java.io

Class LineNumberInputStream

Implemented Interfaces:
Closeable

public class LineNumberInputStream
extends FilterInputStream

This class is an input stream filter that provides the added functionality of keeping track of the current line number.

A line is a sequence of bytes ending with a carriage return character ('\r'), a newline character ('\n'), or a carriage return character followed immediately by a linefeed character. In all three cases, the line terminating character(s) are returned as a single newline character.

The line number begins at 0, and is incremented by 1 when a read returns a newline character.

Since:
JDK1.0
See Also:
LineNumberReader

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

LineNumberInputStream(InputStream in)
Constructs a newline number input stream that reads its input from the specified input stream.

Method Summary

int
available()
Returns the number of bytes that can be read from this input stream without blocking.
int
getLineNumber()
Returns the current line number.
void
mark(int readlimit)
Marks the current position in this input stream.
int
read()
Reads the next byte of data from this input stream.
int
read(b[] , int off, int len)
Reads up to len bytes of data from this input stream into an array of bytes.
void
reset()
Repositions this stream to the position at the time the mark method was last called on this input stream.
void
setLineNumber(int lineNumber)
Sets the line number to the specified argument.
long
skip(long n)
Skips over and discards n bytes of data from this input stream.

Methods inherited from class java.io.FilterInputStream

available, close, mark, markSupported, read, read, read, reset, skip

Methods inherited from class java.io.InputStream

available, close, mark, markSupported, read, read, read, reset, skip

Methods inherited from class java.lang.Object

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

Constructor Details

LineNumberInputStream

public LineNumberInputStream(InputStream in)
Constructs a newline number input stream that reads its input from the specified input stream.
Parameters:
in - the underlying input stream.
Usages and Demos :

View More Examples of LineNumberInputStream(InputStream in)
   1:     SequenceInputStream sis = new SequenceInputStream( sbis, fis );
   2:     LineNumberInputStream lsis = new LineNumberInputStream( sis );
   3: 
   4:     System.out.print( "0: " );

View Full Code Here
   1:                           bis = new BufferedInputStream(fis);
   2:                           lnis = new LineNumberInputStream(bis);
   3:                           dis = new DataInputStream(lnis);
   4:                           while((strLine=dis.readLine())!=null)
   5:                           {

View Full Code Here
   1:       StringBufferInputStream sbis = new StringBufferInputStream(str);
   2:       LineNumberInputStream lnis = new LineNumberInputStream(sbis);
   3: 
   4:         ...
   5:       StringBufferInputStream sbis = new StringBufferInputStream(str);
   6:       LineNumberInputStream lnis = new LineNumberInputStream(sbis);
   7: 
   8:       byte[] buf = new byte[32];
   9:       int bytes_read; 

View Full Code Here

Method Details

available

public int available()
            throws IOException
Returns the number of bytes that can be read from this input stream without blocking.

Note that if the underlying input stream is able to supply k input characters without blocking, the LineNumberInputStream can guarantee only to provide k/2 characters without blocking, because the k characters from the underlying input stream might consist of k/2 pairs of '\r' and '\n', which are converted to just k/2 '\n' characters.

Overrides:
available in interface FilterInputStream
Returns:
the number of bytes that can be read from this input stream without blocking.
Throws:
IOException - if an I/O error occurs.

getLineNumber

public int getLineNumber()
Returns the current line number.
Returns:
the current line number.
Usages and Demos :

View More Examples of getLineNumber()
   1:                   BufferedInputStream bis;
   2:                   LineNumberInputStream lnis;
   3:                   String strLine;
   4:         ...
   5:                           bis = new BufferedInputStream(fis);
   6:                           lnis = new LineNumberInputStream(bis);
   7:                           dis = new DataInputStream(lnis);
   8:         ...
   9:                           {
  10:                                   int nLineNumber = lnis.getLineNumber();
  11:                                   System.out.println(nLineNumber+":"+strLine);

View Full Code Here
   1: {
   2:   System.out.println("Started test of LineNumberInputStream");
   3: 
   4:         ...
   5:       StringBufferInputStream sbis = new StringBufferInputStream(str);
   6:       LineNumberInputStream lnis = new LineNumberInputStream(sbis);
   7: 
   8:         ...
   9: 
  10:       if (lnis.getLineNumber() != 6)
  11:         {
  12:         ...
  13:           System.out.println("Line number was wrong.  Expected 6 but got " +
  14:             lnis.getLineNumber());

View Full Code Here

mark

public void mark(int readlimit)
Marks the current position in this input stream. A subsequent call to the reset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes.

