java.io

Class LineNumberReader

Implemented Interfaces:
AutoCloseable, Closeable, Readable

public class LineNumberReader
extends BufferedReader

This class functions like a standard Reader except that it counts line numbers, and canonicalizes newline characters. As data is read, whenever the char sequences "\r", "\n", or "\r\n" are encountered, the running line count is incremeted by one. Additionally, the whatever line termination sequence was encountered will be converted to a "\n" char. Note that this class numbers lines from 0. When the first line terminator is encountered, the line number is incremented to 1, and so on. Also note that actual "\r" and "\n" characters are looked for. The system dependent line separator sequence is ignored.

This class counts only line termination characters. If the last line read from the stream does not end in a line termination sequence, it will not be counted as a line.

Field Summary

Fields inherited from class java.io.Reader

lock

Constructor Summary

LineNumberReader(Reader in)
Create a new LineNumberReader that reads from the specified subordinate Reader.
LineNumberReader(Reader in, int size)
This method initializes a new LineNumberReader to read from the specified subordinate Reader using the specified read buffer size.

Method Summary

int
getLineNumber()
This method returns the current line number
void
mark(int readLimit)
This method marks a position in the input to which the stream can be "reset" char calling the reset() method.
int
read()
This method reads an unsigned char from the input stream and returns it as an int in the range of 0-65535.
int
read(char[] buf, int offset, int count)
This method reads chars from a stream and stores them into a caller supplied buffer.
String
readLine()
This method reads a line of text from the input stream and returns it as a String.
void
reset()
This method resets a stream to the point where the mark() method was called.
void
setLineNumber(int lineNumber)
This method sets the current line number to the specified value.
long
skip(long count)
This method skips over characters in the stream.

Methods inherited from class java.io.BufferedReader

close, mark, markSupported, read, read, readLine, ready, reset, skip

Methods inherited from class java.io.Reader

close, mark, markSupported, read, read, read, read, ready, reset, skip

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

LineNumberReader

public LineNumberReader(Reader in)
Create a new LineNumberReader that reads from the specified subordinate Reader. A default 8K char sized buffer will be used for reads.
Parameters:
in - The subordinate Reader to read from

LineNumberReader

public LineNumberReader(Reader in,
                        int size)
This method initializes a new LineNumberReader to read from the specified subordinate Reader using the specified read buffer size.
Parameters:
in - The subordinate Reader to read from
size - The buffer size to use for reading

Method Details

getLineNumber

public int getLineNumber()
This method returns the current line number
Returns:
The current line number

mark

public void mark(int readLimit)
            throws IOException
This method marks a position in the input to which the stream can be "reset" char calling the reset() method. The parameter readlimit is the number of chars that can be read from the stream after setting the mark before the mark becomes invalid. For example, if mark() is called with a read limit of 10, then when 11 chars of data are read from the stream before the reset() method is called, then the mark is invalid and the stream object instance is not required to remember the mark.

In this class, this method will remember the current line number as well as the current position in the stream. When the reset() method is called, the line number will be restored to the saved line number in addition to the stream position.

Overrides:
mark in interface BufferedReader
Parameters:
readLimit - The number of chars that can be read before the mark becomes invalid
Throws:
IOException - If an error occurs

read

public int read()
            throws IOException
This method reads an unsigned char from the input stream and returns it as an int in the range of 0-65535. This method will return -1 if the end of the stream has been reached.

Note that if a line termination sequence is encountered (ie, "\r", "\n", or "\r\n") then that line termination sequence is converted to a single "\n" value which is returned from this method. This means that it is possible this method reads two chars from the subordinate stream instead of just one.

Note that this method will block until a char of data is available to be read.

Overrides:
read in interface BufferedReader
Returns:
The char read or -1 if end of stream
Throws:
IOException - If an error occurs

read

public int read(char[] buf,
                int offset,
                int count)
            throws IOException
This method reads chars from a stream and stores them into a caller supplied buffer. It starts storing data at index offset into the buffer and attemps to read len chars. This method can return before reading the number of chars requested. The actual number of chars read is returned as an int. A -1 is returned to indicated the end of the stream.

This method will block until some data can be read.

Note that if a line termination sequence is encountered (ie, "\r", "\n", or "\r\n") then that line termination sequence is converted to a single "\n" value which is stored in the buffer. Only a single char is counted towards the number of chars read in this case.

Overrides:
read in interface BufferedReader
Parameters:
buf - The array into which the chars read should be stored
offset - The offset into the array to start storing chars
count - The requested number of chars to read
Returns:
The actual number of chars read, or -1 if end of stream
Throws:
IOException - If an error occurs.
NullPointerException - If buf is null (in any case).
IndexOutOfBoundsException - If buffer parameters (offset and count) lies outside of the buffer capacity.

readLine

public String readLine()
            throws IOException
This method reads a line of text from the input stream and returns it as a String. A line is considered to be terminated by a "\r", "\n", or "\r\n" sequence, not by the system dependent line separator.
Overrides:
readLine in interface BufferedReader
Returns:
The line read as a String or null if end of stream.
Throws:
IOException - If an error occurs

reset

public void reset()
            throws IOException
This method resets a stream to the point where the mark() method was called. Any chars that were read after the mark point was set will be re-read during subsequent reads.

In this class, this method will also restore the line number that was current when the mark() method was called.

Overrides:
reset in interface BufferedReader
Throws:
IOException - If an error occurs

setLineNumber

public void setLineNumber(int lineNumber)
This method sets the current line number to the specified value.
Parameters:
lineNumber - The new line number

skip

public long skip(long count)
            throws IOException
This method skips over characters in the stream. This method will skip the specified number of characters if possible, but is not required to skip them all. The actual number of characters skipped is returned. This method returns 0 if the specified number of chars is less than 1.
Overrides:
skip in interface BufferedReader
Parameters:
count - The specified number of chars to skip.
Returns:
The actual number of chars skipped.
Throws:
IOException - If an error occurs

LineNumberReader.java -- A character input stream which counts line numbers Copyright (C) 1998, 1999, 2001, 2003, 2005 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.