I'm currently working on ListViews in Fragments. The Listviews are loaded by Cursorloader, but without ContentManager. So the code looks like this and it works:
#Override
public Loader<Cursor> onCreateLoader(int arg0, Bundle arg1) {
Log.d("SoapERP", "onCreateLoader");
CursorLoader loader = new CursorLoader(getActivity()) {
final DBHelper dbhelper1= new DBHelper(getActivity());
#Override
public Cursor loadInBackground() {
Cursor c = null;
dbhelper1.open();
c = dbhelper1.fetchAllMatnameswithID();
// dbhelper1.close();
return c;
}
};
return loader;
My problem is that I get an LogCat-Error-Message that the database wasn't closed. But if I use dbhelper.close(); I get the Error "Database is already closed" wich is also understandable because it is just before the return statement. After the return statement code is not reachable and if I declare DBHelper dbhelper1 final the program crashes without any information in logcat. So what is my fail???
Finally I found here the right statement as of Dianne Hackborn from android framework development: "A content provider is created when its hosting process is created, and remains around for as long as the process does, so there is no need to close the database -- it will get closed as part of the kernel cleaning up the process's resources when the process is killed. Dianne Hackborn Android framework engineer hack...#android.com " - so let's use Content Provider.
Related
How can I dispose and re-instantiate a singleton with Prism/DryIoC in Xamarin Forms?
I'm working with Azure Mobile Apps for offline data. Occasionally, I need to delete the local sqlite database and re-initialize it. Unfortunately the MobileServiceClient occasionally holds the db connection open and there's no method exposed to close it. The suggested solution (https://github.com/Azure/azure-mobile-apps-net-client/issues/379) is to dispose of MobileServiceClient. Only problem is that is registered with DryIoC as a singleton.
I'm not overly familiar with DryIoC, or Prism and Forms for that matter... But for the life of me, I can't see a way to do this.
I did cook up a pretty elaborate scheme that almost worked.
In my ViewModel method, when I needed the db freed up, I fired off an event -
_eventAggregator.GetEvent<RegisterDatabaseEvent>().Publish(false);
Then in App.xaml.cs, I wired up a listener and a handler like so -
_eventAggregator.GetEvent<RegisterDatabaseEvent>().Subscribe(OnRegisterDatabaseEventPublished);
private void OnRegisterDatabaseEventPublished()
{
Container.GetContainer().Unregister<IAppMobileClient>();
Container.GetContainer().Unregister<IMobileServiceClient>();
Container.GetContainer().Register<IMobileServiceClient, AppMobileClient>(new SingletonReuse());
Container.GetContainer().Register<IAppMobileClient, AppMobileClient>(new SingletonReuse());
_eventAggregator.GetEvent<RegisterDatabaseCompletedEvent>().Publish(register);
}
Lastly, back in the ViewModel constructor, I had a final listener that handled the event coming back from App.xaml and finished processing.
_eventAggregator.GetEvent<RegisterDatabaseCompletedEvent>().Subscribe(OnRegisterDatabaseCompletedEventPublished);
So the amazing thing is that this worked. The database was able to be deleted and all was good. But then I navigated to a different page and BOOM. DryIoC said it couldn't wire up the ViewModel for that page. I assume the unregister/register jacked up DryIoC for all injection... So how can I accomplish what needs to be done?
FINAL SOLUTION
Thanks so much to dadhi for taking the time to help. You are certainly a class act and I'm now considering using DryIoC elsewhere.
For anyone who stumbles on this, I'm posting the final solution below. I'll be as verbose as I can to avoid any confusion.
First, in my App.xaml.cs, I added a method for registering my database.
public void RegisterDatabase(IContainer container)
{
container.RegisterMany<AppMobileClient>(Reuse.Singleton,
setup: Setup.With(asResolutionCall: true),
ifAlreadyRegistered: IfAlreadyRegistered.Replace,
serviceTypeCondition: type =>
type == typeof(IMobileServiceClient) || type == typeof(IAppMobileClient));
}
I simply add a call to that method in RegisterTypes in place of registering the types in there directly.
protected override void RegisterTypes(IContainerRegistry containerRegistry)
{
containerRegistry.GetContainer().Rules.WithoutEagerCachingSingletonForFasterAccess();
...
