/*MujMail - Simple mail client for J2MECopyright (C) 2009 David Hauzar <david.hauzar.mujmail@gmail.com>This program is free software; you can redistribute it and/or modifyit under the terms of the GNU General Public License as published bythe Free Software Foundation; either version 2 of the License, or(at your option) any later version.This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See theGNU General Public License for more details.You should have received a copy of the GNU General Public Licensealong with this program; if not, write to the Free SoftwareFoundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */package mujmail.tasks;import java.util.Vector;import javax.microedition.lcdui.Displayable;import mujmail.util.Observable;import mujmail.util.Observer;/** * Static class for managing background tasks and getting information about them. * *  * @author David Hauzar */public class TasksManager {    static ChangableObservable endTaskObservable = new ChangableObservable();    static ChangableObservable startTaskObservable = new ChangableObservable();    static final int MAXIMUM_NUMBER_OF_RUNNING_TASKS = 2;    private static class ChangableObservable extends Observable {        public void setChanged() {            super.setChanged();        }    }    /**     * Checks whether there are some tasks running and if not, exits the     * application.     * If there are some tasks running, exits the application when all tasks     * will terminate. In this case it alsodisplays the dialog to user in that     * user can cancel exiting or confirm exiting despite of some tasks are     * running.     */    public static void conditionallyExit() {        ConditionalActionRunner exitActionRunner = new ConditionalActionRunner(                ConditionalActionRunner.ExitApplicationCondition.CONDITION,                ConditionalActionRunner.ExitApplicationAction.ACTION);        exitActionRunner.startAction(                new ConditionalActionRunnerUI(                    exitActionRunner,                    "Some tasks are still running",                    "There are incompleted tasks that are still running. The application will exit automatically when all will terminate.",                    "Exit anyway"));    }    /**     * Returns true if some task is running or waiting to start.     * @return true if some task is running or waiting to start.     */    public static boolean isSomeTaskRunningOrWaitingToStart() {        return !BackgroundTask.getRunningTasks().isEmpty() || ConditionalActionRunner.ConditionalTaskRunner.getNumberOfTasksWaitingForStart() != 0;    }    /**     * Gets the number of tasks either running or waiting to be started.     * @return the number of tasks either running or waiting to be started.     */    public static int numTasks() {        return BackgroundTask.getRunningTasks().size() + ConditionalActionRunner.ConditionalTaskRunner.getNumberOfTasksWaitingForStart();    }    /**     * Adds observer that will be notified whenever some task will end.     * @param endTaskObserver the object that will be notified whenever the some     *  task will end.     *  The argument of function notify will be the task that actually ended.     *  That is the object of type BackgroundTask.     * @see Observable#addObserver(mujmail.util.Observer)      */    public static void addEndTaskObserver(Observer endTaskObserver) {        endTaskObservable.addObserver(endTaskObserver);    }    /**     * Deletes observer that is notified whenever some task ends. This observer     * will be not notified any more.     * @param endTaskObserver the observer to be deleted.     * @see Observable#deleteObserver(mujmail.util.Observer)     */    public static void deleteEndTaskObserver(Observer endTaskObserver) {        endTaskObservable.deleteObserver(endTaskObserver);    }    /**     * Deletes all observers that are notified whenever some task ends. This     * observers will be not notified any more.     * @see Observable#deleteObservers()     */    public static void deleteEndTaskObservers() {        endTaskObservable.deleteObservers();    }    /**     * Adds observer that will be notified whenever some task will start.     * @param startTaskObserver the object that will be notified whenever the some     *  task will start.     *  The argument of function notify will be the task that actually started.     *  That is the object of type BackgroundTask.     * @see Observable#addObserver(mujmail.util.Observer)     */    public static void addStartTaskObserver(Observer startTaskObserver) {        startTaskObservable.addObserver(startTaskObserver);    }    /**     * Deletes observer that is notified whenever some task starts. This observer     * will be not notified any more.     * @param startTaskObserver the observer to be deleted.     * @see Observable#deleteObserver(mujmail.util.Observer)     */    public static void deleteStartTaskObserver(Observer startTaskObserver) {        startTaskObservable.deleteObserver(startTaskObserver);    }    /**     * Deletes all observers that are notified whenever some task starts. This     * observers will be not notified any more.     * @see Observable#deleteObservers()     */    public static void deleteStartTaskObservers() {        startTaskObservable.deleteObservers();    }    /**     * Do all task manager actions with task that actually ended.     * This method is called by BackgroundTask whenever the task ends.     * @param backgroundTask the task that ended     */    static void taskEnded(BackgroundTask backgroundTask) {        endTaskObservable.setChanged();        endTaskObservable.notifyObservers(backgroundTask);    }    /**     * Do all task manager action with task that actually started.     * This method is called by BackgroundTask whenever the task starts.     * @param backgroundTask the task that starts.     */    static void taskStarted(BackgroundTask backgroundTask) {        startTaskObservable.setChanged();        startTaskObservable.notifyObservers(backgroundTask);    }    /**     * Sets given screen as screen that will be displayed after termination     * of the task or pressing back button to all running tasks.     * @param screen the screen to be set.     */    public static void setScreenToAllTasks(Displayable screen) {        Vector allTasks = BackgroundTask.getRunningTasks();        for (int i = 0; i < allTasks.size(); i++) {            BackgroundTask task;            try {                task = (BackgroundTask) allTasks.elementAt(i);            } catch (Exception e) {                break;            }            task.setNextScreen(screen);            task.getProgressManager().setPrevScreen(screen);        }    }    /**     * Gets the Vector of running tasks.     * @return Vector of running tasks.     */    public static Vector getRunningTasks() {        return BackgroundTask.getRunningTasks();    }}