Closeable
, AutoCloseable
, Readable
LineNumberReader
Reads 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.
Constructors
Creates a buffering character-input stream that uses a default-sized input buffer.
Creates a buffering character-input stream that uses an input buffer of the specified size.
void
Closes the stream and releases any system resources associated with it.
Returns a Stream
, the elements of which are lines read from this BufferedReader
.
void
Marks the present position in the stream.
boolean
Tells whether this stream supports the mark() operation, which it does.
int
Reads a single character.
int
read(char[] cbuf, int off, int len)
Reads characters into a portion of an array.
boolean
Tells whether this stream is ready to be read.
void
Resets the stream to the most recent mark.
Methods declared in class java.lang.Objectclone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Creates a buffering character-input stream that uses an input buffer of the specified size.
in
- A Reader
sz
- Input-buffer size
IllegalArgumentException
- If sz <= 0
Creates a buffering character-input stream that uses a default-sized input buffer.
in
- A Reader
Reads a single character.
read
in class Reader
0x00-0xffff
), or -1 if the end of the stream has been reached
IOException
- If an I/O error occurs
throws
IOExceptionReads characters into a portion of an array.
This method implements the general contract of the corresponding read
method of the Reader
class. As an additional convenience, it attempts to read as many characters as possible by repeatedly invoking the read
method of the underlying stream. This iterated read
continues until one of the following conditions becomes true:
read
method of the underlying stream returns -1
, indicating end-of-file, orready
method of the underlying stream returns false
, indicating that further input requests would block.If the first
read
on the underlying stream returns
-1
to indicate end-of-file then this method returns
-1
. Otherwise this method returns the number of characters actually read.
Subclasses of this class are encouraged, but not required, to attempt to read as many characters as possible in the same fashion.
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 BufferedReader
s will not copy data unnecessarily.
read
in class Reader
cbuf
- Destination buffer
off
- Offset at which to start storing characters
len
- Maximum number of characters to read
IndexOutOfBoundsException
- If off
is negative, or len
is negative, or len
is greater than cbuf.length - off
IOException
- If an I/O error occurs
Reads a line of text. A line is considered to be terminated by any one of a line feed ('\n'), a carriage return ('\r'), a carriage return followed immediately by a line feed, or by reaching the end-of-file (EOF).
IOException
- If an I/O error occurs
Tells 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.
ready
in class Reader
IOException
- If an I/O error occurs
public boolean markSupported()
Tells whether this stream supports the mark() operation, which it does.
markSupported
in class Reader
throws
IOExceptionMarks the present position in the stream. Subsequent calls to reset() will attempt to reposition the stream to this point.
mark
in class Reader
readAheadLimit
- Limit on the number of characters that may be read while still preserving the mark. An attempt to reset the stream after reading characters up to this limit or beyond 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.
IllegalArgumentException
- If readAheadLimit < 0
IOException
- If an I/O error occurs
Resets the stream to the most recent mark.
reset
in class Reader
IOException
- If the stream has never been marked, or if the mark has been invalidated
Reader
Closes the stream and releases any system resources associated with it. Once the stream has been closed, further read(), ready(), mark(), reset(), or skip() invocations will throw an IOException. Closing a previously closed stream has no effect.
close
in interface AutoCloseable
close
in interface Closeable
close
in class Reader
IOException
- If an I/O error occurs
Returns a
Stream
, the elements of which are lines read from this
BufferedReader
. The
Stream
is lazily populated, i.e., read only occurs during the
terminal stream operation.
The reader must not be operated on during the execution of the terminal stream operation. Otherwise, the result of the terminal stream operation is undefined.
After execution of the terminal stream operation there are no guarantees that the reader will be at a specific position from which to read the next character or line.
If an IOException
is thrown when accessing the underlying BufferedReader
, it is wrapped in an UncheckedIOException
which will be thrown from the Stream
method that caused the read to take place. This method will return a Stream if invoked on a BufferedReader that is closed. Any operation on that stream that requires reading from the BufferedReader after it is closed, will cause an UncheckedIOException to be thrown.
Stream<String>
providing the lines of text described by this BufferedReader
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