java.io
Class CharArrayReader

java.lang.Object
  java.io.Reader
      java.io.CharArrayReader

All Implemented Interfaces:

Closeable, Readable

public class CharArrayReader
extends Reader

This class implements a character buffer that can be used as a character-input stream.

Since:

JDK1.1

Field Summary

protected char[]	buf The character buffer.
protected int	count The index of the end of this buffer.
protected int	markedPos The position of mark in buffer.
protected int	pos The current buffer position.

Fields inherited from class java.io.Reader

lock

Constructor Summary

CharArrayReader(char[] buf)
Creates a CharArrayReader from the specified array of chars.

CharArrayReader(char[] buf, int offset, int length)
Creates a CharArrayReader from the specified array of chars.

Method Summary

void	close() Closes the stream and releases any system resources associated with it.
void	mark(int readAheadLimit) Marks the present position in the stream.
boolean	markSupported() Tells whether this stream supports the mark() operation, which it does.
int	read() Reads a single character.
int	read(char[] b, int off, int len) Reads characters into a portion of an array.
boolean	ready() Tells whether this stream is ready to be read.
void	reset() Resets the stream to the most recent mark, or to the beginning if it has never been marked.
long	skip(long n) Skips characters.

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

Field Detail

buf

protected char[] buf

The character buffer.

pos

protected int pos

The current buffer position.

markedPos

protected int markedPos

The position of mark in buffer.

count

protected int count

The index of the end of this buffer. There is not valid data at or beyond this index.

Constructor Detail

CharArrayReader

public CharArrayReader(char[] buf)

Creates a CharArrayReader from the specified array of chars.

Parameters:

buf - Input buffer (not copied)

CharArrayReader

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

Creates a CharArrayReader from the specified array of chars.

The resulting reader will start reading at the given offset. The total number of char values that can be read from this reader will be either length or buf.length-offset, whichever is smaller.

Parameters:

buf - Input buffer (not copied)

offset - Offset of the first char to read

length - Number of chars to read

Throws:

IllegalArgumentException - If offset is negative or greater than buf.length, or if length is negative, or if the sum of these two values is negative.

Method Detail

read

public int read()
         throws IOException

Reads a single character.

Overrides:

read in class Reader

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

Throws:

IOException - If an I/O error occurs

read

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

Reads characters into a portion of an array.

Specified by:

read in class Reader

Parameters:

b - Destination buffer

off - Offset at which to start storing characters

len - Maximum number of characters to read

Returns:

The actual number of characters read, or -1 if the end of the stream has been reached

Throws:

IOException - If an I/O error occurs

skip

public long skip(long n)
          throws IOException

Skips characters. Returns the number of characters that were skipped.

The n parameter may be negative, even though the skip method of the Reader superclass throws an exception in this case. If n is negative, then this method does nothing and returns 0.

Overrides:

skip in class Reader

Parameters:

n - The number of characters to skip

Returns:

The number of characters actually skipped

Throws:

IOException - If the stream is closed, or an I/O error occurs

ready

public boolean ready()
              throws IOException

Tells whether this stream is ready to be read. Character-array readers are always ready to be read.

Overrides:

ready in class Reader

Returns:

True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.

Throws:

IOException - If an I/O error occurs

markSupported

public boolean markSupported()

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

Overrides:

markSupported in class Reader

Returns:

true if and only if this stream supports the mark operation.

mark

public void mark(int readAheadLimit)
          throws IOException

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

Overrides:

mark in class Reader

Parameters:

readAheadLimit - Limit on the number of characters that may be read while still preserving the mark. Because the stream's input comes from a character array, there is no actual limit; hence this argument is ignored.

Throws:

IOException - If an I/O error occurs

reset

public void reset()
           throws IOException

Resets the stream to the most recent mark, or to the beginning if it has never been marked.

Overrides:

reset in class Reader

Throws:

IOException - If an I/O error occurs

close

public void 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.

Specified by:

close in interface Closeable

Specified by:

close in class Reader