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java.io
Class LineNumberReader

java.lang.Object
 extended by java.io.Reader
 extended by java.io.BufferedReader
 extended by java.io.LineNumberReader

All Implemented Interfaces:

Closeable, Readable

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public class LineNumberReader
extends BufferedReader

A buffered character-input stream that keeps track of line numbers. This class defines methods setLineNumber(int) and getLineNumber() for setting and getting the current line number respectively.

By default, line numbering begins at 0. This number increments at every line terminator as the data is read, and can be changed with a call to setLineNumber(int). Note however, that setLineNumber(int) does not actually change the current position in the stream; it only changes the value that will be returned by getLineNumber().

A line is considered to be terminated by any one of a line feed ('\n'), a carriage return ('\r'), or a carriage return followed immediately by a linefeed.

Since:

JDK1.1

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Field Summary

Fields inherited from class java.io.Reader
lock

Constructor Summary
LineNumberReader(Reader in) Create a new line-numbering reader, using the default input-buffer size.
LineNumberReader(Reader in, int sz) Create a new line-numbering reader, reading characters into a buffer of the given size.

Method Summary
int	getLineNumber() Get the current line number.
void	mark(int readAheadLimit) Mark the present position in the stream.
int	read() Read a single character.
int	read(char[] cbuf, int off, int len) Read characters into a portion of an array.
String	readLine() Read a line of text.
void	reset() Reset the stream to the most recent mark.
void	setLineNumber(int lineNumber) Set the current line number.
long	skip(long n) Skip characters.

Methods inherited from class java.io.BufferedReader
close, markSupported, ready

Methods inherited from class java.io.Reader
read, read

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LineNumberReader

public LineNumberReader(Reader in)

Create a new line-numbering reader, using the default input-buffer size.

Parameters:

in - A Reader object to provide the underlying stream

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LineNumberReader

public LineNumberReader(Reader in,
 int sz)

Create a new line-numbering reader, reading characters into a buffer of the given size.

Parameters:

in - A Reader object to provide the underlying stream

sz - An int specifying the size of the buffer

Method Detail

setLineNumber

public void setLineNumber(int lineNumber)

Set the current line number.

Parameters:

lineNumber - An int specifying the line number

See Also:

getLineNumber()

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getLineNumber

public int getLineNumber()

Get the current line number.

Returns:

The current line number

See Also:

setLineNumber(int)

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read

public int read()
 throws IOException

Read a single character. Line terminators are compressed into single newline ('\n') characters. Whenever a line terminator is read the current line number is incremented.

Overrides:

read in class BufferedReader

Returns:

The character read, or -1 if the end of the stream has been reached

Throws:

IOException - If an I/O error occurs

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read

public int read(char[] cbuf,
 int off,
 int len)
 throws IOException

Read characters into a portion of an array. Whenever a line terminator is read the current line number is incremented.

Overrides:

read in class BufferedReader

Parameters:

cbuf - Destination buffer

off - Offset at which to start storing characters

len - Maximum number of characters to read

Returns:

The number of bytes read, or -1 if the end of the stream has already been reached

Throws:

IOException - If an I/O error occurs

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readLine

public String readLine()
 throws IOException

Read a line of text. Whenever a line terminator is read the current line number is incremented.

Overrides:

readLine in class BufferedReader

Returns:

A String containing the contents of the line, not including any line termination characters, or null if the end of the stream has been reached

Throws:

IOException - If an I/O error occurs

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skip

public long skip(long n)
 throws IOException

Skip characters.

Overrides:

skip in class BufferedReader

Parameters:

n - The number of characters to skip

Returns:

The number of characters actually skipped

Throws:

IOException - If an I/O error occurs

IllegalArgumentException - If n is negative

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mark

public void mark(int readAheadLimit)
 throws IOException

Mark the present position in the stream. Subsequent calls to reset() will attempt to reposition the stream to this point, and will also reset the line number appropriately.

Overrides:

mark in class BufferedReader

Parameters:

readAheadLimit - Limit on the number of characters that may be read while still preserving the mark. After reading this many characters, attempting to reset the stream may fail.

Throws:

IOException - If an I/O error occurs

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reset

public void reset()
 throws IOException

Reset the stream to the most recent mark.

Overrides:

reset in class BufferedReader

Throws:

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

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