NullInputStream

A functional, light weight {@link InputStream} that emulates a stream of a specified size.

This implementation provides a light weight object for testing with an {@link InputStream} where the contents don't matter.

One use case would be for testing the handling of large {@link InputStream} as it can emulate that scenario without the overhead of actually processing large numbers of bytes - significantly speeding up test execution times.

This implementation returns zero from the method that reads a byte and leaves the array unchanged in the read methods that are passed a byte array. If alternative data is required the processByte() and processBytes() methods can be implemented to generate data, for example:

  public class TestInputStream extends NullInputStream {
      public TestInputStream(int size) {
          super(size);
      }
      protected int processByte() {
          return ... // return required value here
      }
      protected void processBytes(byte[] bytes, int offset, int length) {
          for (int i = offset; i < length; i++) {
              bytes[i] = ... // set array value here
          }
      }
  }

Since: Commons IO 1.3

Version: $Revision: 463529 $

Field Summary
boolean	eof
long	mark
boolean	markSupported
long	position
long	readlimit
long	size
boolean	throwEofException

Constructor Summary
	NullInputStream(long size) Create an {@link InputStream} that emulates a specified size which supports marking and does not throw EOFException.
	NullInputStream(long size, boolean markSupported, boolean throwEofException) Create an {@link InputStream} that emulates a specified size with option settings.

Method Summary
int	available() Return the number of bytes that can be read.
void	close() Close this input stream - resets the internal state to the initial values.
int	doEndOfFile() Handle End of File.
long	getPosition() Return the current position.
long	getSize() Return the size this {@link InputStream} emulates.
void	mark(int readlimit) Mark the current position.
boolean	markSupported() Indicates whether mark is supported.
protected int	processByte() Return a byte value for the `read()` method.
protected void	processBytes(byte[] bytes, int offset, int length) Process the bytes for the `read(byte[], offset, length)` method.
int	read() Read a byte.
int	read(byte[] bytes) Read some bytes into the specified array.
int	read(byte[] bytes, int offset, int length) Read the specified number bytes into an array.
void	reset() Reset the stream to the point when mark was last called.
long	skip(long numberOfBytes) Skip a specified number of bytes.

Create an {@link InputStream} that emulates a specified size with option settings.

Parameters: size The size of the input stream to emulate. markSupported Whether this instance will support the mark() functionality. throwEofException Whether this implementation will throw an {@link EOFException} or return -1 when the end of file is reached.

Method Detail

available

doEndOfFile

Handle End of File.

Returns: -1 if throwEofException is set to false

Throws: EOFException if throwEofException is set to true.

Process the bytes for the read(byte[], offset, length) method.

This implementation leaves the byte array unchanged.

Parameters: bytes The byte array offset The offset to start at. length The number of bytes.

read

Read a byte.

Returns: Either The byte value returned by processByte() or -1 if the end of file has been reached and throwEofException is set to false.

Throws: EOFException if the end of file is reached and throwEofException is set to true. IOException if trying to read past the end of file.

read

Read some bytes into the specified array.

Parameters: bytes The byte array to read into

Returns: The number of bytes read or -1 if the end of file has been reached and throwEofException is set to false.

Throws: EOFException if the end of file is reached and throwEofException is set to true. IOException if trying to read past the end of file.

read

Read the specified number bytes into an array.

Parameters: bytes The byte array to read into. offset The offset to start reading bytes into. length The number of bytes to read.

Returns: The number of bytes read or -1 if the end of file has been reached and throwEofException is set to false.

Throws: EOFException if the end of file is reached and throwEofException is set to true. IOException if trying to read past the end of file.

reset

skip

Skip a specified number of bytes.

Parameters: numberOfBytes The number of bytes to skip.

Returns: The number of bytes skipped or -1 if the end of file has been reached and throwEofException is set to false.

Throws: EOFException if the end of file is reached and throwEofException is set to true. IOException if trying to read past the end of file.

Class NullInputStream