RegisterDatabase(containerRegistry.GetContainer());
...
}
Note also the added rule for eager caching, per dadhi.
Later on when I need to release the database in the ViewModel... I kick things off by resetting my local db variable and sending an event to App.xaml.cs
_client = null;
_eventAggregator.GetEvent<RegisterDatabaseEvent>().Publish(true);
In App.xaml.cs, I have subscribed to that event and tied it to the following method.
private void OnRegisterDatabaseEventPublished()
{
RegisterDatabase(Container.GetContainer());
_eventAggregator.GetEvent<RegisterDatabaseCompletedEvent>().Publish(register);
}
Here I just call RegisterMany again, exactly the same as I do when the app starts up. No need to unregister anything. With the setup and ifAlreadyRegistered arguments (thanks, dadhi!), DryIoC allows the object to be replaced. Then I raise an event back to the VM letting it know the database has been released.
Finally, back in the ViewModel, I'm listening for the completed event. The handler for that event updates the local copy of the object like so.
_client = ((PrismApplication)App.Current).Container.Resolve<IAppMobileClient>();
And then I can work with the new object, as needed. This is key. Without setting _client to null above and resolving it again here, I actually ended up with 2 copies of the object and calls to methods were being hit 2x.
Hope that helps someone else looking to release their Azure Mobile Apps database!
I am not sure how exactly XF handles these things.
But in DryIoc in order for service to be fully deleted or replaced it need to be registered with setup: Setup.With(asResolutionCall: true). Read here for more details: https://bitbucket.org/dadhi/dryioc/wiki/UnregisterAndResolutionCache#markdown-header-unregister-and-resolution-cache
Update
Here are two options and considerations that work in pure DryIoc and may not work XF. But it probably may help with solution.
public class Foo
{
public IBar Bar { get; private set; }
public Foo(IBar bar) { Bar = bar; }
}
public interface IBar {}
public class Bar : IBar {}
public class Bar2 : IBar { }
[Test]
public void Replace_singleton_dependency_with_asResolutionCall()
{
var c = new Container(rules => rules.WithoutEagerCachingSingletonForFasterAccess());
c.Register<Foo>();
//c.Register<Foo>(Reuse.Singleton); // !!! If the consumer of replaced dependency is singleton, it won't work
// cause the consumer singleton should be replaced too
c.Register<IBar, Bar>(Reuse.Singleton,
setup: Setup.With(asResolutionCall: true)); // required
var foo = c.Resolve<Foo>();
Assert.IsInstanceOf<Bar>(foo.Bar);
c.Register<IBar, Bar2>(Reuse.Singleton,
setup: Setup.With(asResolutionCall: true), // required
ifAlreadyRegistered: IfAlreadyRegistered.Replace); // required
var foo2 = c.Resolve<Foo>();
Assert.IsInstanceOf<Bar2>(foo2.Bar);
}
[Test]
public void Replace_singleton_dependency_with_UseInstance()
{
var c = new Container();
c.Register<Foo>();
//c.Register<Foo>(Reuse.Singleton); // !!! If the consumer of replaced dependency is singleton, it won't work
// cause the consumer singleton should be replaced too
c.UseInstance<IBar>(new Bar());
var foo = c.Resolve<Foo>();
Assert.IsInstanceOf<Bar>(foo.Bar);
c.UseInstance<IBar>(new Bar2());
var foo2 = c.Resolve<Foo>();
Assert.IsInstanceOf<Bar2>(foo2.Bar);
}
I'm quite new to the Microservice world and particularly vertX. I want my verticle to start anyway even there is no database connection available (e.g. database URL missing in configuration). I already managed to do this and my verticle is starting.
The issue now is that I want my verticle to notice when the database connection is available again and connect to it. How can I do this ?
