org.jbrew.concurrent

Class RetrievableTask<T>

java.lang.Object

org.jbrew.concurrent.AbstractTask<T>

org.jbrew.concurrent.RetrievableTask<T>

Type Parameters:

T - - The type of object the programmer wishes to operate upon.

All Implemented Interfaces:

Runnable, Task<T>

Direct Known Subclasses:

MethodBlockingTask, ObjectBlockingTask

public abstract class RetrievableTask<T>
extends AbstractTask<T>

A AbstractTask that returns a result. Implementors must define a single method with no arguments called execute. In these manners, a RetrievableTask is similar to a BasicTask and Callable in that the former is designed for classes whose instances can be potentially wrapped in another thread - while the latter also returns a result. Unlike a Callable however, a RetrievableTask does not natively throw an exception, although certain flagship methods may, such as retrieve().

For a non-returnable implementation of an AbstractTask, please refer to BasicTask.

Author:

nealk

See Also:

AbstractTask, ObjectBlockingTask, MethodBlockingTask, BasicTask

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	printThreadIdFlag

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	RetrievableTask() The default, noargs constructor for RetrievableTask.
protected	RetrievableTask(boolean printThreadIdFlag) This constructor takes a boolean argument to determine whether the thread number should be printed to the console.

Method Summary

Modifier and Type	Method and Description
protected abstract void	accept(T obj) Sets the value of the obj in a ThreadSafe manner.
abstract T	retrieve() Returns the value of the obj in a ThreadSafe manner.

Methods inherited from class org.jbrew.concurrent.AbstractTask

execute, getName, getPriority, getThreadId, run, setName, setPriority

Methods inherited from class java.lang.Object

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

Field Detail

printThreadIdFlag

protected boolean printThreadIdFlag

Constructor Detail

RetrievableTask

protected RetrievableTask()

The default, noargs constructor for RetrievableTask. This can be wrapped inside of a Thread and executed in the same manner as a Callable.

RetrievableTask

protected RetrievableTask(boolean printThreadIdFlag)

This constructor takes a boolean argument to determine whether the thread number should be printed to the console. A RetrievableTask can be wrapped inside of a Thread and executed in the same manner as a Callable.

Parameters:

printThreadIdFlag - - boolean flag which specifies whether thread number should be printed to the console.

Method Detail

accept

protected abstract void accept(T obj)

Sets the value of the obj in a ThreadSafe manner.

Parameters:

obj - The object to set.

retrieve

public abstract T retrieve()
                    throws InterruptedException

Returns the value of the obj in a ThreadSafe manner. The method blocks until a condition is met (such as the excute() method returning or the obj of type <T> being set (via the setVal() method). For more information on the way internal contention is handled, please refer to MethodBlockingTask and ObjectBlockingTask.

Please note that Java generics are used for the programmer to explicitly define the Type when extending this class.
  Example:
      public class TaskImplementor<T> implements Task<ConcreteClass>{ }

Returns:

value of obj - with type <T>

Throws:

InterruptedException - is thrown if the thread is interrupted.

See Also:

ObjectBlockingTask, MethodBlockingTask