org.apache.commons.io.input

Class UnsynchronizedBufferedReader

java.lang.Object

java.io.Reader

org.apache.commons.io.input.UnsynchronizedReader

org.apache.commons.io.input.UnsynchronizedBufferedReader

All Implemented Interfaces:

Closeable, AutoCloseable, Readable

public class UnsynchronizedBufferedReader
extends UnsynchronizedReader

Wraps an existing Reader and buffers the input without any synchronization. Expensive interaction with the underlying reader is minimized, since most (smaller) requests can be satisfied by accessing the buffer alone. The drawback is that some extra space is required to hold the buffer and that copying takes place when filling that buffer, but this is usually outweighed by the performance benefits.

A typical application pattern for the class looks like this:

 UnsynchronizedBufferedReader buf = new UnsynchronizedBufferedReader(new FileReader("file"));
 

Provenance: Apache Harmony's java.io.BufferedReader, renamed, and modified.

See Also:

BufferedReader, BufferedWriter

Field Summary

Fields inherited from class java.io.Reader

lock

Constructor Summary

Constructors

Constructor and Description
UnsynchronizedBufferedReader(Reader in) Constructs a new BufferedReader on the Reader in.
UnsynchronizedBufferedReader(Reader in, int size) Constructs a new BufferedReader on the Reader in.

Method Summary

Modifier and Type	Method and Description
(package private) void	chompNewline() Peeks at the next input character, refilling the buffer if necessary.
void	close() Closes this reader.
void	mark(int markLimit) Sets a mark position in this reader.
boolean	markSupported() Tests whether this reader supports the mark(int) and reset() methods.
int	peek() Returns the next character in the current reader without consuming it.
int	peek(char[] buf) Populates the buffer with the next buf.length characters in the current reader without consuming them.
int	read() Reads a single character from this reader and returns it with the two higher-order bytes set to 0.
int	read(char[] buffer, int offset, int length) Reads at most length characters from this reader and stores them at offset in the character array buffer.
String	readLine() Returns the next line of text available from this reader.
boolean	ready() Tests whether this reader is ready to be read without blocking.
void	reset() Resets this reader's position to the last mark() location.
long	skip(long amount) Skips amount characters in this reader.

Methods inherited from class org.apache.commons.io.input.UnsynchronizedReader

checkOpen, isClosed, setClosed

Methods inherited from class java.io.Reader

read, read

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

UnsynchronizedBufferedReader

public UnsynchronizedBufferedReader(Reader in)

Constructs a new BufferedReader on the Reader in. The buffer gets the default size (8 KB).

Parameters:

in - the Reader that is buffered.

UnsynchronizedBufferedReader

public UnsynchronizedBufferedReader(Reader in,
                                    int size)

Constructs a new BufferedReader on the Reader in. The buffer size is specified by the parameter size.

Parameters:

in - the Reader that is buffered.

size - the size of the buffer to allocate.

Throws:

IllegalArgumentException - if size <= 0.

Method Detail

chompNewline

final void chompNewline()
                 throws IOException

Peeks at the next input character, refilling the buffer if necessary. If this character is a newline character ("\n"), it is discarded.

Throws:

IOException

close

public void close()
           throws IOException

Closes this reader. This implementation closes the buffered source reader and releases the buffer. Nothing is done if this reader has already been closed.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class UnsynchronizedReader

Throws:

IOException - if an error occurs while closing this reader.

mark

public void mark(int markLimit)
          throws IOException

Sets a mark position in this reader. The parameter markLimit indicates how many characters can be read before the mark is invalidated. Calling reset() will reposition the reader back to the marked position if markLimit has not been surpassed.

Overrides:

mark in class Reader

Parameters:

markLimit - the number of characters that can be read before the mark is invalidated.

Throws:

IllegalArgumentException - if markLimit < 0.

IOException - if an error occurs while setting a mark in this reader.

See Also:

markSupported(), reset()

markSupported

public boolean markSupported()

Tests whether this reader supports the mark(int) and reset() methods. This implementation returns true.

Overrides:

markSupported in class Reader

Returns:

true for BufferedReader.

See Also:

mark(int), reset()

peek

public int peek()
         throws IOException

Returns the next character in the current reader without consuming it. So the next call to read() will still return this value.

Returns:

the next character

Throws:

IOException - If an I/O error occurs

peek

public int peek(char[] buf)
         throws IOException

Populates the buffer with the next buf.length characters in the current reader without consuming them. The next call to read() will still return the next value.

Parameters:

buf - the buffer to fill for the look ahead.

Returns:

the buffer itself

Throws:

IOException - If an I/O error occurs

read

public int read()
         throws IOException

Reads a single character from this reader and returns it with the two higher-order bytes set to 0. If possible, BufferedReader returns a character from the buffer. If there are no characters available in the buffer, it fills the buffer and then returns a character. It returns -1 if there are no more characters in the source reader.

Overrides:

read in class Reader

Returns:

the character read or -1 if the end of the source reader has been reached.

Throws:

IOException - if this reader is closed or some other I/O error occurs.

read

public int read(char[] buffer,
                int offset,
                int length)
         throws IOException

Reads at most length characters from this reader and stores them at offset in the character array buffer. Returns the number of characters actually read or -1 if the end of the source reader has been reached. If all the buffered characters have been used, a mark has not been set and the requested number of characters is larger than this readers buffer size, BufferedReader bypasses the buffer and simply places the results directly into buffer.

Specified by:

read in class Reader

Parameters:

buffer - the character array to store the characters read.

offset - the initial position in buffer to store the bytes read from this reader.

length - the maximum number of characters to read, must be non-negative.

Returns:

number of characters read or -1 if the end of the source reader has been reached.

Throws:

IndexOutOfBoundsException - if offset < 0 or length < 0, or if offset + length is greater than the size of buffer.

IOException - if this reader is closed or some other I/O error occurs.

readLine

public String readLine()
                throws IOException

Returns the next line of text available from this reader. A line is represented by zero or more characters followed by LF, CR, "\r\n" or the end of the reader. The string does not include the newline sequence.

Returns:

the contents of the line or null if no characters were read before the end of the reader has been reached.

Throws:

IOException - if this reader is closed or some other I/O error occurs.

ready

public boolean ready()
              throws IOException

Tests whether this reader is ready to be read without blocking.

Overrides:

ready in class Reader

Returns:

true if this reader will not block when read is called, false if unknown or blocking will occur.

Throws:

IOException - if this reader is closed or some other I/O error occurs.

See Also:

read(), read(char[], int, int), readLine()

reset

public void reset()
           throws IOException

Resets this reader's position to the last mark() location. Invocations of read() and skip() will occur from this new location.

Overrides:

reset in class Reader

Throws:

IOException - if this reader is closed or no mark has been set.

See Also:

mark(int), markSupported()

skip

public long skip(long amount)
          throws IOException

Skips amount characters in this reader. Subsequent read()s will not return these characters unless reset() is used. Skipping characters may invalidate a mark if markLimit is surpassed.

Overrides:

skip in class UnsynchronizedReader

Parameters:

amount - the maximum number of characters to skip.

Returns:

the number of characters actually skipped.

Throws:

IllegalArgumentException - if amount < 0.

IOException - if this reader is closed or some other I/O error occurs.

See Also:

mark(int), markSupported(), reset()