Read text from a character-input stream, buffering characters so as to
provide for the efficient reading of characters, arrays, and lines.
The buffer size may be specified, or the default size may be used. The
default is large enough for most purposes.
In general, each read request made of a Reader causes a corresponding
read request to be made of the underlying character or byte stream. It is
therefore advisable to wrap a BufferedReader around any Reader whose read()
operations may be costly, such as FileReaders and InputStreamReaders. For
example,
BufferedReader in
= new BufferedReader(new FileReader("foo.in"));
will buffer the input from the specified file. Without buffering, each
invocation of read() or readLine() could cause bytes to be read from the
file, converted into characters, and then returned, which can be very
inefficient.
Programs that use DataInputStreams for textual input can be localized by
replacing each DataInputStream with an appropriate BufferedReader.
read
public int read(char cbuf[],
int off,
int len) throws IOException
Read characters into a portion of an array.
Ordinarily this method takes characters from this stream's character
buffer, filling it from the underlying stream as necessary. If,
however, the buffer is empty, the mark is not valid, and the requested
length is at least as large as the buffer, then this method will read
characters directly from the underlying stream into the given array.
Thus redundant BufferedReaders will not copy data
unnecessarily.
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
been reached
Read a line of text. 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.
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
Tell whether this stream is ready to be read. A buffered character
stream is ready if the buffer is not empty, or if the underlying
character stream is ready.
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.
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. A limit value larger
than the size of the input buffer will cause a
new buffer to be allocated whose size is no
smaller than limit. Therefore large values
should be used with care.
BufferedReader(Reader)
close()
BufferedReader
read