(this, result));
+ message.sendToTarget();
+ return result;
+ }
+
+ /**
+ * Returns the current status of this task.
+ *
+ * @return The current status.
+ */
+ public final Status getStatus() {
+ return mStatus;
+ }
+
+ /**
+ * Override this method to perform a computation on a background thread. The
+ * specified parameters are the parameters passed to {@link #execute}
+ * by the caller of this task.
+ *
+ * This method can call {@link #publishProgress} to publish updates
+ * on the UI thread.
+ *
+ * @param params The parameters of the task.
+ *
+ * @return A result, defined by the subclass of this task.
+ *
+ * @see #onPreExecute()
+ * @see #onPostExecute
+ * @see #publishProgress
+ */
+ protected abstract Result doInBackground(Params... params);
+
+ /**
+ * Runs on the UI thread before {@link #doInBackground}.
+ *
+ * @see #onPostExecute
+ * @see #doInBackground
+ */
+ protected void onPreExecute() {
+ }
+
+ /**
+ * Runs on the UI thread after {@link #doInBackground}. The
+ * specified result is the value returned by {@link #doInBackground}.
+ *
+ * This method won't be invoked if the task was cancelled.
+ *
+ * @param result The result of the operation computed by {@link #doInBackground}.
+ *
+ * @see #onPreExecute
+ * @see #doInBackground
+ * @see #onCancelled(Object)
+ */
+ @SuppressWarnings({"UnusedDeclaration"})
+ protected void onPostExecute(Result result) {
+ }
+
+ /**
+ * Runs on the UI thread after {@link #publishProgress} is invoked.
+ * The specified values are the values passed to {@link #publishProgress}.
+ *
+ * @param values The values indicating progress.
+ *
+ * @see #publishProgress
+ * @see #doInBackground
+ */
+ @SuppressWarnings({"UnusedDeclaration"})
+ protected void onProgressUpdate(Progress... values) {
+ }
+
+ /**
+ * Runs on the UI thread after {@link #cancel(boolean)} is invoked and
+ * {@link #doInBackground(Object[])} has finished.
+ *
+ * The default implementation simply invokes {@link #onCancelled()} and
+ * ignores the result. If you write your own implementation, do not call
+ * super.onCancelled(result).
+ *
+ * @param result The result, if any, computed in
+ * {@link #doInBackground(Object[])}, can be null
+ *
+ * @see #cancel(boolean)
+ * @see #isCancelled()
+ */
+ @SuppressWarnings({"UnusedParameters"})
+ protected void onCancelled(Result result) {
+ onCancelled();
+ }
+
+ /**
+ * Applications should preferably override {@link #onCancelled(Object)}.
+ * This method is invoked by the default implementation of
+ * {@link #onCancelled(Object)}.
+ *
+ * Runs on the UI thread after {@link #cancel(boolean)} is invoked and
+ * {@link #doInBackground(Object[])} has finished.
+ *
+ * @see #onCancelled(Object)
+ * @see #cancel(boolean)
+ * @see #isCancelled()
+ */
+ protected void onCancelled() {
+ }
+
+ /**
+ * Returns true if this task was cancelled before it completed
+ * normally. If you are calling {@link #cancel(boolean)} on the task,
+ * the value returned by this method should be checked periodically from
+ * {@link #doInBackground(Object[])} to end the task as soon as possible.
+ *
+ * @return true if task was cancelled before it completed
+ *
+ * @see #cancel(boolean)
+ */
+ public final boolean isCancelled() {
+ return mCancelled.get();
+ }
+
+ /**
+ * Attempts to cancel execution of this task. This attempt will
+ * fail if the task has already completed, already been cancelled,
+ * or could not be cancelled for some other reason. If successful,
+ * and this task has not started when cancel is called,
+ * this task should never run. If the task has already started,
+ * then the mayInterruptIfRunning parameter determines
+ * whether the thread executing this task should be interrupted in
+ * an attempt to stop the task.
+ *
+ * Calling this method will result in {@link #onCancelled(Object)} being
+ * invoked on the UI thread after {@link #doInBackground(Object[])}
+ * returns. Calling this method guarantees that {@link #onPostExecute(Object)}
+ * is never invoked. After invoking this method, you should check the
+ * value returned by {@link #isCancelled()} periodically from
+ * {@link #doInBackground(Object[])} to finish the task as early as
+ * possible.
+ *
+ * @param mayInterruptIfRunning true if the thread executing this
+ * task should be interrupted; otherwise, in-progress tasks are allowed
+ * to complete.
+ *
+ * @return false if the task could not be cancelled,
+ * typically because it has already completed normally;
+ * true otherwise
+ *
+ * @see #isCancelled()
+ * @see #onCancelled(Object)
+ */
+ public final boolean cancel(boolean mayInterruptIfRunning) {
+ mCancelled.set(true);
+ return mFuture.cancel(mayInterruptIfRunning);
+ }
+
+ /**
+ * Waits if necessary for the computation to complete, and then
+ * retrieves its result.
+ *
+ * @return The computed result.
+ *
+ * @throws CancellationException If the computation was cancelled.
+ * @throws ExecutionException If the computation threw an exception.
+ * @throws InterruptedException If the current thread was interrupted
+ * while waiting.
+ */
+ public final Result get() throws InterruptedException, ExecutionException {
+ return mFuture.get();
+ }
+
+ /**
+ * Waits if necessary for at most the given time for the computation
+ * to complete, and then retrieves its result.
