Class LineNumberReader
- java.lang.Object
-
- java.io.Reader
-
- java.io.BufferedReader
-
- java.io.LineNumberReader
- All Implemented Interfaces:
-
Closeable
,AutoCloseable
,Readable
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:
- 1.1
Field Summary
Fields declared in class java.io.Reader
lock
Constructor Summary
Constructor | Description |
---|---|
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
Modifier and Type | Method | Description |
---|---|---|
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 declared in class java.io.BufferedReader
lines, markSupported, ready
Methods declared in class java.io.Reader
close, nullReader, read, read, transferTo
Methods declared in 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. Whenever a line terminator is read the current line number is incremented.
- 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
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 classBufferedReader
- 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 -
IndexOutOfBoundsException
- If an I/O error occurs
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 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:
Files.readAllLines(java.nio.file.Path, java.nio.charset.Charset)
skip
public long skip(long n) throws IOException
Skip characters.
- Overrides:
-
skip
in classBufferedReader
- Parameters:
-
n
- The number of characters to skip - Returns:
- The number of characters actually skipped
- Throws:
-
IOException
- If an I/O error occurs -
IllegalArgumentException
- Ifn
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 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
public void reset() throws IOException
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