The mark method of LineNumberInputStream remembers the current line number in a private variable, and then calls the mark method of the underlying input stream.

Overrides:
mark in interface FilterInputStream
Parameters:
readlimit - the maximum limit of bytes that can be read before the mark position becomes invalid.

read

public int read()
            throws IOException
Reads the next byte of data from this input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

The read method of LineNumberInputStream calls the read method of the underlying input stream. It checks for carriage returns and newline characters in the input, and modifies the current line number as appropriate. A carriage-return character or a carriage return followed by a newline character are both converted into a single newline character.

Overrides:
read in interface FilterInputStream
Returns:
the next byte of data, or -1 if the end of this stream is reached.
Throws:
IOException - if an I/O error occurs.
Usages and Demos :

View More Examples of read()
   1:     File file = null ;
   2:     LineNumberInputStream in = null ;
   3:     int         ch = -1 ;
   4:         ...
   5:         append (Character.toLowerCase((char)ch)) ;
   6:         ch = in.read() ;
   7:     }
   8:         ...
   9:         append (ch) ;
  10:         ch = in.read() ;
  11:     }
  12:         ...
  13:           case ' ': case '\t': case '\n':
  14:               ch = in.read() ;

View Full Code Here

read

public int read(b[] ,
                int off,
                int len)
            throws IOException
Reads up to len bytes of data from this input stream into an array of bytes. This method blocks until some input is available.

The read method of LineNumberInputStream repeatedly calls the read method of zero arguments to fill in the byte array.

Overrides:
read in interface FilterInputStream
Parameters:
off - the start offset of the data.
len - the maximum number of bytes read.
Returns:
the total number of bytes read into the buffer, or -1 if there is no more data because the end of this stream has been reached.
Throws:
IOException - if an I/O error occurs.
See Also:
read()

reset

public void reset()
            throws IOException
Repositions this stream to the position at the time the mark method was last called on this input stream.

The reset method of LineNumberInputStream resets the line number to be the line number at the time the mark method was called, and then calls the reset method of the underlying input stream.

Stream marks are intended to be used in situations where you need to read ahead a little to see what's in the stream. Often this is most easily done by invoking some general parser. If the stream is of the type handled by the parser, it just chugs along happily. If the stream is not of that type, the parser should toss an exception when it fails, which, if it happens within readlimit bytes, allows the outer code to reset the stream and try another parser.

Overrides:
reset in interface FilterInputStream
Throws:
IOException - if an I/O error occurs.

setLineNumber

public void setLineNumber(int lineNumber)
Sets the line number to the specified argument.
Parameters:
lineNumber - the new line number.
Usages and Demos :

View More Examples of setLineNumber(int lineNumber)
   1: {
   2:   System.out.println("Started test of LineNumberInputStream");
   3: 
   4:         ...
   5:       StringBufferInputStream sbis = new StringBufferInputStream(str);
   6:       LineNumberInputStream lnis = new LineNumberInputStream(sbis);
   7: 
   8:         ...
   9:       lnis.setLineNumber(2);

View Full Code Here

skip

public long skip(long n)
            throws IOException
Skips over and discards n bytes of data from this input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. The actual number of bytes skipped is returned. If n is negative, no bytes are skipped.

The skip method of LineNumberInputStream creates a byte array and then repeatedly reads into it until n bytes have been read or the end of the stream has been reached.

Overrides:
skip in interface FilterInputStream
Parameters:
n - the number of bytes to be skipped.
Returns:
the actual number of bytes skipped.
Throws:
IOException - if an I/O error occurs.