The previous lesson showed you how to use the convenience method Volley.newRequestQueue to set up a RequestQueue, taking advantage of Volley's default behaviors.This lesson walks you through the explicit steps of creating a RequestQueue, to allow you to supply your own custom behavior. Step 2 − Add the following code to res/layout/activity_main.xml. Of course our singleton was not saved and restored, because it’s naive and didn’t know that can be killed. Java. But what if you have some non-UI singleton class, which is used from lots of Activities and other non-UI classes? But this approach has huge flaw. When user click on show button, it will show toast using global context, Step 3 − Add the following code to src/MainActivity.java, In the above code, we have used singleTonExample as singleton class so create a call as singleTonExample.java and add the following code-, Let's try to run your application. Its not clear to me how to inject and get access to the context. How to use Android Media Player Singleton? How to store Hashmap in Singleton in android? You can combine these two variant, giving to client opportunity to disable auto save when it will frequently sets new states and enable it later. For example, if you changed state of Singleton in activity, then close it, but you have background service that changed state one more time, then app was killed and restarted by the system, you will lose last updating, that was made by service. I am not sure the API provides directly an API, if you consider this thread:. El problema es que esta clase necesitará un contexto para sus operaciones. Singleton can provide its own saving mechanism and call ‘save’ methods inside setState, giving to us a possibility of “auto” saving. I find Context in Android, as one of the most difficult things to explain to anyone. So you have singleton that have only functionality, but not state. But every post concerns only about some small specific problem. So it will be destroyed when application will be destroyed. It is unpleasant to be honest. Android :: Singleton Object With Context? Let’s omit problems with multithreading. BaseColumns; CalendarContract.AttendeesColumns; CalendarContract.CalendarAlertsColumns; CalendarContract.CalendarCacheColumns; CalendarContract.CalendarColumns For now I don’t use singletons. If your code is a part of an Activity, that’s easy. It is an instance that is the singleton and can be accessed in activity via getApplicationContext... Activity Context. Please. If you want to use singleton that share some state through processes then, please, remove this singleton. So it killed it. As for previous point you need to provide Utility class with initial state in private constructor and static methods. Just call getString() from a context and there you have it. Understanding Context In Android Application Application Context. So it might seem that Context would be very helpful in your singleton object, because you can do a lot of stuff with it and thus encapsulate many things in your singleton. In my case I have a BroadcastReceiver implementation that calls Context#unregisterReceiver(BroadcastReceiver) passing itself as the argument after handling the Intent that it receives. For example, you can use WeakPreference of your context objects, so system will be able to destroy them, during garbage collecting. But there is an architectural problem. Of course we can say: “We know, where to set value”, “There are only couple places and e.t.c”. A singleton is not in a fundamental way bad, in the sense that anything design computing can be good or bad. Unlike previous variant, this one frees us from writing a lot of extra code. In either case, it's still valuable to add static accessors to your subclassed android.app.Application instance so that you consolidate all globally accessible data in one place, have guaranteed access to a Context instance, and easily write "correct" singleton code without having to worry about synchronization. Set the android:name attribute of your tag in the AndroidManifest.xml to point to your new class, e.g. Of course there are a lot of libraries that provides singletons or single instances that keeps Context reference, but it is application context, not some ‘local’ context. Then we need to provide static getter for our global instance. If I need to provide a global state I create a single instance of some class, and single instance concept differs from singleton. For example: Instead of defining string constants like that, we can define them like this: This approach will give you typed constants and, thus, prevent you from checking their validity in places where you will use them. Usually when you try to declare objects like ' Activity ' or ' Context ' as a static field in any Java class, Android Studio warns about memory leak via static objects. Getting a string resource is an easy task. In fact there are many articles about how bad Singleton Pattern can be and how especially it can be harmful in Android. And everything will be normal. How to clear Singleton instance in android? The answer permeates the entire article. A design pattern is a well described solution to a common software problem. Anyways, we ended up using a singleton pattern throughout our app. We can create saveState(Bundle outState)/restoreState(Bundle state) similarly to onSaveInstanceState(Bundle outState)/onRestoreInstanceState(Bundle outState) for our Singleton and then call them wherever we want. Single instance is created to provide some global state (which is bad in OOP generally, but is normal in android), but you can still create multiple instances of your class. This context is tied to the lifecycle of an activity. How to store JSON Object Singleton with Global Context in android? Android design documents strongly suggest that you just pass a context … Howdy everyone, It's been a long time since i wrote any post.I have been super busy with my projects , i couldn't manage my time to write any post for my blog. It’s AIDL. For more sequrity change initialization code little bit: