Class LineNumberReader
- All Implemented Interfaces:
Closeable
,AutoCloseable
,Readable
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 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 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, or any of the previous terminators followed by end of stream, or end of stream not preceded by another terminator.
- Since:
- 1.1
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Field Summary
-
Constructor Summary
ConstructorDescriptionCreate 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
Modifier and TypeMethodDescriptionint
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) Reads characters into a portion of an array.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.Methods declared in class java.io.BufferedReader
close, lines, markSupported, ready
Methods declared in class java.io.Reader
nullReader, read, read, skip, transferTo
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Constructor Details
-
LineNumberReader
Create a new line-numbering reader, using the default input-buffer size.- Parameters:
in
- A Reader object to provide the underlying stream
-
LineNumberReader
Create a new line-numbering reader, reading characters into a buffer of the given size.- Parameters:
in
- A Reader object to provide the underlying streamsz
- 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
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 classBufferedReader
- Returns:
- The character read, or -1 if the end of the stream has been reached
- Throws:
IOException
- If an I/O error occurs
-
read
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.If
len
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 classBufferedReader
- Parameters:
cbuf
- Destination bufferoff
- Offset at which to start storing characterslen
- 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
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 classBufferedReader
- 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- See Also:
-
mark
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 classBufferedReader
- 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
Reset the stream to the most recent mark.- Overrides:
reset
in classBufferedReader
- Throws:
IOException
- If the stream has not been marked, or if the mark has been invalidated
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