OnResume is a method in the Android SDK (software development kit) used to resume an Activity (Android application). When an Activity is resumed, it means that it has returned to the foreground and has resumed its interactions with the user (i. e.
, it is visible and active on the screen).
When onResume() is called, the system will have already made the Activity visible to the user (which usually occurs when the Activity’s onCreate() or onStart() method is called), so the Activity should now perform any initialization or operations that are necessary in order to continue interacting with the user.
This typically includes restoring any Activity state (e. g. data, text, widgets, layout, input) that may have been changed since onPause(), and registering for user input (e. g. sensors, audio input, etc. ).
It is important for applications to respond quickly when the onResume() method is called. The Activity should perform all necessary operations in a timely manner so that the user can quickly and smoothly transition back into using the app.
As such, it should not perform any long-running tasks or operations that require a large amount of time in onResume(), as this may lead to jank or lag.
When onResume method is called?
The onResume() method is a callback that is triggered when an Activity is resumed, or when the user returns to the Activity after leaving it. When onResume() is called, it means that the Activity is now active and visible to the user, so it is the proper time to initiate any UI or data updates that are needed.
During onResume(), you can also bind any receivers and register listeners to respond to events. It’s important to remember that when the activity is resumed, any changes made by the Activity while stopped may be lost.
This includes changes to data, UI, and other resources, so you may need to re-initialize them during onResume(). It’s also important to ensure that any received content is up-to-date by refreshing data during onResume().
Generally speaking, onResume() should be used to make sure that any necessary UI and data updates are done, and to register any necessary listeners and receivers.
What is difference between onStart and onResume?
The onStart() and onResume() methods are both lifecycle callback methods in the Android Activity class. The main difference between these two methods is when they are called in the Activity lifecycle.
onStart is called when the Activity becomes visible to the user and is the counterpart to the onStop() method. It is called after the onCreate() method and before the onResume() method. While the specific tasks needed during the onStart() will vary by application, this is typically used to make final preparations before the user interacts with the Activity, such as registering broadcast receivers for receiving system messages, retrieving and displaying data from a content provider, and preparing system services like location tracking.
onResume is called after the onStart() method and when the Activity is in the foreground and the user can interact with it. This is the ideal place to start any logic that should run while the user interacts with the Activity.
This typically includes tasks like restoring input data from user preferences, refreshing data from a network connection, or re-connecting to resources that were disconnected during the onPause() method.
This is also the ideal place to start animation, video and audio playback, or any other foreground logic that should occur while the user interacts with the Activity.
The onResume method is critical because it ensures that the Activity is ready and responsive to user interactions. There are few components or operations that should begin before the onResume() is called.
Why do we need to call SetContentView () in onCreate () of activity class?
SetContentView () is a method of the Activity class used to set the xml layout to show on the screen. It is usually called in the onCreate () method of the activity class, which is the main entry point of the activity.
It is important to call the SetContentView () method in onCreate () because it helps initialize the user interface, inflate the view hierarchy, and instigate the interaction with the user or respond to user interaction.
Moreover, the resource ID is identified by the SetContentView () method which helps in locating views and components that are used in the application. As a result, without the call to SetContentView (), the activity will not have any UI and the app will not function accordingly.
What does finish () do in Android?
The finish() method in Android is used to close an Activity and remove it from the Activity stack. When this method is called, the Activity no longer exists and its lifecycle comes to an end. The finish() method can be used to end the activity and go back to the previous activity on the activity stack, creating a navigation-like experience for the user.
The finish() method can also be used to finish an application, for example to close the app when the user presses the back button on their device. Additionally, the finish() method can be used to terminate an application after a specific task is completed or to terminate the application when an error occurs.
What is onSaveInstanceState () and onRestoreInstanceState () in activity?
The onSaveInstanceState() and onRestoreInstanceState() methods of the Activity class are vital components of the Activity lifecycle. Both of these methods are used to save the state of an activity and restore it when the activity is recreated after previously being destroyed by the system such as when a device orientation changes, a new window placement is applied or the user switches back to the activity.
The onSaveInstanceState() method is used to save the current state of the activity to a bundle, allowing it to be accessed as needed in the future. This bundle can contain simple pieces of data such as strings, ints and booleans.
On the other hand, the onRestoreInstanceState() method is triggered when the activity is recreated and can be used to restore the state of the activity. It is up to the developer to decide which values from the bundle should be restored to their initial state and how the activity should look after being restored.
Big care should be taken when implementing these two methods. If done incorrectly, chances to get errors and unexpected results during restore may occur. It is also important to note that onSaveInstanceState() is called before the Activity is destroyed while onRestoreInstanceState() is called after the Activity is restored.
This means that onRestoreInstanceState() is where the values stored in onSaveInstanceState() can be retrieved and used to restore the view and state.
Why @override is used in Android?
@override is an annotation in Android which signifies that a class member (method, field, etc. ) has been overridden from its superclass or interface. This means that the superclass or interface item has been redefined and given new functionality in the current class.
