Class LineNumberReader

java.lang.Object
java.io.Reader
java.io.BufferedReader
java.io.LineNumberReader
All Implemented Interfaces:
Closeable,AutoCloseable,Readable
public classLineNumberReaderextendsBufferedReader
A buffered character-input stream that keeps track of line numbers. This class defines methodssetLineNumber(int) andgetLineNumber() for setting and getting the current line number respectively.

By default, line numbering begins at 0. This number increments at everyline terminator as the data is read, and at the end of the stream if the last character in the stream is not a line terminator. This number can be changed with a call tosetLineNumber(int). Note however, thatsetLineNumber(int) does not actually change the current position in the stream; it only changes the value that will be returned bygetLineNumber().

A line is considered to beterminated by any one of a line feed ('\n'), a carriage return ('\r'), or a carriage return followed immediately by a linefeed, or any of the previous terminators followed by end of stream, or end of stream not preceded by another terminator.

Since:
1.1

  • Constructor Details

    • 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 Details

    • setLineNumber

      public void setLineNumber(int lineNumber)
      Set the current line number.
      Parameters:
      lineNumber - An int specifying the line number
      See Also:

    • getLineNumber

      public int getLineNumber()
      Get the current line number.
      Returns:
      The current line number
      See Also:

    • read

      public int read() throwsIOException
      Read a single character.Line terminators are compressed into single newline ('\n') characters. The current line number is incremented whenever a line terminator is read, or when the end of the stream is reached and the last character in the stream is not a line terminator.
      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) throwsIOException
      Reads characters into a portion of an array. This method will block until some input is available, an I/O error occurs, or the end of the stream is reached.

      Iflen is zero, then no characters are read and0 is returned; otherwise, there is an attempt to read at least one character. If no character is available because the stream is at its end, the value-1 is returned; otherwise, at least one character is read and stored intocbuf.

      Line terminators are compressed into single newline ('\n') characters. The current line number is incremented whenever a line terminator is read, or when the end of the stream is reached and the last character in the stream is not a line terminator.

      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 characters read, or -1 if the end of the stream has been reached
      Throws:
      IndexOutOfBoundsException - Ifoff is negative, orlen is negative, orlen is greater thancbuf.length - off
      IOException - If an I/O error occurs

    • readLine

      public String readLine() throwsIOException
      Read a line of text.Line terminators are compressed into single newline ('\n') characters. The current line number is incremented whenever a line terminator is read, or when the end of the stream is reached and the last character in the stream is not a line terminator.
      Overrides:
      readLine in class BufferedReader
      Returns:
      A String containing the contents of the line, not including anyline termination characters, ornull if the end of the stream has been reached
      Throws:
      IOException - If an I/O error occurs
      See Also:

    • mark

      public void mark(int readAheadLimit) throwsIOException
      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() throwsIOException
      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