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## java.io
Class LineNumberReader

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

All Implemented Interfaces:
  Closeable, Readable

    public class LineNumberReader

extends BufferedReader

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

By default, line numbering begins at 0. This number increments as 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

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.

### 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()`

### getLineNumber

    public int getLineNumber()

  Get the current line number.

  Returns:
    The current line number.
  See Also:
    `setLineNumber(int)`

### read

    public int read()
             throws IOException

  Read a single character. Line terminators are compressed into single newline ('\n') characters.

  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

### read

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

  Read characters into a portion of an array.

  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

### readLine

    public String readLine()
                    throws IOException

  Read a line of text. 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.

  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

### 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

### 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

### 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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For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2004 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.