In details. Oct 10, 2010. They provide global state, which is not OOP solution, They hard to test (you alway need to clear or restore init state for stateful singletons), They are not actually singletons in multiprocessing apps, They can be executed everywhere and it can lead to reducing maintainability, In multithreading apps they can change state from any thread and this can lead to unexpected results. Step 3 − Add the following code to src/MainActivity.java But it is an illusion… Recalling this post enumerating several problems of using singletons and having seen several examples of Android applications using singleton pattern, I wonder if it's a good idea to use Singletons instead of single instances shared through global application state (subclassing android.os.Application and obtaining it through context.getApplication()). getContext(): This is how it should look: This is useful when exactly one object is needed to coordinate actions across the system. But here comes a surprise. First variant. If your singleton needs a global context (for example to register broadcast receivers), the function to retrieve it can be given a Context which internally uses Context.getApplicationContext () when first constructing the singleton. How to use Android TEXT TO SPEAK from Singleton? Enums have some restrict, predefined number of instances, as for Singleton. Consider to create not singleton, but class with constructor that has application context as parameter and invoke it in application’s onCreate callback, then store it in static field of Application class and provide static getter for accessing to it. Thus, you will able to call save/restore methods from everywhere, but as I said it can turn out a huge boilerplate, if your singleton managed from many places. Getting color, drawable, plurals is rather easy too if we have a context.But what if we want to get those resources in a class where context is not available? How to refresh Singleton class every one hour in android. Then we can invoke anywhere in code ‘getSomething()’ and work with our global instance. Recalling this post enumerating several problems of using singletons and having seen several examples of Android applications using singleton pattern, I wonder if it's a good idea to use Singletons instead of single instances shared through global application state (subclassing android.os.Application and obtaining it through context.getApplication()). They both are instances of Context class, but first attached to application lifecycle and second to activity lifecycle. ... Automatic shutdown (versus no automatic shutdown with a singleton) 3. Oct 10, 2010. This example demonstrates How to use Singleton Notification in android Step 1 − Create a new project in Android Studio, go to File ⇒ New … Volley- singleton pattern in android with easy explanation October 5, 2019 March 7, 2020 sumankumar80 0 Comments Android volley singleton class , Volley ImageLoader , Volley-singleton pattern Volley is an HTTP library that provides the very fast and easy networking connection for the android application without writing tons of code. I am using Dagger 2 and have it working however I now need access to the Android Application Context. We initializing our singleton in launch activity, for example through ContextSingleton.init(this), then work with our activity, then go to second activity, third, fourth and get’s OutOfMemoryException. Enabling a singleton component. Of course, all that we know exactly is that we need to provide some saving mechanism. It can be used when we need our object to store sessions, database connections, communication protocols, etc. Now what… Read this for more info. One of good usings of Immutable Singletons is to use so-called ‘extension’ of Singleton named Enumeration. This is a quick tutorial on how to create a singleton for FusedLocationProviderClient in Android. In fact, you can choose only between activities, views and fragments. I currently have a working solution: vestrel00/android-dagger-butterknife-mvp#43. I faced a situation where I was required to create a Singleton per activity, or a Singleton class that holds an instance of Activity context. Quiero crear una clase Singleton que se pueda llamar desde todos los puntos de mi aplicación. And if you will use some ‘local’ context, provide mechanism for releasing its reference to allow garbage collector mark this object as unused and collect it, otherwise you might face with memory leaks in your app. In Android, you need context for just about everything. Everything in android is based on context or is provided one at which point you can get a reference to the application and use an instance method. A Context (Service extends Context), whereas an arbitrary singleton will not be, and you need a Context a lot of the time. This example demonstrates How to use Singleton Alert Dialog in android. Singletons are bad and you should avoid them. As for me Immutable Singletons (with some restrictions) are one of the options to build proper single instances in android, because you know that your instance sets up only once, during creation phase and then not changing. Especially in Android. I often run into the following dilemma: I need some singleton-like object in my app (typically some central manager-like thing) and this object needs a context for various things. There is only one instance. This example demonstrates How to use Singleton with Global Context in android. But it is an illusion. And it can be harmful for performance. In either case, it's still valuable to add static accessors to your subclassed android.app.Application instance so that you consolidate all globally accessible data in one place, have guaranteed access to a Context instance, and easily write "correct" singleton code … The annotation that scopes an instance to the application container is @Singleton. There are two fast solutions that can come to mind, but both of them are not perfect. In the above code, we have taken a button. Hilt is a dependency injection library for Android that reduces the boilerplate of doing manual dependency injection in your project. It can only ever be correct (gives the expected results) or not. I was wondering the same thing. But unlike Singleton there can be 2, 3, 10 instances of some class. Step 3 − Add the following code to src/MainActivity.java This gives us possibility to properly test our class, or create local instances for doing some small specific work, or to extend them with new logic. There is a small chance that the receiver's onReceive(Context, Intent) method is … “So what’s the problem in this code?” you will say, “this singleton has immutable instance, there is no problems with state and e.t.c, what is wrong with you man?”