java.io

Class BufferedReader

Implemented Interfaces:
AutoCloseable, Closeable, Readable
Known Direct Subclasses:
LineNumberReader

public class BufferedReader
extends Reader

This subclass of FilterReader buffers input from an underlying implementation to provide a possibly more efficient read mechanism. It maintains the buffer and buffer state in instance variables that are available to subclasses. The default buffer size of 8192 chars can be overridden by the creator of the stream.

This class also implements mark/reset functionality. It is capable of remembering any number of input chars, to the limits of system memory or the size of Integer.MAX_VALUE

Field Summary

Fields inherited from class java.io.Reader

lock

Constructor Summary

BufferedReader(Reader in)
Create a new BufferedReader that will read from the specified subordinate stream with a default buffer size of 8192 chars.
BufferedReader(Reader in, int size)
Create a new BufferedReader that will read from the specified subordinate stream with a buffer size that is specified by the caller.

Method Summary

void
close()
This method closes the underlying stream and frees any associated resources.
void
mark(int readLimit)
Mark a position in the input to which the stream can be "reset" by calling the reset() method.
boolean
markSupported()
Returns true to indicate that this class supports mark/reset functionality.
int
read()
int
read(char[] buf, int offset, int count)
This method read chars from a stream and stores them into a caller supplied buffer.
String
readLine()
This method reads a single line of text from the input stream, returning it as a String.
boolean
ready()
This method determines whether or not a stream is ready to be read.
void
reset()
Reset the stream to the point where the mark() method was called.
long
skip(long count)
This method skips the specified number of chars in the stream.

Methods inherited from class java.io.Reader

close, mark, markSupported, read, read, read, read, ready, reset, skip

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

BufferedReader

public BufferedReader(Reader in)
Create a new BufferedReader that will read from the specified subordinate stream with a default buffer size of 8192 chars.
Parameters:
in - The subordinate stream to read from

BufferedReader

public BufferedReader(Reader in,
                      int size)
Create a new BufferedReader that will read from the specified subordinate stream with a buffer size that is specified by the caller.
Parameters:
in - The subordinate stream to read from
size - The buffer size to use
Throws:
IllegalArgumentException - if size <= 0

Method Details

close

public void close()
            throws IOException
This method closes the underlying stream and frees any associated resources.
Specified by:
close in interface Closeable
close in interface AutoCloseable
Overrides:
close in interface Reader
Throws:
IOException - If an error occurs

mark

public void mark(int readLimit)
            throws IOException
Mark a position in the input to which the stream can be "reset" by calling the reset() method. The parameter readLimit is the number of chars that can be read from the stream after setting the mark before the mark becomes invalid. For example, if mark() is called with a read limit of 10, then when 11 chars of data are read from the stream before the reset() method is called, then the mark is invalid and the stream object instance is not required to remember the mark.

Note that the number of chars that can be remembered by this method can be greater than the size of the internal read buffer. It is also not dependent on the subordinate stream supporting mark/reset functionality.

Overrides:
mark in interface Reader
Parameters:
readLimit - The number of chars that can be read before the mark becomes invalid
Throws:
IOException - If an error occurs
IllegalArgumentException - if readLimit is negative.

markSupported

public boolean markSupported()
Returns true to indicate that this class supports mark/reset functionality.
Overrides:
markSupported in interface Reader
Returns:
true

read

public int read()
            throws IOException
Overrides:
read in interface Reader

read

public int read(char[] buf,
                int offset,
                int count)
            throws IOException
This method read chars from a stream and stores them into a caller supplied buffer. It starts storing the data at index offset into the buffer and attempts to read len chars. This method can return before reading the number of chars requested. The actual number of chars read is returned as an int. A -1 is returned to indicate the end of the stream.

This method will block until some data can be read.

Parameters:
buf - The array into which the chars read should be stored
offset - The offset into the array to start storing chars
count - The requested number of chars to read
Returns:
The actual number of chars read, or -1 if end of stream.
Throws:
IOException - If an error occurs.
IndexOutOfBoundsException - If offset and count are not valid regarding buf.

readLine

public String readLine()
            throws IOException
This method reads a single line of text from the input stream, returning it as a String. A line is terminated by "\n", a "\r", or an "\r\n" sequence. The system dependent line separator is not used. The line termination characters are not returned in the resulting String.
Returns:
The line of text read, or null if end of stream.
Throws:
IOException - If an error occurs

ready

public boolean ready()
            throws IOException
This method determines whether or not a stream is ready to be read. If this method returns false then this stream could (but is not guaranteed to) block on the next read attempt.
Overrides:
ready in interface Reader
Returns:
true if this stream is ready to be read, false otherwise
Throws:
IOException - If an error occurs

reset

public void reset()
            throws IOException
Reset the stream to the point where the mark() method was called. Any chars that were read after the mark point was set will be re-read during subsequent reads.

This method will throw an IOException if the number of chars read from the stream since the call to mark() exceeds the mark limit passed when establishing the mark.

Overrides:
reset in interface Reader
Throws:
IOException - If an error occurs;

skip

public long skip(long count)
            throws IOException
This method skips the specified number of chars in the stream. It returns the actual number of chars skipped, which may be less than the requested amount.

This method first discards chars in the buffer, then calls the skip method on the underlying stream to skip the remaining chars.

Overrides:
skip in interface Reader
Parameters:
count - The requested number of chars to skip
Returns:
The actual number of chars skipped.
Throws:
IOException - If an error occurs.
IllegalArgumentException - If count is negative.

BufferedReader.java Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.