Re: Strange exception when reading from a buffer
nooneinparticular314159@yahoo.com wrote:
I'm trying to read some data from a channel using java NIO. I create
a connection successfully, and then I try to read from the channel,
but I get the following error:
java.lang.ClassCastException: sun.nio.ch.ServerSocketChannelImpl
The following is the code that results in the error:
SocketChannel Channel;
By well-established Java convention, variable names begin with a lower-case
letter. Type names begin with an upper-case letter.
public ChannelReader(ByteBuffer ReceiveBuffer, SelectionKey InputKey)
{
this.ReceiveBuffer = ReceiveBuffer;
this.key = InputKey;
try {
Channel = (SocketChannel) InputKey.channel();
} catch (Throwable Exception) {
System.out.println("ChannelReader: ChannelReader:" +
Exception);
}
}
The error occurs on the line: Channel = (SocketChannel)
InputKey.channel();
What is causing this? How can I fix it?
What is causing the 'ClassCastException' is an attempt to cast an object of
one class or type, in this case some subclass of 'ServerSocketChannel', to an
incompatible type, in this case 'SocketChannel'. You cannot cast from a type
to another type that is not a superclass or subclass of the source type.
Here's how to research that sort of problem on your own:
<http://java.sun.com/javase/6/docs/api/java/lang/ClassCastException.html>
Thrown to indicate that the code has attempted to cast an object
to a subclass [sic] of which it is not an instance.
(They specify "subclass" because it is never necessary to cast to a superclass.)
'SocketChannel' is not a subclass of 'ServerSocketChannel', much less of
'sun.nio.ch.ServerSocketChannelImpl'.
--
Lew