I thought about creating another Verticle "DatabaseVerticle.java" which would send the current DB config on the event bus and my initial verticle would consume this message and check whether the config info is consistent (reply with success) or still missing some data (reply with fail and make the DatabaseVerticle check again).
This might work (and might not) but does not seem to be the optimal solution for me.
I'd be very glad if someone could suggest a better solution. Thank you !
For your use case, I'd recommend to use the vertx-config. In particular, have a look at the Listening to configuration changes section of the Vert.x Config documentation.
You could create a config retriever and set a handler for changes:
ConfigRetrieverOptions options = new ConfigRetrieverOptions()
.setScanPeriod(2000)
.addStore(myConfigStore);
ConfigRetriever retriever = ConfigRetriever.create(vertx, options);
retriever.getConfig(json -> {
// If DB config available, start the DB client
// Otherwise set a "dbStarted" variable to false
});
retriever.listen(change -> {
// If "dbStarted" is still set to false
// Check the config and start the DB client if possible
// Set "dbStarted" to true when done
});
The ideal way would be some other service telling your service about database connection. Either through event bus or HTTP, what you can do is when someone tries to access your database when connection is not made just try to make some DB call and handle the exception, return a boolean as false. Now when you get a message on event bus, consume it and save it in some config pojo. Now when someone tries to access your database, look for config and if available make a connection.
Your consumer:
public void start(){
EventBus eb = vertx.eventBus();
eb.consumer("database", message -> {
config.setConfig(message.body());
});
}
Your db client(Mongo for this eg):
public class MongoService{
private MongoClient client;
public boolean isAvailable = false;
MongoService(Vertx vertx){
if(config().getString("connection")){
client = MongoClient.createShared(vertx, config().getString("connection"));
isAvailable = true;
}
}
}
Not everything in Vertx should be solved by another verticle.
In this case, you can use .periodic()
http://vertx.io/docs/vertx-core/java/#_don_t_call_us_we_ll_call_you
I assume you have some function that checks the DB for the first time.
Let's call it checkDB()
class PeriodicVerticle extends AbstractVerticle {
private Long timerId;
#Override
public void start() {
System.out.println("Started");
// Should be called each time DB goes offline
final Long timerId = this.vertx.setPeriodic(1000, (l) -> {
final boolean result = checkDB();
// Set some variable telling verticle that DB is back online
if (result) {
cancelTimer();
}
});
setTimerId(timerId);
}
private void cancelTimer() {
System.out.println("Cancelling");
getVertx().cancelTimer(this.timerId);
}
private void setTimerId(final Long timerId) {
this.timerId = timerId;
}
}
Here I play a bit with timerId, since we cannot pass it to cancelTimer() right away. But otherwise, it's quite simple.
Now I am using Gluon plugin and it is very helpful to start working with JavaFXPorts. I have my application ready and I can use it on computers and phones. I tested on phone with system android. Application is working good but only with my server.
I take care of the different resolutions and I think that it is good for now.
I want to have Turn-based Multiplayer Application but I have still big problem with using Google Play Service. Tutorial which show how to use this services for turn-based multiplayer application is written in pure android and use Activity. My question is maybe very simple but If I have my application view from "fxml" how to use it as an tutorial Activity?
I want to do auto-matching for my application and next I want override method takeTurn() to suit it to my application.
For example, how can I change thing like that (code below) to application in JavaFX?
I must use google services from my JavaFX(src/main/java folder) class in addition AndroidPlatformProvider.java and all methods must be in src/android/java folder. I know that I must use PlatformService and PlatformProvider. I did it as in the examples: HelloPlatform and SMSTracker .
I use methods from my interface PlatformProvider but application still crashes. :(
I only use Provider from my code of JavaFX and I don't have android Activity. I don't know how to use these method without Activity or View:
- public void onActivityResult(int request, int response, Intent data)
- public void playTurn(View view)
Can I call from google service methods to methods from my controller for view (fxml).
I don't know how these methods should working with JavaFX.
public class TbmpGameActivity extends Activity {
...
