Class LineNumberInputStream

public LineNumberInputStream(InputStream in)

Create a new LineNumberInputStream that reads from the specified subordinate InputStream

Parameters:

in - The subordinate InputStream to read from

public int available()
            throws IOException

This method returns the number of bytes that can be read from the stream before the stream can block. This method is tricky because the subordinate InputStream might return only "\r\n" characters, which are replaced by a single "\n" character by the read() method of this class. So this method can only guarantee that in.available() / 2 bytes can actually be read before blocking. In practice, considerably more bytes might be read before blocking

Note that the stream may not block if additional bytes beyond the count returned by this method are read.

Overrides:

available in interface FilterInputStream

Returns:

The number of bytes that can be read before blocking could occur

Throws:

IOException - If an error occurs

public int getLineNumber()

This method returns the current line number

Returns:

The current line number

public void mark(int readlimit)

This method marks a position in the input to which the stream can be "reset" byte calling the reset() method. The parameter readlimit is the number of bytes that can be read from the stream after setting the mark before the mark becomes invalid. For example, if mark() is called with a read limit of 10, then when 11 bytes of data are read from the stream before the reset() method is called, then the mark is invalid and the stream object instance is not required to remember the mark.

In this class, this method will remember the current line number as well as the current position in the stream. When the reset() method is called, the line number will be restored to the saved line number in addition to the stream position.

This method only works if the subordinate stream supports mark/reset functionality.

Overrides:

mark in interface FilterInputStream

Parameters:

readlimit - The number of bytes that can be read before the mark becomes invalid

public int read()
            throws IOException

This method reads an unsigned byte from the input stream and returns it as an int in the range of 0-255. This method will return -1 if the end of the stream has been reached.

Note that if a line termination sequence is encountered (ie, "\r", "\n", or "\r\n") then that line termination sequence is converted to a single "\n" value which is returned from this method. This means that it is possible this method reads two bytes from the subordinate stream instead of just one.

Note that this method will block until a byte of data is available to be read.

Overrides:

read in interface FilterInputStream

Returns:

The byte read or -1 if end of stream

Throws:

IOException - If an error occurs

public int read(byte[] b,
                int off,
                int len)
            throws IOException

This method reads bytes from a stream and stores them into a caller supplied buffer. It starts storing data at index offset into the buffer and attemps to read len bytes. This method can return before reading the number of bytes requested. The actual number of bytes read is returned as an int. A -1 is returned to indicated the end of the stream.

This method will block until some data can be read.

Note that if a line termination sequence is encountered (ie, "\r", "\n", or "\r\n") then that line termination sequence is converted to a single "\n" value which is stored in the buffer. Only a single byte is counted towards the number of bytes read in this case.

Overrides:

read in interface FilterInputStream

Parameters:

b - The array into which the bytes read should be stored

off - The offset into the array to start storing bytes

len - The requested number of bytes to read

Returns:

The actual number of bytes read, or -1 if end of stream

Throws:

IOException - If an error occurs.

public void reset()
            throws IOException

This method resets a stream to the point where the mark() method was called. Any bytes that were read after the mark point was set will be re-read during subsequent reads.

In this class, this method will also restore the line number that was current when the mark() method was called.

This method only works if the subordinate stream supports mark/reset functionality.

Overrides:

reset in interface FilterInputStream

Throws:

IOException - If an error occurs

public void setLineNumber(int lineNumber)

This method sets the current line number to the specified value.

Parameters:

lineNumber - The new line number

public long skip(long n)
            throws IOException

This method skips up to the requested number of bytes in the input stream. The actual number of bytes skipped is returned. If the desired number of bytes to skip is negative, no bytes are skipped.

Overrides:

skip in interface FilterInputStream

Parameters:

n - requested number of bytes to skip.

Returns:

The actual number of bytes skipped.

Throws:

IOException - If an error occurs.