java.io

Class CharArrayReader

java.lang.Object

java.io.Reader

java.io.CharArrayReader

All Implemented Interfaces:

Closeable

public class CharArrayReader
extends Reader

This class permits an array of chars to be read as an input stream.

Author:

Aaron M. Renn (arenn@urbanophile.com), Warren Levy (warrenl@cygnus.com)

Constructor Summary

Constructors

Constructor and Description
CharArrayReader(char[] buffer) Create a new CharArrayReader that will read chars from the passed in char array.
CharArrayReader(char[] buffer, int offset, int length) Create a new CharArrayReader that will read chars from the passed in char array.

Method Summary

Modifier and Type	Method and Description
void	close() This method closes the stream.
void	mark(int readAheadLimit) This method sets the mark position in this stream to the current position.
boolean	markSupported() This method overrides the markSupported method in Reader in order to return true - indicating that this stream class supports mark/reset functionality.
int	read() This method reads one char from the stream.
int	read(char[] b, int off, int len) This method reads chars from the stream and stores them into a caller supplied buffer.
boolean	ready() Return true if more characters are available to be read.
void	reset() This method sets the read position in the stream to the mark point by setting the pos variable equal to the mark variable.
long	skip(long n) This method attempts to skip the requested number of chars in the input stream.

Methods inherited from class java.io.Reader

read

Methods inherited from class java.lang.Object

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

Constructor Detail

CharArrayReader

public CharArrayReader(char[] buffer)

Create a new CharArrayReader that will read chars from the passed in char array. This stream will read from the beginning to the end of the array. It is identical to calling an overloaded constructor as CharArrayReader(buf, 0, buf.length).

Note that this array is not copied. If its contents are changed while this stream is being read, those changes will be reflected in the chars supplied to the reader. Please use caution in changing the contents of the buffer while this stream is open.

Parameters:

buffer - The char array buffer this stream will read from.

CharArrayReader

public CharArrayReader(char[] buffer,
                       int offset,
                       int length)

Create a new CharArrayReader that will read chars from the passed in char array. This stream will read from position offset in the array for a length of length chars past offset. If the stream is reset to a position before offset then more than length chars can be read from the stream. The length value should be viewed as the array index one greater than the last position in the buffer to read.

Note that this array is not copied. If its contents are changed while this stream is being read, those changes will be reflected in the chars supplied to the reader. Please use caution in changing the contents of the buffer while this stream is open.

Parameters:

buffer - The char array buffer this stream will read from.

offset - The index into the buffer to start reading chars from

length - The number of chars to read from the buffer

Method Detail

close

public void close()

This method closes the stream.

Specified by:

close in interface Closeable

Specified by:

close in class Reader

mark

public void mark(int readAheadLimit)
          throws IOException

This method sets the mark position in this stream to the current position. Note that the readlimit parameter in this method does nothing as this stream is always capable of remembering all the chars int it.

Note that in this class the mark position is set by default to position 0 in the stream. This is in constrast to some other stream types where there is no default mark position.

Overrides:

mark in class Reader

Parameters:

readAheadLimit - The number of chars this stream must remember. This parameter is ignored.

Throws:

IOException - If an error occurs

markSupported

public boolean markSupported()

This method overrides the markSupported method in Reader in order to return true - indicating that this stream class supports mark/reset functionality.

Overrides:

markSupported in class Reader

Returns:

true to indicate that this class supports mark/reset.

read

public int read()
         throws IOException

This method reads one char from the stream. The pos counter is advanced to the next char to be read. The char read is returned as an int in the range of 0-65535. If the stream position is already at the end of the buffer, no char is read and a -1 is returned in order to indicate the end of the stream.

Overrides:

read in class Reader

Returns:

The char read, or -1 if end of stream

Throws:

IOException - If an error occurs

read

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

This method reads chars from the 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 if the end of the stream is encountered first. The actual number of chars read is returned. If no chars can be read because the stream is already at the end of stream position, a -1 is returned.

This method does not block.

Specified by:

read in class Reader

Parameters:

b - The array into which the chars read should be stored.

off - The offset into the array to start storing chars

len - 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.

ready

public boolean ready()
              throws IOException

Return true if more characters are available to be read.

Overrides:

ready in class Reader

Returns:

true to indicate that this stream is ready to be read.

Throws:

IOException - If an error occurs

reset

public void reset()
           throws IOException

This method sets the read position in the stream to the mark point by setting the pos variable equal to the mark variable. Since a mark can be set anywhere in the array, the mark/reset methods int this class can be used to provide random search capabilities for this type of stream.

Overrides:

reset in class Reader

Throws:

IOException - Always thrown for this class

skip

public long skip(long n)
          throws IOException

This method attempts to skip the requested number of chars in the input stream. It does this by advancing the pos value by the specified number of chars. It this would exceed the length of the buffer, then only enough chars are skipped to position the stream at the end of the buffer. The actual number of chars skipped is returned.

Overrides:

skip in class Reader

Parameters:

n - The requested number of chars to skip

Returns:

The actual number of chars skipped.

Throws:

IOException - If an error occurs