java.io

Class CharArrayReader

public class CharArrayReader extends Reader

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

Field Summary
protected char[]	buf The array that contains the data supplied during read operations
protected int	count This indicates the maximum number of chars that can be read from this stream.
protected int	markedPos The currently marked position in the stream.
protected int	pos The array index of the next char to be read from the buffer `buf`

Constructor Summary
	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
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.

Field Detail

buf

protected char[] buf

The array that contains the data supplied during read operations

count

protected int count

This indicates the maximum number of chars that can be read from this stream. It is the array index of the position after the last valid char in the buffer buf

The currently marked position in the stream. This defaults to 0, so a reset operation on the stream resets it to read from array index 0 in the buffer - even if the stream was initially created with an offset greater than 0

pos

protected int pos

The array index of the next char to be read from the buffer buf

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.

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.

mark

public void mark(int readAheadLimit)

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.

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.

Returns: true to indicate that this class supports mark/reset.

read

public int read()

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.

Returns: The char read, or -1 if end of stream

read

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

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.

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.

ready

public boolean ready()

Return true if more characters are available to be read.

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

UNKNOWN: The JDK 1.3 API docs are wrong here. This method will return false if there are no more characters available.

reset

public 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. 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.

skip

public long skip(long n)

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.

Parameters: n The requested number of chars to skip

Returns: The actual number of chars skipped.