onCreate savedInstanceState is a method in the Android Activity lifecycle that is called when an Activity is first created. This method can be used to restore any saved state that may have been previously stored when the activity was paused or destroyed.
The savedInstanceState object passed into the method contains a bundle of key-value pairs that represent the state of the Activity when it was last paused or destroyed. The bundle is passed into the method in order for the Activity to be able to restore the same state that it had immediately before the pause or destruction.
The onCreate savedInstanceState is a critical piece of the Activity lifecycle, as it allows users to be able to resume activity from where it left off if the activity is paused or destroyed.
What is onCreate () meant for?
onCreate() is a callback method that is part of the Android Activity lifecycle. It is responsible for initializing the activity before it is displayed to the user. It is one of the first methods that is called after the activity has been created.
The onCreate() method enables you to set up the basic activity structure that will be used for the rest of the lifecycle. The onCreate() method receives a bundle that contains the state of the activity if it were previously destroyed.
This bundle can be used to restore the activity’s state. In the onCreate() method, you should also be performing other tasks such as initializing widgets and declaring any user interface layout. Furthermore, it is in onCreate() where you should instantiate objects that are used specifically in the activity.
Is onCreate called only once?
No, onCreate is not only called once. It is an Android lifecycle method that is called when an Activity or Fragment is created. It is generally called once when the Activity or Fragment is first created, but it can also be called again when the Activity or Fragment is recreated due to a configuration change such as a screen rotation.
This can be done manually by the developer or automatically by the Android system. In any case, after it is called, the onCreate lifecycle method can run again when the Activity or Fragment is recreated, allowing for persistent state between configuration changes in the same instance.
What is an Android activity?
An Android activity is a single user interface screen or a “page” of a mobile application. It is the visual representation of an Android application and contains everything that the user needs in order to interact with the application.
Activities generally contain Views and Fragments, which are individual components of the overall user interface. Activities are typically initialized when the user navigates to a specific page in the application, and perform tasks such as displaying information, capturing user input, connecting to databases, and more.
An activity can also initialize other activities and receive results from them, allowing for a wide variety of interactions. Android activities often have a corresponding layout XML file, which defines the user interface for that particular activity.
What is the use of a bundle object?
A bundle object is a type of object used in the Android operating system to store a collection of key-value pairs. This type of object is used to pass data between different activities or to store application configuration values.
A bundle object can store primitive types such as integers and booleans, as well as non-primitive types such as strings, classes, and other bundles.
The bundle object has several advantages over other forms of data storage, such as shared preferences and databases. It is lightweight and easy to use, and unlike databases, does not require specialized programming techniques.
Bundle objects can also allow for easy data sharing between activities, since it is simple to serialize and deserialize the bundle object in order to save and restore the stored data. The stored data can also be used inside activities, making it easy to access data between different application components.
Bundles can even be used to store objects that are part of the Android API or from 3rd party libraries.
In summary, a bundle object is an efficient and useful method of storing and transferring data across application components in the Android operating system.
How do you use onCreate method?
The onCreate method is a vital component of the Android Activity Lifecycle, which is triggered when an activity is created. This method is called after onStart() and is used to initialize the activity.
It is used to instantiate the app’s user interface and any components that the activity needs to manipulate the user interface elements. It is also used to retrieve any saved data from the database, so that a view is available for the user.
In addition, it is used to register any broadcast receivers and necessary listeners that the activity might need.
Overall, the onCreate method is essential in providing the essential initialization routines to an activity, so that it can successfully interact with the user. It is used to configure the different user interface elements, display the necessary data, register the needed listeners, and perform other essential setup routines.
Without it, the activity would not be able to correctly interact with the user.
Which according to you is a better option ViewModel or savedInstanceState?
It really depends on the specifics of the application and what it is designed to accomplish. The ViewModel is best when it is used to store and manage the UI-related data, while the savedInstanceState is better for holding non-UI data.
ViewModel is especially useful for retaining data when the device is rotated or when the user is going back and forth between different activities or fragments. It is a convenient way to store data as long as the user needs, as it persists and remains valid until the activity or fragment is destroyed.
On the other hand, savedInstanceState is more useful for short-term data storage, such as when the user needs to store a certain amount of information for a short period of time, for example when the user needs to collect data from a view to be processed and saved at a later stage.
It is also good for efficiently managing small-scale data, such as when the user needs to store a small amount of data while they are navigating between activities or fragments.
Either option can be a better option depending on the specific needs of the application. Generally speaking, ViewModels are better for preserving data when the user is travelling between different views in the application, while savedInstanceState is better for more short-term data storage.
Is onCreate () The first method to be called by the Android compiler?
No, onCreate() is not the first method to be called by the Android compiler. The first method that is called by the Android compiler is the onCreate() of the Application class. This is followed by the onCreate() of the Activity subclass, which is generally where most of the initial set up for an Activity’s user interface and other features is done.
After onCreate(), the compiler will then execute a variety of lifecycle methods depending on how the user interacts with the UI, such as onStart(), onResume(), and onPause(). So, while onCreate() is an important part of the Android lifecycle and is generally the first method called by an Activity, it is not the first method to be called by the Android compiler.
Why do we override onCreate?
