student.testingsupport

Class MutableStringBufferInputStream

java.lang.Object

java.io.InputStream

student.testingsupport.MutableStringBufferInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public class MutableStringBufferInputStream
extends InputStream

A custom input stream that takes its contents from a provided string literal, and that also supports dynamically resetting of its own contents. This class is designed to help write test cases involving input, particularly from System.in. It can be used as a "smart" replacement for System.in that allows the console input to be provided by string contents, and allows the console input to be reset whenever needed.

Note that it is possible to create a MutableStringBufferInputStream with null contents. Such a stream is in an "unusable" state where no InputStream methods can be called until actual contents have been provided at some later point. Any calls to InputStream methods when a stream is unusable are instead preempted, and a protected error handling method called handleMissingContents() is invoked instead, usually producing an IllegalStateException. The handleMissingContents() method is protected, so that subclasses can override it to provide customized error responses if desired.

At any point in time, resetContents(String) (or resetContents(InputStream)) can be used to change the stream's contents to a new value. This completely resets the stream's state.

Version:

$Revision: 1.3 $, $Date: 2010/02/23 17:06:38 $

Author:

Stephen Edwards, Last changed by $Author: stedwar2 $

Constructor Summary

Constructors

Constructor and Description
MutableStringBufferInputStream(InputStream contents) Create a new input stream with the specified contents.
MutableStringBufferInputStream(String contents) Create a new input stream with the specified contents.

Method Summary

Modifier and Type	Method and Description
int	available()
String	getName() Get the human-readable name of this input stream, for diagnostic or debugging purposes.
protected void	handleMissingContents() Handle access to an input stream that has not had its contents defined.
int	read()
int	read(byte[] b, int off, int len)
void	reset()
void	resetContents(InputStream newContents) Reset this stream and replace its contents.
void	resetContents(String newContents) Reset this stream and replace its contents.
void	setName(String name) Set the human-readable name of this input stream, for diagnostic or debugging purposes.
long	skip(long n)

Methods inherited from class java.io.InputStream

close, mark, markSupported, read

Methods inherited from class java.lang.Object

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

Constructor Detail

MutableStringBufferInputStream

public MutableStringBufferInputStream(String contents)

Create a new input stream with the specified contents. If null is provided, the stream is created in an "unusable" state where InputStream methods cannot be called until actual contents have been provided at some later point. Any attempt to access an unusable stream is preempted by a call to handleMissingContents(), which typically produces an exception. Contents can be changed at any time using resetContents().

Parameters:

contents - The complete contents of this input stream, provided as a String.

MutableStringBufferInputStream

public MutableStringBufferInputStream(InputStream contents)

Create a new input stream with the specified contents. If null is provided, the stream is created in an "unusable" state where InputStream methods cannot be called until actual contents have been provided at some later point. Any attempt to access an unusable stream is preempted by a call to handleMissingContents(), which typically produces an exception. Contents can be changed at any time using resetContents().

Parameters:

contents - A second input stream to draw contents from. All stream operations will be delegated to this object, until resetContents() is called.

Method Detail

getName

public String getName()

Get the human-readable name of this input stream, for diagnostic or debugging purposes. The default name for each newly-created stream is simply "an input stream", but a specific name can be provided using setName(String) where desired.

Returns:

This stream's name, for debugging purposes.

setName

public void setName(String name)

Set the human-readable name of this input stream, for diagnostic or debugging purposes. The default name is simply "an input stream".

Parameters:

name - The new name to use for this stream.

resetContents

public void resetContents(String newContents)

Reset this stream and replace its contents. If null is provided, the stream becomes "unusable" where InputStream methods cannot be called until actual contents have been provided at some later point. Any attempt to access an unusable stream is preempted by a call to handleMissingContents(), which typically produces an exception. Contents can be changed again at any time using resetContents().

Parameters:

newContents - The new contents (possibly null) for this stream.

resetContents

public void resetContents(InputStream newContents)

Reset this stream and replace its contents. If null is provided, the stream becomes "unusable" where InputStream methods cannot be called until actual contents have been provided at some later point. Any attempt to access an unusable stream is preempted by a call to handleMissingContents(), which typically produces an exception. Contents can be changed again at any time using resetContents().

Parameters:

newContents - The new contents (possibly null) for this stream.

handleMissingContents

protected void handleMissingContents()

Handle access to an input stream that has not had its contents defined. The default behavior is to throw an IllegalStateException indicating that the stream has not had its contents set. Subclasses can override this method to provide custom error handling behaviors as needed.

read

public int read()
         throws IOException

Specified by:

read in class InputStream

Throws:

IOException

read

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

Overrides:

read in class InputStream

Throws:

IOException

skip

public long skip(long n)
          throws IOException

Overrides:

skip in class InputStream

Throws:

IOException

available

public int available()
              throws IOException

Overrides:

available in class InputStream

Throws:

IOException

reset

public void reset()
           throws IOException

Overrides:

reset in class InputStream

Throws:

IOException