public class

SequenceInputStream

extends InputStream
java.lang.Object
   ↳ java.io.InputStream
     ↳ java.io.SequenceInputStream

Class Overview

Concatenates two or more existing InputStreams. Reads are taken from the first stream until it ends, then the next stream is used, until the last stream returns end of file.

Summary

Public Constructors
SequenceInputStream(InputStream s1, InputStream s2)
Constructs a new SequenceInputStream using the two streams s1 and s2 as the sequence of streams to read from.
SequenceInputStream(Enumeration<? extends InputStream> e)
Constructs a new SequenceInputStream using the elements returned from Enumeration e as the stream sequence.
Public Methods
int available()
Returns the number of bytes that are available before the current input stream will block.
void close()
Closes all streams in this sequence of input stream.
int read(byte[] buffer, int offset, int count)
Reads at most count bytes from this sequence of input streams and stores them in the byte array buffer starting at offset.
int read()
Reads a single byte from this sequence of input streams and returns it as an integer in the range from 0 to 255.
[Expand]
Inherited Methods
From class java.io.InputStream
From class java.lang.Object
From interface java.io.Closeable

Public Constructors

public SequenceInputStream (InputStream s1, InputStream s2)

Since: API Level 1

Constructs a new SequenceInputStream using the two streams s1 and s2 as the sequence of streams to read from.

Parameters
s1 the first stream to get bytes from.
s2 the second stream to get bytes from.
Throws
NullPointerException if s1 is null.

public SequenceInputStream (Enumeration<? extends InputStream> e)

Since: API Level 1

Constructs a new SequenceInputStream using the elements returned from Enumeration e as the stream sequence. The instances returned by e.nextElement() must be of type InputStream.

Parameters
e the enumeration of InputStreams to get bytes from.
Throws
NullPointerException if any of the elements in e is null.

Public Methods

public int available ()

Since: API Level 1

Returns the number of bytes that are available before the current input stream will block.

Returns
  • the number of bytes available in the current input stream before blocking.
Throws
IOException if an I/O error occurs in the current input stream.

public void close ()

Since: API Level 1

Closes all streams in this sequence of input stream.

Throws
IOException if an error occurs while closing any of the input streams.

public int read (byte[] buffer, int offset, int count)

Since: API Level 1

Reads at most count bytes from this sequence of input streams and stores them in the byte array buffer starting at offset. Blocks only until at least 1 byte has been read, the end of the stream has been reached, or an exception is thrown.

This SequenceInputStream shows the same behavior as other InputStreams. To do this it will read only as many bytes as a call to read on the current substream returns. If that call does not return as many bytes as requested by count, it will not retry to read more on its own because subsequent reads might block. This would violate the rule that it will only block until at least one byte has been read.

If a substream has already reached the end when this call is made, it will close that substream and start with the next one. If there are no more substreams it will return -1.

Parameters
buffer the array in which to store the bytes read.
offset the initial position in buffer to store the bytes read from this stream.
count the maximum number of bytes to store in buffer.
Returns
  • the number of bytes actually read; -1 if this sequence of streams is closed or if the end of the last stream in the sequence has been reached.
Throws
IndexOutOfBoundsException if offset < 0 or count < 0, or if offset + count is greater than the size of buffer.
IOException if an I/O error occurs.
NullPointerException if buffer is null.

public int read ()

Since: API Level 1

Reads a single byte from this sequence of input streams and returns it as an integer in the range from 0 to 255. It tries to read from the current stream first; if the end of this stream has been reached, it reads from the next one. Blocks until one byte has been read, the end of the last input stream in the sequence has been reached, or an exception is thrown.

Returns
  • the byte read or -1 if either the end of the last stream in the sequence has been reached or this input stream sequence is closed.
Throws
IOException if an error occurs while reading the current source input stream.