#Override
public void onActivityResult(int request, int response, Intent data) {
super.onActivityResult(request, response, data);
...
if (request == RC_SELECT_PLAYERS) {
if (response != Activity.RESULT_OK) {
// user canceled
return;
}
// Get the invitee list.
final ArrayList<String> invitees =
data.getStringArrayListExtra(Games.EXTRA_PLAYER_IDS);
// Get auto-match criteria.
Bundle autoMatchCriteria = null;
int minAutoMatchPlayers = data.getIntExtra(
Multiplayer.EXTRA_MIN_AUTOMATCH_PLAYERS, 0);
int maxAutoMatchPlayers = data.getIntExtra(
Multiplayer.EXTRA_MAX_AUTOMATCH_PLAYERS, 0);
if (minAutoMatchPlayers > 0) {
autoMatchCriteria = RoomConfig.createAutoMatchCriteria(
minAutoMatchPlayers, maxAutoMatchPlayers, 0);
} else {
autoMatchCriteria = null;
}
TurnBasedMatchConfig tbmc = TurnBasedMatchConfig.builder()
.addInvitedPlayers(invitees)
.setAutoMatchCriteria(autoMatchCriteria)
.build();
// Create and start the match.
Games.TurnBasedMultiplayer
.createMatch(mGoogleApiClient, tbmc)
.setResultCallback(new MatchInitiatedCallback());
}
}
}
or something like that:
// Call this method when a player has completed his turn and wants to
// go onto the next player, which may be himself.
public void playTurn(View view) {
// Get the next participant in the game-defined way, possibly round-robin.
String nextParticipantId = getNextParticipantId();
// Get the updated state. In this example, we simply retrieve a
// text string from the view. In your game, there may be more
// complicated state.
mTurnData = mDataView.getText().toString();
// At this point, you might want to show a waiting dialog so that
// the current player does not try to submit turn actions twice.
showSpinner();
// Invoke the next turn. We are converting our data to a byte array.
Games.TurnBasedMultiplayer
.takeTurn(mGoogleApiClient, mMatch.getMatchId(),
mTurnData.getBytes(Charset.forName("UTF-16")),
nextParticipantId)
.setResultCallback(this);
}
Latest version of the jfxmobile plugin (1.0.3) includes recent changes in Dalvik SDK that contains the port of JavaFX 8 to android.
In FXActivity class, it has been added a very convenient method to listen to results of intents: setOnActivityResultHandler().
This means you shouldn't add new activities to your app, and only use FXActivity. You should add an Intent to it, and set a proper result handler to the FXActivity.
Have a look at this recent post at Gluon's site. It explains how to access native services, based on the case of taking a picture with the device's camera, and waiting to get the result of it to resume the app.
Basically, this is what it is required in this case:
public void takePicture() {
// create intent
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
...
// Add result handler
FXActivity.getInstance().setOnActivityResultHandler((requestCode, resultCode, data) -> {
if (requestCode == TAKE_PICTURE && resultCode == RESULT_OK) {
...
}
});
// launch activity
FXActivity.getInstance().startActivityForResult(intent, TAKE_PICTURE);
}
Try this approach with your app.
I got some operations in my Controller class which could take some time. So I want to show a loading dialog while this operation is running.
I tried this:
Platform.runLater(new Runnable() {
#Override
public void run() {
loadingDialog.show();
}
});
Boolean opSuccess = myService.operate();
Platform.runLater(new Runnable() {
#Override
public void run() {
loadingDialog.hide();
}
});
if (opSuccess) {
// continue
}
Now, the Problem is, the loadingDialog is never show. The UI only blocks for some time and than continues on "//continue".
So it seems, the runLater call is blocked by the blocking operation (operate)?
I also tried CoundDownLatch, to wait for loadingDialog.show() to complete, before running myService.operate(). But the latch.await() method never completes.
So my question is, how my I show the loadingDialog until myService.operate() finished and returned true or false? Do I have to put the operate() call into another thread and run it async or is there an easier way?
