public class BufferedReader extends Reader
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.
FileReader, InputStreamReader, Files.newBufferedReader(java.nio.file.Path, java.nio.charset.Charset)
lock public BufferedReader(Reader in,
int sz) Creates a buffering character-input stream that uses an input buffer of the specified size.
in - A Readersz - Input-buffer sizeIllegalArgumentException - If sz <= 0
public BufferedReader(Reader in)
Creates a buffering character-input stream that uses a default-sized input buffer.
in - A Readerpublic int read()
throws IOException Reads a single character.
read in class Reader
0x00-0xffff), or -1 if the end of the stream has been reachedIOException - If an I/O error occurspublic int read(char[] cbuf,
int off,
int len)
throws IOException Reads characters into a portion of an array.
This method implements the general contract of the corresponding readReaderread 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 BufferedReaders will not copy data unnecessarily.
read in class Reader
cbuf - Destination bufferoff - Offset at which to start storing characterslen - Maximum number of characters to readIOException - If an I/O error occurspublic String readLine()
throws IOException Reads 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.
IOException - If an I/O error occursFiles.readAllLines(java.nio.file.Path, java.nio.charset.Charset)public long skip(long n)
throws IOException Skips characters.
skip in class Reader
n - The number of characters to skipIllegalArgumentException - If n is negative.IOException - If an I/O error occurspublic boolean ready()
throws IOException 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 occurspublic boolean markSupported()
Tells whether this stream supports the mark() operation, which it does.
markSupported in class Reader
public void mark(int readAheadLimit)
throws IOException Marks 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 occurspublic void reset()
throws IOException 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 invalidatedpublic void close()
throws IOException Description copied from class: 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 Closeable
close in interface AutoCloseable
close in class Reader
IOException - If an I/O error occurspublic Stream<String> lines()
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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Documentation extracted from Debian's OpenJDK Development Kit package.
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