The @override annotation comes in handy when you need to view and track changes which have been made to a particular item, to easily avoid undesired behavior and conflicts. It helps to ensure that the correct class method, field, etc.
have been used and also provides a specific level of security as it is enforced by the Java Compiler. This annotation also helps to increase code readability across all classes in your project, making the project itself much easier to manage.
What happens when you call finish () inside onCreate ()?
If finish() is called inside the onCreate() method of an Activity, then it ends the activity as soon as the onCreate() method is executed. This means that the activity will immediately be destroyed when the onCreate() method returns, and any code after the finish() instruction will not be executed.
It also means that the onResume(), onPause() and onStop() methods will also not be called in this case, because they cannot be called when the activity has already been destroyed. Calling finish() inside onCreate() is typically done in order to terminate an activity if certain conditions are not met.
For example, if the user is not logged in, the activity can be finished immediately in the onCreate() method.
Does finish call onPause?
No, the finish() call does not call onPause(). finish() will terminate an Activity without taking the lifecycle into consideration. This can lead to issues related to the Activity’s state, because the Activity’s onPause() and onStop() methods will not be called.
It is much better to use the Activity’s finish() method to invoke the normal sequence of lifecycle methods, which includes onPause() and onStop().
How do you close out apps on an Android?
On an Android device, you can close out apps by following these steps:
1. Open the Overview Screen: You can open the Overview Screen by pressing the recent apps button located on the bottom left corner of the device’s navigation bar. You can also access the Overview Screen by swiping up from the middle of the device’s home screen.
2. Select the app to be closed: On the Overview Screen, you will see all the apps that are currently opened. Swipe to the left or right to view all the apps. Select the app you want to close by tapping on its thumbnail.
3. Swipe up on the app: Swipe up on the thumbnail of the app you selected. This will close the app and remove it from the Overview screen.
4. Exit the Overview Screen: To exit the Overview screen, either press the Back button located at the bottom left of the device’s navigation bar or press the home button located at the bottom center of the device’s navigation bar.
What is onPause () meant for?
OnPause() is a lifecycle method for the Android Activity class. It is called when an activity is about to go into the background (e. g. if the user presses the HOME button), and it is used to free up resources and stop any animations, running threads, and other ongoing activities.
Any long-running operations that the activity needs to perform should be done in the onPause() method so that the activity can be resumed without needing to restart any of these operations. The onPause() method also allows the activity to save its current state (e. g.
the current instance of a UI element) so that it can be restored when the activity is resumed later.
Which is called first onStart or onCreate?
OnCreate is called first when an Activity is launched. OnCreate is an abstract method that is part of the Activity lifecycle and is responsible for doing the initial setup of the Activity. It is where you should do all of your normal static set up such as create views, bind data to lists, etc.
After OnCreate is finished, the Activity’s onStart method is called. OnStart is the first point in the Activity lifecycle is where the user can see the Activity on the screen. After OnStart is complete, the Activity will become visible and OnResume will be called.
OnResume is the most important of these three methods and marks the beginning of the Activity being interactive with the user.
Why is onResume called after onCreate?
The onResume() event is called after onCreate() event because onResume() is triggered whenever the activity returns to the foreground or the user interacts with the activity. For example, after the user presses the home button, the activity will be stopped and onPause() will be invoked.
After that, when the user returns to the activity, onResume() will be called.
Additionally, onResume() is also called when an activity is created for the first time. This is because during the process of creating the activity, its life-cycle events are called from onCreate() to onResume().
Thus, onResume() is called after onCreate() because it needs to be invoked in order to get the activity visible and responsive to user interaction.
What comes after onCreate?
The next step after onCreate is typically the onStart() method. This is where the application code can start interacting with the user, such as by setting up the initial user interface layout. The onStart() method is typically used to do initialization work, such as setting up the initial user interface or launching a background service.
After onStart() finishes, the onResume() method is typically called. This is when the app is ready for the user to begin interacting with it, such as viewing its contents or inputting data. After onResume() is finished, the app is then in an active state and can respond to user input.
Depending on the user action, other life-cycle methods such as onPause(), onStop(), onDestroy(), and onRestart() can be called. It is important to understand the order of these life-cycle methods, so that the application can respond properly to different user events.
What is super onCreate savedInstanceState?
super. onCreate(savedInstanceState) is a method that gets called when an Activity is created in Android. This method overrides the onCreate method in the parent class and is a way to access the parent class’ onCreate method and execute the code inside of it.
It is typically used to restore saved state information of the Activity, such as user preferences or UI state, as well as any data that the Activity needs to pass between activities. This is done via the savedInstanceState parameter, which is a Bundle, or a collection of data that is stored in memory and can be accessed anywhere in the App.
The Bundle is typically populated by the Activity’s onSaveInstanceState method, which is called when the Activity is about to be destroyed. super. onCreate(savedInstanceState) is an important step in developing an Android Activity, and it should always be used when creating an Activity in Android.