Thanks for help.
Are you sure your entire code does not run in the JavaFX Thread?
Methods of your controller class usually do and I assume it due to your description.
However, better use the Task class. Here you'll find a tutorial and a short snippet for your application:
// here runs the JavaFX thread
// Boolean as generic parameter since you want to return it
Task<Boolean> task = new Task<Boolean>() {
#Override public Boolean call() {
// do your operation in here
return myService.operate();
}
};
task.setOnRunning((e) -> loadingDialog.show());
task.setOnSucceeded((e) -> {
loadingDialog.hide();
Boolean returnValue = task.get();
// process return value again in JavaFX thread
});
task.setOnFailed((e) -> {
// eventual error handling by catching exceptions from task.get()
});
new Thread(task).start();
I assumed Java 8 and the possibility to use Lambda expressions. Of course it is possible without them.
You are better off making use of concurrency mechanisms/Worker interfaces in JavaFx - Tasks and services instead of using Platform.runLater(). The tasks and services allow you to manage the long running tasks in a separate thread. They also provide callbacks to indicate the progress of the tasks.
You could explore further at http://docs.oracle.com/javafx/2/threads/jfxpub-threads.htm
Also have a look at the Ensemble JavaFX samples for Tasks and Services - http://www.oracle.com/technetwork/java/javase/overview/javafx-samples-2158687.html
I have developed and released one application in market long ago. Now some some users pointed crashes when holding application for long time. Now I identified the reason for the crash, that is I am using a class with static variable and methods to store data (getters and setters). Now I want to replace the static way with any other ways.From my study I got the following suggestions:
shared preferences: I have to store more than 40 variable (strings, int and json arrays and objects), So I think using shared preferences is not a good idea.
SQLite: more than 40 fields are there and I don't need to keep more than one value at a time.I am getting values for fields from different activities. I mean name from one activity , age from another activity, etc So using SQLite also not a good Idea I think.
Application classes: Now I am thinking about using application classes to store these data. Will it loss the data like static variable after hold the app for long time?
Now I replace the static variable with application class . Please let me know that application data also became null after long time?
It may useful to somebody.
Even though I didn't get a solution for my problem, I got the reason for why shouldn't we use application objects to hold the data. Please check the below link
Don't use application object to store data
Normally if you have to keep something in case your Activity gets destroyed you save all these things in onSaveInstanceState and restore them in onCreate or in onRestoreInstanceState
public class MyActivity extends Activity {
int myVariable;
final String ARG_MY_VAR="myvar";
public void onCreate(Bundle savedState) {
if(savedState != null {
myVariable = savedState.getInt(ARG_MY_VAR);
} else {
myVariable = someDefaultValue;
}
public void onSaveInstanceState(Bundle outState) {
outState.putInt(ARG_MY_VAR, myVariable);
super.onSaveInstanceState(outState);
}
}
Here if Android OS destroys your Activity onSaveInstanceState will be called and your important variable will be saved. Then when the user returns to your app again Android OS restores the activity and your variable will be correctly initialized
This does not happen when you call finish() yourself though, it happens only when Android destroys your activity for some reasons (which is quite likely to happen anytime while your app is in background).
First you should overwrite the onSaveInstanceState and onRestoreInstanceState methods in you activity:
#Override
protected void onSaveInstanceState (Bundle outState){
outState.putString("myVariable", myVariable);
// Store all you data inside the bundle
}
#Override
protected void onRestoreInstanceState (Bundle savedInstanceState){
if(savedInstanceState != null){
myVariable = savedInstanceState.getString("myVariable");
// Restore all the variables
}
}
May be try use static variable inside Application space?
public class YourApplication extends Application
{
private static ApplicationBubblick singleton;
public String str;
public static YourApplication getInstance()
{
return singleton;
}
}
And use variable via:
YourApplication.getInstance().str = ...; // set variable
... = YourApplication.getInstance().str; // get variable
This variable will be live until your app will start and stop all services or activities of your app. This is not work when your app crash.