+ *
+ * @param timeout Time to wait before cancelling the operation.
+ * @param unit The time unit for the timeout.
+ *
+ * @return The computed result.
+ *
+ * @throws CancellationException If the computation was cancelled.
+ * @throws ExecutionException If the computation threw an exception.
+ * @throws InterruptedException If the current thread was interrupted
+ * while waiting.
+ * @throws TimeoutException If the wait timed out.
+ */
+ public final Result get(long timeout, TimeUnit unit) throws InterruptedException,
+ ExecutionException, TimeoutException {
+ return mFuture.get(timeout, unit);
+ }
+
+ /**
+ * Executes the task with the specified parameters. The task returns
+ * itself (this) so that the caller can keep a reference to it.
+ *
+ * Note: this function schedules the task on a queue for a single background
+ * thread or pool of threads depending on the platform version. When first
+ * introduced, AsyncTasks were executed serially on a single background thread.
+ * Starting with {@link android.os.Build.VERSION_CODES#DONUT}, this was changed
+ * to a pool of threads allowing multiple tasks to operate in parallel. Starting
+ * {@link android.os.Build.VERSION_CODES#HONEYCOMB}, tasks are back to being
+ * executed on a single thread to avoid common application errors caused
+ * by parallel execution. If you truly want parallel execution, you can use
+ * the {@link #executeOnExecutor} version of this method
+ * with {@link #THREAD_POOL_EXECUTOR}; however, see commentary there for warnings
+ * on its use.
+ *
+ *
This method must be invoked on the UI thread.
+ *
+ * @param params The parameters of the task.
+ *
+ * @return This instance of AsyncTask.
+ *
+ * @throws IllegalStateException If {@link #getStatus()} returns either
+ * {@link AsyncTask.Status#RUNNING} or {@link AsyncTask.Status#FINISHED}.
+ *
+ * @see #executeOnExecutor(Executor, Object[])
+ * @see #execute(Runnable)
+ */
+ public final AsyncTask execute(Params... params) {
+ return executeOnExecutor(sDefaultExecutor, params);
+ }
+
+ /**
+ * Executes the task with the specified parameters. The task returns
+ * itself (this) so that the caller can keep a reference to it.
+ *
+ * This method is typically used with {@link #THREAD_POOL_EXECUTOR} to
+ * allow multiple tasks to run in parallel on a pool of threads managed by
+ * AsyncTask, however you can also use your own {@link Executor} for custom
+ * behavior.
+ *
+ *
Warning: Allowing multiple tasks to run in parallel from
+ * a thread pool is generally not what one wants, because the order
+ * of their operation is not defined. For example, if these tasks are used
+ * to modify any state in common (such as writing a file due to a button click),
+ * there are no guarantees on the order of the modifications.
+ * Without careful work it is possible in rare cases for the newer version
+ * of the data to be over-written by an older one, leading to obscure data
+ * loss and stability issues. Such changes are best
+ * executed in serial; to guarantee such work is serialized regardless of
+ * platform version you can use this function with {@link #SERIAL_EXECUTOR}.
+ *
+ *
This method must be invoked on the UI thread.
+ *
+ * @param exec The executor to use. {@link #THREAD_POOL_EXECUTOR} is available as a
+ * convenient process-wide thread pool for tasks that are loosely coupled.
+ * @param params The parameters of the task.
+ *
+ * @return This instance of AsyncTask.
+ *
+ * @throws IllegalStateException If {@link #getStatus()} returns either
+ * {@link AsyncTask.Status#RUNNING} or {@link AsyncTask.Status#FINISHED}.
+ *
+ * @see #execute(Object[])
+ */
+ public final AsyncTask executeOnExecutor(Executor exec,
+ Params... params) {
+ if (mStatus != Status.PENDING) {
+ switch (mStatus) {
+ case RUNNING:
+ throw new IllegalStateException("Cannot execute task:"
+ + " the task is already running.");
+ case FINISHED:
+ throw new IllegalStateException("Cannot execute task:"
+ + " the task has already been executed "
+ + "(a task can be executed only once)");
+ }
+ }
+
+ mStatus = Status.RUNNING;
+
+ onPreExecute();
+
+ mWorker.mParams = params;
+ exec.execute(mFuture);
+
+ return this;
+ }
+
+ /**
+ * Convenience version of {@link #execute(Object...)} for use with
+ * a simple Runnable object. See {@link #execute(Object[])} for more
+ * information on the order of execution.
+ *
+ * @see #execute(Object[])
+ * @see #executeOnExecutor(Executor, Object[])
+ */
+ public static void execute(Runnable runnable) {
+ sDefaultExecutor.execute(runnable);
+ }
+
+ /**
+ * This method can be invoked from {@link #doInBackground} to
+ * publish updates on the UI thread while the background computation is
+ * still running. Each call to this method will trigger the execution of
+ * {@link #onProgressUpdate} on the UI thread.
+ *
+ * {@link #onProgressUpdate} will note be called if the task has been
+ * canceled.
+ *
+ * @param values The progress values to update the UI with.
+ *
+ * @see #onProgressUpdate
+ * @see #doInBackground
+ */
+ protected final void publishProgress(Progress... values) {
+ if (!isCancelled()) {
+ sHandler.obtainMessage(MESSAGE_POST_PROGRESS,
+ new AsyncTaskResult