Java™ Platform
Standard Ed. 6

java.io
Class CharArrayReader

java.lang.Object
  extended by java.io.Reader
      extended by 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

Java™ Platform
Standard Ed. 6

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