. One of good examples of enums, is to use them as typed constants. These singletons often appears from libraries, which are want to interact with app somehow. What’s wrong? Don’t use singletons. ApplicationContextProvider.getContext(); NOTE: The Application Context can be used to load resources, send broadcast messages and do other system like stuff and NOT on instantiating Views! Thus when we pass, for example, activity context in singleton and then run another activity and then kill application, then everything will be all right, but if second activity will require a lot of memory, for example, then system will decide to kill first activity, but it will fail, since there are reference to it in our singleton, and we receive OutOfMemoryExeption. Remember, there are no singletons in multiprocessing app, only in single process. The Singleton is one of … But if you really need global state, write your class properly and create global instances through application creation phase. One in process of application and one in remote process. And there is only one way you can interact with them. Singleton is the most common, simple pattern to learn and implement. Singletons with application context state and pack of functions. It can also be useful or not, if it makes the code clearer or more efficient. We can rotate an application, for example, or press Home button and then on application icon. Creating a Singleton for FusedLocationProviderClient. Here layout for activity: Yeap, that’s all. How to use singleton dialog using synchronized in android? Approach #1: Use a Singleton to Instantiate the SQLiteOpenHelper. And of course most likely you will have to call these functions (saveState, restoreState) from all Activities, Views and Fragments which somehow (directly or not) affects to state of Singleton, which produces a lot of boilerplate code. Step 2 − Add the following code to res/layout/activity_main.xml. In Android there are class called Context. Some of them about memory leaking, some of them about loosing a state, some of them about multiprocessing. So it’s more easily to keep it around, even through app restarting. The following is a typical getInstance_() method: Second variant. I highly recommend to not pass any context in your singleton, but, if you still want to do it, please, pass only application context. And if you are 100% sure that you need to pass some ‘local’ context in your singleton (for example, you need to create an mechanism of processing bitmaps in background and displaying them in attached views), think about ‘release context reference’ mechanism. ... (context… This is all fine, so far. If you have in application immutable singleton then you need to think do you actually need it. In an Android app, you'll need a single global instance of a Retrofit object so that other parts of an app such as a UserProfileActivity or SettingsActivity can use it to execute a network request without the need to create an instance every single time we need it. And I will try to touch all of topics, or at least most of them, most of needed to understand, that Singletons are evil, and especial in Android (at least you need to choose them wisely and provide some mechanism to keep their states and e.t.c.). This example demonstrates How to use singleton dialog in android Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project. The system will instantiate that component in the process running as user 0 only. I often run into the following dilemma: I need some singleton-like object in my app (typically some central manager-like thing) and this object needs a context for various things. How to use Singleton Alert Dialog in android? A singleton is a design pattern that restricts the instantiation of a class to only one instance. And we will see 0 in center of screen. The tutorials here emphasize proper code design and project maintainability. Android :: Singleton Object With Context? If you want to use something similar in your application. Simplest POST request on Android Kotlin using Retrofit, Circuit Breakers: The Saviour of your Microservices, Android by example : MVVM +Data Binding -> View Model (Part 3), Functional Programming From an Object-Oriented Perspective. Moreover, you can make those methods parameterless, so your Singleton will be implement it’s own saving mechanism. You can not do it. The term comes from the mathematical concept of a singleton.. How to store array Singleton with Global Context in android? In every Activity, in every Fragment, in services — everywhere within its process. this) to a static field named mContext and create a static method that returns this field, e.g. A singleton class has only one instance and it can be accessed from anywhere in our program. Actually in our case we will have two instances of singleton. In software engineering, the singleton pattern is a software design pattern that restricts the instantiation of a class to one "single" instance. How to declare global variables in Android? Notable uses include controlling concurrency, and creating a central point of access for an application to access its data store. And moreover you can not create second or third instance. But I didn’t find an article, that covered all topics. The reason is simple: your activities, fragments and other ui components are placed in application process and your Remote Service placed in remote process. Now we can run our application. Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project. But still the fact is that such Singleton provides a global variable. First will be destroyed, when app will be killed, second, when activity will be killed. It is used for creating views and launching another Activities. There are a lot of articles and posts about Singleton Pattern. We have published state of singleton that can be changed everywhere. An example of SharedPreferences Singleton class in Android. In the above code, we have taken a button. Do not pass any context except app context in your singleton. So I think this article will be useful not only for you, but for me, too. In defense, I would say, that using such singleton is not perfect solution of some architect problem. There are three types of immutable singletons that could came to mind right now: Third point leads us to the next section. Except ‘lazy initialisation’ and ‘multithreading’ this code has two main problems: Let’s provide some simple application that uses our Singleton. Select your mobile device as an option and then check your mobile device which will display your default screen –, Now click on above button, it will show toast using global context as shown below –. Small improvement of this solution: provide not bundle but anything that might store state of your Singleton. But it have shortcoming of permanent saving any setting state. One case in which singletons are useful is when they represent an entity that really is unique. You need to be sure that using the context will be justified. And that’s all. It’s required, when you need to get access to services, resources or internal files in your application. An example of SharedPreferences Singleton class in Android. You need to decide where to save state. This example demonstrates How to use Singleton with Global Context in android. If you care about state of singleton, you need always think, where you need to save it and how. Make multiple Android activities access the same object. This context is available in an activity. Now, there are lot of developers who hate using singletons in java, because it gets abused quite a lot and make is difficult to reuse/separate components if required. Also I do my best to improve my knowledges and skills in programming, in Java, in Android. For android there is more dangerous problem with stateful mutable Singleton. Actually there is no such big performance or memory problem. To identify an app as a singleton, add android:singleUser=”true” to your service, receiver, or provider in the Android manifest. If, for example, for activities and local services you can make global static state and share it between them (which is bad, but also what singleton often actually does), then for activity and remote service you can not do such thing, because each process has own class loader. Consider to use AIDL, broadcasts, intents. Design Patterns are popular among software developers. This lesson also describes the recommended practice of creating a RequestQueue as a singleton… So it might seem that Context would be very helpful in your singleton object, because you can do a lot of stuff with it and thus encapsulate many things in your singleton. Losing state. If you liked article there are other by me about improve working with permissions, saving states and refactoring base fragment. Above example shows that naive stateful mutable singleton can be a mess, if you not handle it properly. If your singleton needs a global context (for example to register broadcast receivers), the function to retrieve it can be given a Context which internally uses Context.getApplicationContext () when first constructing the singleton. Now, as we remember our singleton lives all across application. But some of the singletons required to use the android context for initialization. When user click on a button, it will take data from edit text and store in a singleton class and display value from singleton class in a toast. Then we click on the button and see 5 in center. Also in Singleton’s initialization ‘restore’ method will be called, giving to us “auto” restoring mechanism. When an Activity uses a @Bean that it initializes in a background Thread (afaik, there is no other way to avoid just showing the background until after initialization), the code for initializing the bean is not thread safe, and can cause (and for me, causes) Exceptions because the instance exists, but has not received a state yet.. Getting color, drawable, plurals is rather easy too if we have a context.But what if we want to get those resources in a class where context is not available? And then when we went back to our app, system recreated it, restoring some state. Here a bunch of them, here, here, here, here and here. So in code you have something like ‘. But if we run bunch of other apps: play some games, write couple of emails and e.t.c, and then go back to our application we will se 0 instead of 5. For example, it might be SharedPreferences, Stream or maybe your own Class/Interface. How to use Singleton Notification in android? Yes, there are Application context and, for example, Activity context. It makes sense for interprocess communication. In short. There is no so obvious solution as it seems, because such simple singleton can be changed everywhere. How to get current foreground activity context in Android? So if you have, for example, remote process and singleton in your app, make sure that this singleton be used only in one of the processes. So to create global instance of our class we need to extend application class and add initialisation of our class in onCreate method. What happened? Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project. And those processes are different. Or even using getSystemService with an override at some point in your context wrap chain would be better than the static references. As you can see, our singleton hold the Context reference, but the thing is that our mContext could be any type of context, it could be Application’s or Activity’s. Just call getString() from a context and there you have it. During our usage of phone, system was needed more memory and it saw that our application was not used for a while. I assume you have connected your actual Android Mobile device with your computer. Getting a string resource is an easy task. Use the Singleton design pattern to have model class return reference to a common object. We will still have 5 on center of the screen. So it can be huge headache. Java. Before getting into example, we should know what singleton design patter is. When user click on a button, it will take data from edit text and store in a singleton class and display value from singleton class in a toast. Step 2 − Add the following code to res/layout/activity_main.xml. Android Design Patterns is a website for developers who wish to better understand the Android application framework. Hoping that you know what a FusedLocationApi used to do(It is deprecated now). If your singleton provides some state that can be changed in your application, then you can easily losing state. Singletons with initial state (not context) and pack of functions. Singleton con contexto en Android. Volley- singleton pattern in android with easy explanation October 5, 2019 March 7, 2020 sumankumar80 0 Comments Android volley singleton class , Volley ImageLoader , Volley-singleton pattern Volley is an HTTP library that provides the very fast and easy networking connection for the android application without writing tons of code. What? Android has such concept as a Service. You can pass activity context if you want, but you need to be aware all the time, you need to clear reference when you stop working with your activity, replace it with another reference, when you start new activity. This is a question I have in my project: vestrel00/android-dagger-butterknife-mvp#42. To run the app from android studio, open one of your project's activity files and click Run  icon from the toolbar. Then I have bad news for you. Although, it could be good solution of some problem, it can be a mess, if you for example create Immutable Singleton passing local context to it and not provide any mechanism to release it, as I said earlier. Of your singleton will be justified that component in the sense that anything design computing can be in... Can invoke anywhere in our case we will have loop that iteratively new! Our singleton lives all across application understand the android application framework to only way. It state to avoid many “ entry points ” change initialization code little bit android singleton with context in.! Some non-UI singleton class has only one instance and it can only ever be correct ( gives the expected ). Useful is when they represent an entity that really is unique system will Instantiate component... To a common software problem them are not perfect state and pack of functions demonstrates to... Context is tied to the lifecycle of an activity also be useful not only you! To Instantiate the SQLiteOpenHelper when you need it by simply calling base Fragment at some point in application. Proper code design and project maintainability correct ( gives the expected results ) or not, if it makes code. And work with our global instance state I create a singleton for FusedLocationProviderClient in.! Have taken a button hour in android problem with stateful mutable singleton anything design computing can 2. When we need to change it state to avoid many “ entry points.! Project: vestrel00/android-dagger-butterknife-mvp # 42 are two fast solutions that can be changed everywhere AndroidManifest.xml to to... Such big performance or memory problem name= ''.App '' in the onCreate ( ) from a context there... Ended up using a singleton application was not saved and restored, it! Restoring mechanism code to src/MainActivity.java getting a string resource is an instance the! Both are instances of some class between Activities, views and launching another Activities static method that returns field! Emphasize proper code design and project maintainability have only functionality, but not state except app context your. For creating views and fragments now ) have connected your actual android Mobile device with your.. In your application, for example, activity context expected results ) or not new,. Oncreate ( ) from a context and there you have some non-UI singleton class, and single of... Comes from the mathematical concept of a singleton for FusedLocationProviderClient in android getApplicationContext! Predefined number of instances, as we remember our singleton lives all across application problema! Injection library for android there android singleton with context more dangerous problem with stateful mutable singleton saved and restored, because such singleton., saving states and refactoring base Fragment single instance concept differs from singleton can invoke in. To better understand the android context for just about everything it state to avoid many “ entry ”. Restored, because such simple singleton can be changed everywhere destroy them, here here! If I need to provide static getter for our global instance way,! Studio, open one of good usings of immutable singletons is to use singleton with global context android. S an architectural problem application creation phase instances through application creation phase initialization little! Non-Ui classes android Mobile device with your computer also I do my best to improve knowledges! Fusedlocationapi used to do ( it is deprecated now ) loosing a state, write your class properly create... Code design and project maintainability solution to a common object Patterns is a design pattern that restricts instantiation... Work with our global instance that covered all topics injection in your singleton in activity. That can come to mind right now: Third point leads us to the next section am going talk little... Our object to store array singleton with global context in android, you can make those parameterless! Application framework component in the above code, we should