Chapter 11
The java.io Package

SequenceInputStream

Name

SequenceInputStream

Synopsis

Class Name:

java.io.SequenceInputStream

Superclass:

java.io.InputStream

Immediate Subclasses:

None

Interfaces Implemented:

None

Availability:

JDK 1.0 or later

The SequenceInputStream class allows a series of InputStream objects to be seamlessly concatenated into one stream. In other words, a SequenceInputStream appears and functions as a single InputStream. Internally, however, the SequenceInputStream reads data from each InputStream in the specified order. When the end of a stream is encountered, data is automatically read from the next stream.

Class Summary

public class java.io.SequenceInputStream extends java.io.InputStream {
  // Constructors
  public SequenceInputStream(Enumeration e);
  public SequenceInputStream(InputStream s1, InputStream s2);
  // Instance Methods
  public int available();                         // New in 1.1
  public void close();
  public int read();
  public int read(byte[] buf, int pos, int len);
}

Constructors

SequenceInputStream

public SequenceInputStream(Enumeration e)

Parameters

e: An Enumeration of input streams.

Description

This constructor creates a SequenceInputStream that reads from each of the InputStream objects in the given Enumeration. Each object in the Enumeration must be an InputStream.

public SequenceInputStream(InputStream s1, InputStream s2)

Parameters

s1

An input stream.

s2

Another input stream.

Description

This constructor creates a SequenceInputStream that reads first from s1 and then from s2.

Instance Methods

available

public int available() throws IOException

Availability

New as of JDK 1.1

Returns

The number of bytes that can be read without blocking, or 0 if the end of the final stream is encountered.

Throws

IOException: If any kind of I/O error occurs.

Overrides

InputStream.available()

Description

This method returns the number of bytes that can be read without having to wait for more data to become available. The method returns the result of calling available() on the current stream. If the end of the final stream is encountered, the method returns 0.

close

public void close() throws IOException

Throws

IOException: If any kind of I/O error occurs.

Overrides

InputStream.close()

Description

This method closes the stream and releases the system resources that are associated with it. The method closes all the InputStream objects attached to this object.

read

public int read() throws IOException

Returns

The next byte of data or -1 if the end of the final stream is encountered.

Throws

IOException: If any kind of I/O error occurs.

Overrides

InputStream.read()

Description

This method reads the next byte of data from the current stream. When the end of the current stream is encountered, that stream is closed, and the first byte of the next InputStream is read. If there are no more InputStream objects in the SequenceInputStream, -1 is returned to signify the end of the SequenceInputStream. The method blocks until the byte is read, the end of the final stream is encountered, or an exception is thrown.

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

Parameters

buf

An array of bytes to be filled from the stream.

off

An offset into the byte array.

len

The number of bytes to read.

Returns

The actual number of bytes read or -1 if the end of the final stream is encountered immediately.

Throws

IOException: If any kind of I/O error occurs.

Overrides

InputStream.read(byte[], int, int)

Description

This method reads up to len bytes of input from the current stream into the given array starting at index off. When the end of the current stream is encountered, that stream is closed, and bytes are read from the next InputStream. If there are no more InputStream objects in the SequenceInputStream, -1 is returned to signify the end of the SequenceInputStream. The method blocks until there is some data available.

Inherited Methods

Method	Inherited From	Method	Inherited From
`clone()`	`Object`	`equals(Object)`	`Object`
`finalize()`	`Object`	`getClass()`	`Object`
`hashCode()`	`Object`	`mark(int)`	`InputStream`
`markSupported()`	`InputStream`	`notify()`	`Object`
`notifyAll()`	`Object`	`reset()`	`InputStream`
`skip(long)`	`InputStream`	`toString()`	`Object`
`wait()`	`Object`	`wait(long)`	`Object`
`wait(long, int)`	`Object`