bayou.util

Class End

java.lang.Object

java.lang.Throwable

java.lang.Exception

bayou.util.End

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

WebSocketClose

public class End
extends Exception

A control exception for signaling that something has reached its end.

For example, AsyncIterator.next() either succeeds with the next item, or fails with an End if there are no more items.

Other APIs, for example ByteSource.read(), also use End as the control exception, to be compatible with AsyncIterator.next().

Some APIs create subtypes of End to carry more information. For example, WebSocketClose, a subtype of End, contains code/reason for the closure of a WebSocket channel inbound/outbound.

Being a control exception, an End does not really represent an exceptional condition; it is more of a sentinel value for an API. An End contains no stacktrace and is cheap to create. It is immutable, with enableSuppression=writableStackTrace=false, see explanation in Throwable(message, cause, enableSuppression, writableStackTrace). It's safe to share an End object due to immutability.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
End() Create an End exception.
End(String message) Create an End exception.
End(String message, Throwable cause) Create an End exception.

Method Summary

Static Methods
End	instance() Return an End instance.
<T> Async<T>	async() Return an `Async<T>` that immediately fails with an End exception.

Methods inherited from class java.lang.Throwable

addSuppressed, fillInStackTrace, getCause, getLocalizedMessage, getMessage, getStackTrace, getSuppressed, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

End

public End()

Create an End exception.

End

public End(String message)

Create an End exception.

End

public End(String message,
           Throwable cause)

Create an End exception.

Method Detail

instance

public static End instance()

Return an End instance.

Semantically equivalent to `new End()`, but this method may return a cached object.

Example Usage:

     action
         .then( v->
         {
             if(condition)
                 throw End.instance();
             ...
         }
 

async

public static <T> Async<T> async()

Return an `Async<T>` that immediately fails with an End exception.

Semantically equivalent to `Async.failure(new End())`, but this method may return a cached object.

Often used as a return value in an Async method, for example:

     public Async<ByteBuffer> read()
     {
         if( eof_reached )
             return End.async();
         ...
     }