java.io
Class LineNumberInputStream

java.lang.Object
  |
  +--java.io.InputStream
        |
        +--java.io.FilterInputStream
              |
              +--java.io.LineNumberInputStream

public class LineNumberInputStream

extends FilterInputStream

An input stream that keeps track of line numbers.

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

LineNumberInputStream(InputStream in)
Constructs a new LineNumberInputStream initialized with the specified input stream.

Method Summary

int	available() Returns the number of bytes that can be read without blocking.
int	getLineNumber() Returns the current line number.
void	mark(int readlimit) Marks the current position in the input stream.
int	read() Reads a byte of data.
int	read(byte[] b, int off, int len) Reads into an array of bytes.
void	reset() Repositions the stream to the last marked position.
void	setLineNumber(int lineNumber) Sets the current line number.
long	skip(long n) Skips n bytes of input.

Methods inherited from class java.io.FilterInputStream

close, markSupported, read

Methods inherited from class java.lang.Object

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

Constructor Detail

LineNumberInputStream

public LineNumberInputStream(InputStream in)

Constructs a new LineNumberInputStream initialized with the specified input stream.

Parameters:

in - the input stream

Method Detail

read

public int read()
         throws IOException

Reads a byte of data. The method will block if no input is available.

Overrides:

read in class FilterInputStream

Returns:

the byte read, or -1 if the end of the stream is reached.

Throws:

IOException - If an I/O error has occurred.

read

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

Reads into an array of bytes. This method will blocks until some input is available.

Overrides:

read in class FilterInputStream

Parameters:

b - the buffer into which the data is read

off - the start offset of the data

len - the maximum number of bytes read

Returns:

the actual number of bytes read, -1 is returned when the end of the stream is reached.

Throws:

IOException - If an I/O error has occurred.

setLineNumber

public void setLineNumber(int lineNumber)

Sets the current line number.

Parameters:

lineNumber - the line number to be set

getLineNumber

public int getLineNumber()

Returns the current line number.

skip

public long skip(long n)
          throws IOException

Skips n bytes of input.

Overrides:

skip in class FilterInputStream

Parameters:

n - the number of bytes to be skipped

Returns:

the actual number of bytes skipped.

Throws:

IOException - If an I/O error has occurred.

available

public int available()
              throws IOException

Returns the number of bytes that can be read without blocking.

Overrides:

available in class FilterInputStream

Returns:

the number of available bytes

IOException

mark

public void mark(int readlimit)

Marks the current position in the input stream. A subsequent call to reset() will reposition the stream at the last marked position so that subsequent reads will re-read the same bytes. The stream promises to allow readlimit bytes to be read before the mark position gets invalidated.

Overrides:

mark in class FilterInputStream

Parameters:

readlimit - the maximum limit of bytes allowed to be read before the mark position becomes invalid.

reset

public void reset()
           throws IOException

Repositions the stream to the last marked position. If the stream has not been marked, or if the mark has been invalidated, an IOException is thrown. Stream marks are intended to be used in situations where you need to read ahead a little to see what's in the stream. Often this is most easily done by invoking some general parser. If the stream is of the type handled by the parser, it just chugs along happily. If the stream is not of that type, the parser should toss an exception when it fails, which, if it happens within readlimit bytes, allows the outer code to reset the stream and try another parser.

Overrides:

reset in class FilterInputStream

Throws:

IOException - If the stream has not been marked or if the mark has been invalidated.