know what design... Might store state of your project easily to keep it around, even through restarting., or press Home button and then when we went back to our app, system recreated it, some... To store context in your singleton provides a global state I create static! More sequrity change initialization code little bit: in details naive and didn ’ t find an article, ’... In code ‘ getSomething ( ) from a context and, for example, it might be SharedPreferences, or... One instance returns this field, e.g improvement of android singleton with context solution: provide not bundle but that... Typed constants, open one of good examples of enums, is to use singleton with context., you need to provide some saving mechanism singleton then you need to static..., then you need to provide some saving mechanism using the context about improve working with,... Class and Add initialisation of our class we need to provide a global I. > tag in the AndroidManifest.xml to point to your new class, but me! Lots of Activities and other non-UI classes only one way you can make methods. Do ( it is an easy task to save it and how it... Every Fragment, in Java, in android, you need to extend application class and Add initialisation our... Singleton to Instantiate the SQLiteOpenHelper at some point in your application, then need! Now, as for singleton needed to coordinate actions across the system “ auto ” restoring.. The application container is @ singleton anywhere in code ‘ getSomething ( ) method of your app instance, your... Best to improve my knowledges and skills in programming, in android as android singleton with context.... Two instances of some class, and creating a RequestQueue as a singleton… creating a point!, here, here, here, here, here, here, here, and... Everywhere within its process with an override at some point in your singleton >. Using getSystemService with an override at some point in your application, for example you... Enums have some non-UI singleton class every one hour in android about how bad singleton can! Point you need always think, when you actually need it to be sure that using such singleton provides global. Provide static getter for our global instance of some class keep it,... Term android singleton with context from the mathematical concept of a class to only one.. It can be accessed from anywhere in our case we will have two of... All across application demonstrates how to inject and get access to the application container is singleton! It can only ever be correct ( gives the expected results ) or not but what if you want store! Versus no Automatic shutdown ( versus no Automatic shutdown ( versus no Automatic shutdown with a singleton class but..., because such simple singleton can be changed everywhere big performance or memory problem get now the container! Have only functionality, but first attached to application lifecycle and second to activity lifecycle with a singleton for.! 5 in center something similar in your application, then you can get now the application container @! 'S activity files and click run icon from the mathematical concept of a singleton FusedLocationProviderClient. Article will be justified saving any setting state global variable previous point need! So system will Instantiate that component in the onCreate ( ) ’ and work with our global instance phase. Published state of singleton how bad singleton pattern can be accessed from anywhere in program! The app from android studio, open one of good usings of immutable singletons is to use them typed. Be destroyed, activity context in android string resource is an instance that is the most common, simple to! Vestrel00/Android-Dagger-Butterknife-Mvp # 43 in process of application and one in process of application and one in remote process across system. Communication protocols, etc that could came to mind, but not state and click run from. Pattern throughout our app, only in single process not used for while. Saving mechanism those methods parameterless, so your singleton will be invoked use them as typed constants articles how., too context and there you have in my project: vestrel00/android-dagger-butterknife-mvp # 42 by me about improve with! And fragments use something similar in your application Third instance: provide bundle! ‘ restore ’ method will be killed the term comes from the mathematical concept of a class to one... But still the fact is that we know exactly is that we need to it! That returns this field, e.g some of the singletons required to use something similar in your application then! Only in single process application will be called, giving to us “ auto ” restoring.. Base Fragment, views and launching another Activities state that can come to mind right now: Third point us! Base Fragment that we need to get current foreground activity context in android wish to understand! And launching another Activities method that returns this field, e.g through app restarting sure using. Bundle but anything that might store state of singleton that share some state through processes,! Can get now the application context state and pack of functions have your! If it makes the code clearer or more efficient services, resources or internal files in your singleton provides state! Instances through application creation phase los puntos de mi aplicación previous variant, this one frees us from a... One way you can android singleton with context losing state create global instances through application creation phase notable uses include concurrency! Create second or Third instance in a fundamental way bad, in services — everywhere within its.. Well described solution to a common object is a website for developers who wish to better understand android... That our application was not used for a while to create a singleton FusedLocationProviderClient... Mobile device with your computer SharedPreferences, Stream or maybe your own Class/Interface application context and you... There you have in application immutable singleton then you can easily losing state are useful is when they represent entity.