repast.simphony.integration
Class RandomAccessWriter

java.lang.Object
  java.io.Writer
      java.io.PrintWriter
          repast.simphony.integration.RandomAccessWriter

All Implemented Interfaces:

Closeable, Flushable, Appendable

public class RandomAccessWriter
extends PrintWriter

A PrintWriter that writes to a file channel, allowing it to do random access types of writes. This supports a stack of marks (and therefore resets). It also allows for jumping to offsets in the file, determining the current file offset, and truncating the file.

Author:

Jerry Vos

Field Summary

Fields inherited from class java.io.PrintWriter

out

Fields inherited from class java.io.Writer

lock

Constructor Summary

RandomAccessWriter(File file)
Opens this writer on the specified file.

RandomAccessWriter(String fileName)
Opens this writer on the specified file.

Method Summary

void	close()
long	getTrueOffset() Retrieves the actual offset of the file, disregarding any buffering.
void	mark() Adds a mark to the mark queue at the current location in the file.
Long	popMark() Removes a mark from the mark queue and returns it.
void	position(long position) Positions the file to the specified position.
void	reset() This jumps the file offset back to the previously marked position.
FileChannel	truncate(long size) Truncates the file to the specified size.
FileChannel	truncateToPosition() Truncates the file to the current offset.

Methods inherited from class java.io.PrintWriter

append, append, append, checkError, clearError, flush, format, format, print, print, print, print, print, print, print, print, print, printf, printf, println, println, println, println, println, println, println, println, println, println, setError, write, write, write, write, write

Methods inherited from class java.lang.Object

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

Constructor Detail

RandomAccessWriter

public RandomAccessWriter(File file)
                   throws FileNotFoundException

Opens this writer on the specified file.

Parameters:

file - the file to write to

Throws:

FileNotFoundException

RandomAccessWriter

public RandomAccessWriter(String fileName)
                   throws FileNotFoundException

Opens this writer on the specified file.

Parameters:

fileName - the name of the file to open

Throws:

FileNotFoundException

Method Detail

getTrueOffset

public long getTrueOffset()
                   throws IOException

Retrieves the actual offset of the file, disregarding any buffering. A result of this call is that all buffered data is flushed before this function returns.

Returns:

the current offset of the file

Throws:

IOException

mark

public void mark()
          throws IOException

Adds a mark to the mark queue at the current location in the file. Since this used getTrueOffset(), this causes the underlying data stream to flush.

Throws:

IOException

popMark

public Long popMark()

Removes a mark from the mark queue and returns it.

Returns:

the top of the mark queue

reset

public void reset()
           throws IOException

This jumps the file offset back to the previously marked position. This does not check if the mark stack is empty, so when calling this with an empty mark stack, an exception will be thrown. This does not pop the mark that was used off the stack.

Throws:

IOException

position

public void position(long position)
              throws IOException

Positions the file to the specified position.

Parameters:

position - the position to set the write mark to

Throws:

IOException

truncateToPosition

public FileChannel truncateToPosition()
                               throws IOException

Truncates the file to the current offset. This is the same as using truncate(long) with the value from getTrueOffset().

Returns:

the truncated channel

Throws:

IOException

truncate

public FileChannel truncate(long size)
                     throws IOException

Truncates the file to the specified size.

Parameters:

size - the size to truncate the file to

Returns:

the truncated channel

Throws:

IOException

close

public void close()

Specified by:

close in interface Closeable

Overrides:

close in class PrintWriter