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.
Field Detail |
private boolean skipLF
private boolean markedSkipLF
Constructor Detail |
public BufferedReader(Reader in, int sz)
in
- A Readersz
- Input-buffer sizeIllegalArgumentException
- If sz is <= 0
public BufferedReader(Reader in)
in
- A ReaderMethod Detail |
private void ensureOpen()
private void fill()
public int read()
IOException
- If an I/O error occursprivate int read1(char[] cbuf, int off, int len)
public int read(char[] cbuf, int off, int len)
This method implements the general contract of the corresponding {@link Reader#read(char[], int, int) read}
method of the {@link 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, or ready
method of the underlying stream returns false
, indicating that further input requests would block. 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.
cbuf
- Destination bufferoff
- Offset at which to start storing characterslen
- Maximum number of characters to readIOException
- If an I/O error occursString readLine(boolean ignoreLF)
ignoreLF
- If true, the next '\n' will be skippedIOException
- If an I/O error occurspublic String readLine()
IOException
- If an I/O error occurspublic long skip(long n)
n
- The number of characters to skipIllegalArgumentException
- If n
is negative.IOException
- If an I/O error occurspublic boolean ready()
IOException
- If an I/O error occurspublic boolean markSupported()
public void mark(int readAheadLimit)
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.IllegalArgumentException
- If readAheadLimit is < 0
* @exception IOException If an I/O error occurs
public void reset()
IOException
- If the stream has never been marked, or if the mark has been invalidatedpublic void close()
IOException
- If an I/O error occurs