org.openide.util

Class Task

java.lang.Object

org.openide.util.Task

All Implemented Interfaces:

Runnable

Direct Known Subclasses:

RequestProcessor.Task

public class Task
extends Object
implements Runnable

A task that may be executed in a separate thread and permits examination of its status. Other threads can check if it is finished or wait for it to finish.

For example:

 Runnable r = new Runnable () {
   public void run () {
     // do something
   }
 };
 Task task = new Task (r);
 RequestProcessor.postRequest (task);
 

In a different thread one can then test task.isFinished () or wait for it with task.waitFinished ().

Field Summary

Fields

Modifier and Type	Field and Description
static Task	EMPTY Dummy task which is already finished.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Task() Constructor for subclasses that wants to control whole execution itself.
	Task(Runnable run) Create a new task.

Method Summary

Modifier and Type	Method and Description
void	addTaskListener(TaskListener l) Add a listener to the task.
boolean	isFinished() Test whether the task has finished running.
protected void	notifyFinished() Notify all waiters that this task has finished.
protected void	notifyRunning() Changes the state of the task to be running.
void	removeTaskListener(TaskListener l) Remove a listener from the task.
void	run() Start the task.
String	toString()
void	waitFinished() Wait until the task is finished.
boolean	waitFinished(long milliseconds) Wait until the task is finished, but only a given time.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY

public static final Task EMPTY

Dummy task which is already finished.

Constructor Detail

Task

public Task(Runnable run)

Create a new task. The runnable should provide its own error-handling, as by default thrown exceptions are simply logged and not rethrown.

Parameters:

run - runnable to run that computes the task

Task

protected Task()

Constructor for subclasses that wants to control whole execution itself.

Since:

1.5

Method Detail

isFinished

public final boolean isFinished()

Test whether the task has finished running.

Returns:

true if so

waitFinished

public void waitFinished()

Wait until the task is finished. Changed not to be final in version 1.5

waitFinished

public boolean waitFinished(long milliseconds)
                     throws InterruptedException

Wait until the task is finished, but only a given time. waitFinished(0) means indefinite timeout (similar to wait(0))

Parameters:

milliseconds - time in milliseconds to wait for the result

Returns:

true if the task is really finished, or false if the time out has been exceeded

Throws:

InterruptedException - when the waiting has been interrupted

Since:

5.0

notifyRunning

protected final void notifyRunning()

Changes the state of the task to be running. Any call after this one and before notifyFinished to waitFinished blocks.

Since:

1.5

notifyFinished

protected final void notifyFinished()

Notify all waiters that this task has finished.

See Also:

Task.run()

run

public void run()

Start the task. When it finishes (even with an exception) it calls Task.notifyFinished(). Subclasses may override this method, but they then need to call Task.notifyFinished() explicitly.

Note that this call runs synchronously, but typically the creator of the task will call this method in a separate thread.

Specified by:

run in interface Runnable

addTaskListener

public void addTaskListener(TaskListener l)

Add a listener to the task. The listener will be called once the task Task.isFinished(). In case the task is already finished, the listener is called immediately.

Parameters:

l - the listener to add

removeTaskListener

public void removeTaskListener(TaskListener l)

Remove a listener from the task.

Parameters:

l - the listener to remove

toString

public String toString()

Overrides:

toString in class Object