream	nullInputStream()	Returns a new InputStream that reads no bytes.
int	read(byte[] b)	Reads some number of bytes from the input stream and stores them into the buffer array b.
byte[]	readAllBytes()	Reads all remaining bytes from the input stream.
int	readNBytes(byte[] b, int off, int len)	Reads the requested number of bytes from the input stream into the given byte array.
byte[]	readNBytes(int len)	Reads up to a specified number of bytes from the input stream.
void	reset()	Repositions this stream to the position at the time the mark method was last called on this input stream.
long	skip(long n)	Skips over and discards n bytes of data from this input stream.
void	skipNBytes(long n)	Skips over and discards exactly n bytes of data from this input stream.
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 declared in class Object

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

Modifier and Type	Method	Description
protected Object	clone()	Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
boolean	equals(Object o)	Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. May cause performance issues, deadlocks and hangs.
final Class<? extends Object>	getClass()	Answers the unique instance of java.lang.Class which represents the class of the receiver.
int	hashCode()	Answers an integer hash code for the receiver.
final void	notify()	Causes one thread which is waiting on the receiver to be made ready to run.
final void	notifyAll()	Causes all threads which are waiting on the receiver to be made ready to run.
String	toString()	Answers a string containing a concise, human-readable description of the receiver.
final void	wait()	Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by notify or notifyAll).
final void	wait(long time)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.
final void	wait(long time, int frac)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.

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.