LineNumberReader
@Deprecated public class LineNumberInputStream extends FilterInputStream
InputStream
and counts the line terminators
encountered while reading the data. Line numbering starts at 0. Recognized
line terminator sequences are '\r'
, '\n'
and "\r\n"
.
When using read
, line terminator sequences are always translated into
'\n'
.in
Constructor and Description |
---|
LineNumberInputStream(InputStream in)
Deprecated.
|
Modifier and Type | Method and Description |
---|---|
int |
available()
Deprecated.
Returns an estimated number of bytes that can be read or skipped without blocking for more
input.
|
int |
getLineNumber()
Deprecated.
Returns the current line number for this stream.
|
void |
mark(int readlimit)
Deprecated.
Sets a mark position in this stream.
|
int |
read()
Deprecated.
Reads a single byte from the filtered stream and returns it as an integer
in the range from 0 to 255.
|
int |
read(byte[] buffer,
int offset,
int length)
Deprecated.
Reads at most
length bytes from the filtered stream and stores
them in the byte array buffer starting at offset . |
void |
reset()
Deprecated.
Resets this stream to the last marked location.
|
void |
setLineNumber(int lineNumber)
Deprecated.
Sets the line number of this stream to the specified
lineNumber . |
long |
skip(long byteCount)
Deprecated.
Skips
count number of bytes in this stream. |
close, markSupported
read
public LineNumberInputStream(InputStream in)
LineNumberInputStream
on the InputStream
in
. Line numbers are counted for all data read from this stream.
Warning: passing a null source creates an invalid
LineNumberInputStream
. All operations on such a stream will fail.
in
- The non-null input stream to count line numbers.public int available() throws IOException
Note that this method provides such a weak guarantee that it is not very useful in practice.
Firstly, the guarantee is "without blocking for more input" rather than "without blocking": a read may still block waiting for I/O to complete — the guarantee is merely that it won't have to wait indefinitely for data to be written. The result of this method should not be used as a license to do I/O on a thread that shouldn't be blocked.
Secondly, the result is a conservative estimate and may be significantly smaller than the actual number of bytes available. In particular, an implementation that always returns 0 would be correct. In general, callers should only use this method if they'd be satisfied with treating the result as a boolean yes or no answer to the question "is there definitely data ready?".
Thirdly, the fact that a given number of bytes is "available" does not guarantee that a read or skip will actually read or skip that many bytes: they may read or skip fewer.
It is particularly important to realize that you must not use this method to
size a container and assume that you can read the entirety of the stream without needing
to resize the container. Such callers should probably write everything they read to a
ByteArrayOutputStream
and convert that to a byte array. Alternatively, if you're
reading from a file, File.length()
returns the current length of the file (though
assuming the file's length can't change may be incorrect, reading a file is inherently
racy).
The default implementation of this method in InputStream
always returns 0.
Subclasses should override this method if they are able to indicate the number of bytes
available.
Note that the source stream may just be a sequence of "\r\n"
bytes
which are converted into '\n'
by this stream. Therefore,
available
returns only in.available() / 2
bytes as
result.
available
in class FilterInputStream
IOException
- if this stream is closed or an error occurspublic int getLineNumber()
public void mark(int readlimit)
readlimit
indicates how many bytes can be read before the mark is invalidated.
Sending reset()
will reposition this stream back to the marked
position, provided that readlimit
has not been surpassed.
The line number count will also be reset to the last marked
line number count.
This implementation sets a mark in the filtered stream.
mark
in class FilterInputStream
readlimit
- the number of bytes that can be read from this stream before
the mark is invalidated.FilterInputStream.markSupported()
,
reset()
public int read() throws IOException
The line number count is incremented if a line terminator is encountered.
Recognized line terminator sequences are '\r'
, '\n'
and
"\r\n"
. Line terminator sequences are always translated into
'\n'
.
read
in class FilterInputStream
IOException
- if the stream is closed or another IOException occurs.public int read(byte[] buffer, int offset, int length) throws IOException
length
bytes from the filtered stream and stores
them in the byte array buffer
starting at offset
.
Returns the number of bytes actually read or -1 if no bytes have been
read and the end of this stream has been reached.
The line number count is incremented if a line terminator is encountered.
Recognized line terminator sequences are '\r'
, '\n'
and
"\r\n"
. Line terminator sequences are always translated into
'\n'
.
read
in class FilterInputStream
buffer
- the array in which to store the bytes read.offset
- the initial position in buffer
to store the bytes read
from this stream.length
- the maximum number of bytes to store in buffer
.IndexOutOfBoundsException
- if offset < 0
or length < 0
, or if
offset + length
is greater than the length of
buffer
.IOException
- if this stream is closed or another IOException occurs.NullPointerException
- if buffer
is null
.public void reset() throws IOException
reset
in class FilterInputStream
IOException
- if this stream is already closed, no mark has been set or the
mark is no longer valid because more than readlimit
bytes have been read since setting the mark.mark(int)
,
FilterInputStream.markSupported()
public void setLineNumber(int lineNumber)
lineNumber
. Note that this may have side effects on the
line number associated with the last marked position.public long skip(long byteCount) throws IOException
count
number of bytes in this stream. Subsequent
calls to read
will not return these bytes unless reset
is
used. This implementation skips byteCount
bytes in the
filtered stream and increments the line number count whenever line
terminator sequences are skipped.skip
in class FilterInputStream
byteCount
- the number of bytes to skip.IOException
- if this stream is closed or another IOException occurs.mark(int)
,
read()
,
reset()