java.lang.Object | |||
↳ | java.io.InputStream | ||
↳ | java.io.FilterInputStream | ||
↳ | java.io.LineNumberInputStream |
This class is deprecated.
This class incorrectly assumes that bytes adequately represent
characters. As of JDK 1.1, the preferred way to operate on
character streams is via the new character-stream classes, which
include a class for counting line numbers.
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.
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Inherited Fields | |||||||||||
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From class
java.io.FilterInputStream
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Public Constructors | |||||||||||
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Constructs a newline number input stream that reads its input
from the specified input stream.
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Public Methods | |||||||||||
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Returns the number of bytes that can be read from this input
stream without blocking.
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Returns the current line number.
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Marks the current position in this input stream.
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Reads the next byte of data from this input stream.
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Reads up to
len bytes of data from this input stream
into an array of bytes. | |||||||||||
Repositions this stream to the position at the time the
mark method was last called on this input stream. | |||||||||||
Sets the line number to the specified argument.
| |||||||||||
Skips over and discards
n bytes of data from this
input stream. |
[Expand]
Inherited Methods | |||||||||||
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From class
java.io.FilterInputStream
| |||||||||||
From class
java.io.InputStream
| |||||||||||
From class
java.lang.Object
| |||||||||||
From interface
java.io.Closeable
|
Constructs a newline number input stream that reads its input from the specified input stream.
in | the underlying input stream. |
---|
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.
IOException | if an I/O error occurs. |
---|
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.
readlimit | the maximum limit of bytes that can be read before the mark position becomes invalid. |
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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.
-1
if the end of this
stream is reached.IOException | if an I/O error occurs. |
---|
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.
b | the buffer into which the data is read. |
---|---|
off | the start offset of the data. |
len | the maximum number of bytes read. |
-1
if there is no more data because the end of
this stream has been reached.IOException | if an I/O error occurs. |
---|
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.
IOException | if an I/O error occurs. |
---|
Sets the line number to the specified argument.
lineNumber | the new line number. |
---|
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.
n | the number of bytes to be skipped. |
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IOException | if an I/O error occurs. |
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