OpenJDK 27 · java.io.BufferedReader · APIdia, the JavaDoc alternative

Modifier and Type	Field and Description
private char[]	cb
private static final int	DEFAULT_CHAR_BUFFER_SIZE
private static final int	DEFAULT_EXPECTED_LINE_LENGTH
private Reader	in
private static final int	INVALIDATED
private int	markedChar
private boolean	markedSkipLF The skipLF flag when the mark was set
private int	nChars
private int	nextChar
private int	readAheadLimit
private boolean	skipLF If the next character is a line feed, skip it
private static final int	UNMARKED

Access	Constructor and Description
public	BufferedReader(Reader A Reader in, int Input-buffer size sz) Creates a buffering character-input stream that uses an input buffer of the specified size.
public	BufferedReader(Reader A Reader in) Creates a buffering character-input stream that uses a default-sized input buffer.

Method Summary

Modifier and Type	Method and Description
public void	close() Implements abstract java.io.Reader.close. Implements java.io.Closeable.close. Closes the stream and releases any system resources associated with it.
private void	ensureOpen() Checks to make sure that the stream has not been closed
private void	fill() Fills the input buffer, taking the mark into account if it is valid.
public Stream<String>	Returns: a `Stream<String>` providing the lines of text described by this `BufferedReader` lines() Returns a `Stream`, the elements of which are lines read from this `BufferedReader`.
public void	mark(int 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. readAheadLimit) Overrides java.io.Reader.mark. Marks the present position in the stream.
public boolean	markSupported() Overrides java.io.Reader.markSupported. Tells whether this stream supports the mark() operation, which it does.
public int	Returns: The character read, as an integer in the range 0 to 65535 (`0x00-0xffff`), or -1 if the end of the stream has been reached read() Overrides java.io.Reader.read. Reads a single character.
public int	read(char[] cbuf, int off, int len) Implements abstract java.io.Reader.read. Reads characters into a portion of an array.
private int	read1(char[] cbuf, int off, int len) Reads characters into a portion of an array, reading from the underlying stream if necessary.
pack-priv String	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 without reading any characters readLine(boolean If true, the next '\n' will be skipped ignoreLF, boolean[] Output: Whether a line terminator was encountered while reading the line; may be `null`. term) Reads a line of text.
public String	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 without reading any characters readLine() Reads a line of text.
public boolean	ready() Overrides java.io.Reader.ready. Tells whether this stream is ready to be read.
public void	reset() Overrides java.io.Reader.reset. Resets the stream to the most recent mark.
public long	skip(long n) Overrides java.io.Reader.skip. Skips characters.

Inherited from java.io.Reader:: nullReader of read read readAllAsString readAllLines transferTo

cb	back to summary
private char[] cb

DEFAULT_CHAR_BUFFER_SIZE	back to summary
private static final int DEFAULT_CHAR_BUFFER_SIZE

DEFAULT_EXPECTED_LINE_LENGTH	back to summary
private static final int DEFAULT_EXPECTED_LINE_LENGTH

in	back to summary
private Reader in

INVALIDATED	back to summary
private static final int INVALIDATED

markedChar	back to summary
private int markedChar

markedSkipLF	back to summary
private boolean markedSkipLF The skipLF flag when the mark was set

nChars	back to summary
private int nChars

nextChar	back to summary
private int nextChar

readAheadLimit	back to summary
private int readAheadLimit

skipLF	back to summary
private boolean skipLF If the next character is a line feed, skip it

UNMARKED	back to summary
private static final int UNMARKED

BufferedReader	back to summary
public BufferedReader(Reader in, int sz) Creates a buffering character-input stream that uses an input buffer of the specified size. Parameters in:Reader A Reader sz:int Input-buffer size Exceptions IllegalArgumentException: If `sz <= 0`

BufferedReader	back to summary
public BufferedReader(Reader in) Creates a buffering character-input stream that uses a default-sized input buffer. Parameters in:Reader A Reader

Method Detail

close	back to summary
public void close() throws IOException Implements abstract java.io.Reader.close. Implements java.io.Closeable.close. Doc from java.io.Reader.close. 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. Exceptions IOException: If an I/O error occurs

back to summary

public void close() throws IOException

Implements abstract java.io.Reader.close.

Implements java.io.Closeable.close.

Doc from java.io.Reader.close.

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.

Exceptions

IOException:: If an I/O error occurs

ensureOpen	back to summary
private void ensureOpen() throws IOException Checks to make sure that the stream has not been closed

fill	back to summary
private void fill() throws IOException Fills the input buffer, taking the mark into account if it is valid.

lines back to summary

lines	back to summary
public 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. Returns:Stream<String> a `Stream<String>` providing the lines of text described by this `BufferedReader` Since 1.8

public 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.

Returns:Stream<String>: a Stream<String> providing the lines of text described by this BufferedReader
Since: 1.8

mark back to summary

mark	back to summary
public void mark(int readAheadLimit) throws IOException Overrides java.io.Reader.mark. Marks the present position in the stream. Subsequent calls to reset() will attempt to reposition the stream to this point. Parameters readAheadLimit:int 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. Exceptions IOException: If an I/O error occurs IllegalArgumentException: If `readAheadLimit < 0`

public void mark(int readAheadLimit) throws IOException

Overrides java.io.Reader.mark.