OnCreate() is an important callback method that is overridden when building an Android activity. It is called when the activity is first created and is responsible for setting up the activity’s user interface.
The overridden method should also be used to do important initialization tasks such as retrieving and storing UI elements (e. g. TextView, EditText etc. ), responding to user interactions, initializing the activity’s data, setting up the data adapter (for view recycling) and doing any other runtime tasks that are necessary for the activity to function correctly.
Overriding onCreate is beneficial for code reuse, readability and maintainability. Since it is a callback method, it allows developers to separate the initialization tasks from a linear flow of code.
Therefore, the same logic can be used across different activities in an app, making the code much easier to read and maintain. Additionally, onCreate is called when the activity is first created, so it allows us to set up the UI, data and other runtime-related tasks before starting the main code of the activity.
Allowing us to do this setup first helps ensure that the program runs as intended.
What is Android super?
Android Super is an advanced version of the Android operating system. This operating system is designed for device manufacturers and offers enhanced performance, security, and customization capabilities.
With this version, manufacturers can access system API, manage core functions and customize their device software. Android Super also has several lightweight memory and storage management tools. This allows device performance to be optimized and allows manufacturers to reduce cost and improve the quality of their product.
Android Super is used for tablet and smartphone devices, but is also used on smart TVs, vehicles, and even robots. This version of the Android OS is powerful and efficient and is becoming more popular among manufacturers to ensure that their devices are better equipped to handle the latest mobile technology.
What is @override in Android Studio?
@override is a Java annotation that is used to indicate that the method being called is overriding a method with the same signature from a parent or superclass. When used, the compiler will check to make sure that the method being called is actually overriding another method.
If not, it will throw an error. This helps to ensure that proper syntax and rules are followed when overriding methods. In Android Studio, @override can be used when methods are being overridden in an activity, service, or fragment.
It is especially useful when developing apps with multiple activities and services since it makes it easier to keep track of which methods are inherited from a parent class and which are overridden.
What is the purpose of using setContentView R layout Activity_main )?
The purpose of using setContentView(R. layout. activity_main) is to inflate the layout file and make its contents visible in the corresponding activity. This setContentView() method is used to set the xml layout file within the activity, which contains the various components and all the design elements that you can use to build the UI of your Android application.
It takes care of placing the layout file in the activity and also inflating the components present in the corresponding XML file. By doing this, it makes sure that all the components are place properly and are visible in the UI.
Therefore, whenever the user wants to create a new screen in their android application, all they need to do is select a proper layout file and set it using the setContentView() method. This helps to quickly create a look and feel of the application and make the UI much more intuitive and organized.
Why do we need to call setContentView () in onCreate () of activity class?
The setContentView() method is an essential part of the Android activity lifecycle and must be used in the onCreate() method of activity class. It defines the activity layout that will be used for the current activity and without it the activity layout will be empty.
The setContentView() method inflates the layout resource file and the View objects stored in the layout can then be accessed using findViewById(). It is also important to note that the setContentView() method should only be called once per activity and not multiple times in the same onCreate() method.
What is the difference between onCreate () and onStart ()?
The onCreate() method is called once, when the activity is created for the first time, and it is used for initializing the activity. It is a lifecycle method and is called after onStart() when the activity is created.
The onStart() method is called when the activity is becoming visible to the user. It is a lifecycle method and is called before onCreate() when the activity is visible or the app comes to foreground.
Generally, the onStart() method is used to begin the process of updating the user interface with values from the application, such as retrieving data from a database or setting up a broadcast receiver.
The onCreate() method is used to initialize the activity and set up any other necessary elements such as the user interface, settings, and state. It is also used to create and execute any background tasks that the activity requires.
In summary, the onCreate() method is called once, when the activity is created for the first time, and onStart() is called when the activity is becoming visible to the user.
How do you pass data to intents?
Intents are responsible for allowing activities to pass data to one another, and they do this by taking any data that has been passed along with the intent and making it available to the receiving activity via a Bundle object.
Intents themselves are essentially just messages that are passed between activities which can contain various types of data such as primitives, arrays, bundles, and Parcelables. To pass data to an Intent, you need to create a Bundle object and add the data that you want to pass in with a specific key, then set the bundle as part of the intent by calling intent.
putExtras(bundle). The receiving activity can then retrieve the bundle with intent. getExtras(). Once the bundle is retrieved it can be used to access the data associated with the key.
How many callback methods are in Android?
There are a variety of different callback methods used in Android, with the exact number depending on which versions and components of Android you are using. Generally speaking, there are roughly 10-15 callback methods used in the Android core, including methods such as onRestoreInstanceState(), onCreate(), onConfigurationChanged(), and onFinish().
In addition, developers can create their own callback methods for specific uses. For example, if you have a custom class to handle logins, you may create a callback to handle success and failure cases for the login.
Similarly, you may create OnClickListener objects to be called in response to user touches on screen elements.
Finally, there are system-level callbacks that can be used to create activities, broadcast intents, and more. For example, onReceive() is a callback associated with broadcast receivers that is used to process and act upon data sent through intents.
In summary, the exact number of callbacks used in Android can vary depending on the versions of Android and specific components being used. However, a typical Android system using the latest version of the Android core will utilize somewhere between 10-15 standard callback methods, plus whatever custom and system-level methods a particular developer chooses to use.