Marks the present position in the stream. Subsequent calls to reset() will attempt to reposition the stream to this point.

Parameters

readAheadLimit:int: 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.

Exceptions

IOException:: If an I/O error occurs
IllegalArgumentException:: If readAheadLimit < 0

markSupported	back to summary
public boolean markSupported() Overrides java.io.Reader.markSupported. Tells whether this stream supports the mark() operation, which it does.

markSupported

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public boolean markSupported()

Overrides java.io.Reader.markSupported.

Tells whether this stream supports the mark() operation, which it does.

read back to summary

read	back to summary
public int read() throws IOException Overrides java.io.Reader.read. Reads a single character. Returns:int The character read, as an integer in the range 0 to 65535 (`0x00-0xffff`), or -1 if the end of the stream has been reached Exceptions IOException: If an I/O error occurs

public int read() throws IOException

Overrides java.io.Reader.read.

Reads a single character.

Returns:int

The character read, as an integer in the range 0 to 65535 (0x00-0xffff), or -1 if the end of the stream has been reached

Exceptions

IOException:: If an I/O error occurs

read back to summary

read	back to summary
public int read(char[] cbuf, int off, int len) throws IOException Implements abstract java.io.Reader.read. Reads 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: The specified number of characters have been read, The `read` method of the underlying stream returns `-1`, indicating end-of-file, or The `ready` 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. Exceptions IOException: If an I/O error occurs IndexOutOfBoundsException: If `off` is negative, or `len` is negative, or `len` is greater than `cbuf.length - off`

public int read(char[] cbuf, int off, int len) throws IOException

Implements abstract java.io.Reader.read.

Reads 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:

The specified number of characters have been read,
The read method of the underlying stream returns -1, indicating end-of-file, or
The ready 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 BufferedReaders will not copy data unnecessarily.

Exceptions

IOException:: If an I/O error occurs
IndexOutOfBoundsException:: If off is negative, or len is negative, or len is greater than cbuf.length - off

read1	back to summary
private int read1(char[] cbuf, int off, int len) throws IOException Reads characters into a portion of an array, reading from the underlying stream if necessary.

readLine back to summary

readLine	back to summary
pack-priv String readLine(boolean ignoreLF, boolean[] term) 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'), a carriage return followed immediately by a line feed, or by reaching the end-of-file (EOF). Parameters ignoreLF:boolean If true, the next '\n' will be skipped term:boolean[] Output: Whether a line terminator was encountered while reading the line; may be `null`. Returns:String 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 without reading any characters Exceptions IOException: If an I/O error occurs See Also `java.io.LineNumberReader#readLine()`

pack-priv String readLine(boolean ignoreLF, boolean[] term) 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'), a carriage return followed immediately by a line feed, or by reaching the end-of-file (EOF).

Parameters

ignoreLF:boolean: If true, the next '\n' will be skipped
term:boolean[]: Output: Whether a line terminator was encountered while reading the line; may be null.

Returns:String

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 without reading any characters

Exceptions

IOException:: If an I/O error occurs

See Also

java.io.LineNumberReader#readLine()

readLine back to summary

readLine	back to summary
public 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'), a carriage return followed immediately by a line feed, or by reaching the end-of-file (EOF). Returns:String 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 without reading any characters Exceptions IOException: If an I/O error occurs See Also `java.nio.file.Files#readAllLines`

public String readLine() throws IOException

Returns:String

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 without reading any characters

Exceptions

IOException:: If an I/O error occurs

See Also

java.nio.file.Files#readAllLines

ready	back to summary
public boolean ready() throws IOException Overrides java.io.Reader.ready. 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. Exceptions IOException: If an I/O error occurs

ready

back to summary

public boolean ready() throws IOException

Overrides java.io.Reader.ready.

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.

Exceptions

IOException:: If an I/O error occurs

reset	back to summary
public void reset() throws IOException Overrides java.io.Reader.reset. Resets the stream to the most recent mark. Exceptions IOException: If the stream has never been marked, or if the mark has been invalidated

reset

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public void reset() throws IOException

Overrides java.io.Reader.reset.

Resets the stream to the most recent mark.

Exceptions

IOException:: If the stream has never been marked, or if the mark has been invalidated

skip	back to summary
public long skip(long n) throws IOException Overrides java.io.Reader.skip. Doc from java.io.Reader.skip. Skips characters. This method will block until some characters are available, an I/O error occurs, or the end of the stream is reached. If the stream is already at its end before this method is invoked, then no characters are skipped and zero is returned. Exceptions IOException: If an I/O error occurs

skip

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public long skip(long n) throws IOException

Overrides java.io.Reader.skip.

Doc from java.io.Reader.skip.

Skips characters. This method will block until some characters are available, an I/O error occurs, or the end of the stream is reached. If the stream is already at its end before this method is invoked, then no characters are skipped and zero is returned.

Exceptions

IOException:: If an I/O error occurs

public Class BufferedReader

Field Summary

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Method Summary

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