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Android App Development Interview Questions
- What is an Activity in Android?
- An Activity is a single screen or user interface that a user can interact with. It represents a single screen with a user interface and typically takes up the full screen.
- What is a Fragment in Android?
- A Fragment is a part of an Activity, which contributes its own UI to that Activity. Fragments represent a reusable portion of a user interface in an Activity.
- What is the difference between Serializable and Parcelable in Android?
- Serializable is a standard Java interface for serializing objects, while Parcelable is an Android-specific interface for passing data between components.
- What is an Intent in Android?
- An Intent is a messaging object used to request an action from another app component, such as starting an Activity or Service.
- What is a Service in Android?
- A Service is a component that runs in the background to perform long-running operations without a user interface.
- What is a Content Provider in Android?
- A Content Provider is a component that manages access to a shared set of data, such as a SQLite database or a file.
- What is an Adapter in Android?
- An Adapter is a bridge between a UI component and a data source that provides data to the UI component.
- What is a Layout in Android?
- A Layout is a container that holds UI elements and arranges them on the screen.
- What is an XML file in Android?
- An XML file is a markup language used to define UI elements and other resources in Android.
- What is the AndroidManifest.xml file in Android?
- The AndroidManifest.xml file is a file that describes essential information about the app to the Android operating system, such as the app's name, permissions, and components.
- What is the difference between match_parent and wrap_content in Android?
- match_parent tells the view to match the parent view's size, while wrap_content tells the view to wrap itself around its contents.
- What is the difference between onCreate() and onStart() in Android?
- onCreate() is called when an Activity is created for the first time, while onStart() is called when an Activity is brought to the foreground.
- What is the difference between a Dialog and an AlertDialog in Android?
- A Dialog is a general term for a window that pops up and requires user interaction. An AlertDialog is a specific type of Dialog that presents the user with a set of options.
- What is the difference between a Handler and a Thread in Android?
- A Handler is an object that can post messages to a thread's message queue, while a Thread is an object that runs in the background.
- What is the difference between a ViewGroup and a View in Android?
- A ViewGroup is a container that holds other Views or ViewGroups, while a View is a UI element that a user can interact with.
- What is the difference between a BroadcastReceiver and a Service in Android?
- A BroadcastReceiver is a component that responds to system-wide broadcast announcements, while a Service is a component that runs in the background to perform long-running operations.
- What is the difference between an AsyncTask and a Thread in Android?
- An AsyncTask is a simple way to run code in the background without blocking the UI thread, while a Thread is a more low-level construct that requires more manual handling of thread synchronization.
- What is the difference between a Toast and a Snackbar in Android?
- A Toast is a small popup message that appears at the bottom of the screen and disappears after a short time, while a Snackbar is a longer message that appears at the bottom of the screen and can be dismissed
- What is the use of an AsyncTask in Android?
- AsyncTask is used to perform operations asynchronously on a background thread without blocking the main UI thread.
- What is the role of the onCreate() method in an Activity?
- The onCreate() method is called when an Activity is created for the first time, and it is used to initialize the Activity's state, UI, and other components.
- What is a Service in Android, and how is it different from an Activity?
- A Service is a component that runs in the background to perform long-running operations, while an Activity is a component that represents a single screen with a user interface.
- What is the difference between an implicit and explicit Intent in Android?
- An explicit Intent specifies the target component explicitly by its class name, while an implicit Intent does not specify the target component and relies on the system to find the appropriate component to handle the Intent.
- What is a BroadcastReceiver in Android, and how is it used?
- A BroadcastReceiver is a component that responds to system-wide broadcast announcements, such as changes in the network status, incoming SMS messages, etc.
- What is a ContentProvider in Android, and how is it used?
- A ContentProvider is a component that manages access to a shared set of data, such as a SQLite database, and provides a standardized interface to other components in the system.
- What is the difference between a Fragment and an Activity in Android?
- A Fragment is a part of an Activity, which contributes its own UI to that Activity, while an Activity is a single screen with a user interface.
- What is a Loader in Android, and how is it used?
- A Loader is a component that loads data asynchronously and delivers it to an Activity or Fragment when it is ready.
- What is a PendingIntent in Android, and how is it used?
- A PendingIntent is a token that represents a deferred Intent, allowing an application to perform an operation at a later time without requiring a user's interaction.
- What is the difference between a TextView and an EditText in Android?
- A TextView is a UI element that displays text, while an EditText is a UI element that allows the user to input text.
- What is the role of the AndroidManifest.xml file in Android?
- The AndroidManifest.xml file is used to describe the essential information about an app to the Android operating system, such as the app's name, permissions, and components.
- What is the difference between the OnCreate() and OnStart() methods in an Activity in Android?
- OnCreate() is called when an Activity is first created, while OnStart() is called when an Activity becomes visible to the user.
- What is the difference between a Service and an IntentService in Android?
- A Service is a component that runs in the background to perform long-running operations, while an IntentService is a subclass of Service that processes Intents one at a time, on a separate worker thread.
- What is a FragmentTransaction in Android, and how is it used?
- A FragmentTransaction is an API used to perform a set of Fragment operations, such as adding, removing, or replacing a Fragment, in a transactional manner.
- What is the difference between the OnResume() and OnRestart() methods in an Activity in Android?
- OnResume() is called when an Activity becomes visible to the user, while OnRestart() is called when an Activity is being restarted after being stopped.
- What is the difference between Serializable and Parcelable in Android?
- Serializable is a standard Java interface used to serialize an object to a byte stream, while Parcelable is an Android-specific interface that is optimized for serialization and deserialization of objects between components in the system.
- What is the difference between a Thread and a Handler in Android?
- A Thread is a component that executes code in a separate thread, while a Handler is a component that allows communication between threads, such as sending messages or posting Runnable objects.
- What is a RecyclerView in Android, and how is it used?
- A RecyclerView is a UI element used to display large sets of data in a scrollable list or grid, and it provides a flexible and efficient way to recycle views that are no longer visible.
- What is the role of the onSaveInstanceState() method in an Activity in Android?
- The onSaveInstanceState() method is called before an Activity is destroyed, and it is used to save the state of the Activity's UI and other components, which can be restored later when the Activity is recreated.
- What is the difference between a ConstraintLayout and a RelativeLayout in Android?
- A RelativeLayout is a layout that positions its child views relative to each other or the parent view, while a ConstraintLayout is a layout that allows you to create complex layouts by defining constraints between views.
- What is the role of the LayoutInflater in Android, and how is it used?
- The LayoutInflater is a component that is used to inflate XML layout files into their corresponding View objects, which can then be added to an Activity or Fragment.
- What is a ThreadPoolExecutor in Android, and how is it used?
- A ThreadPoolExecutor is a component that manages a pool of threads for executing tasks in parallel, and it provides a way to control the maximum number of threads, the queue size, and other parameters.
- What is a Toast in Android, and how is it used?
- A Toast is a UI element used to display a short message to the user, typically at the bottom of the screen, and it disappears automatically after a short time.
- What is the role of the onCreateOptionsMenu() method in an Activity in Android?
- The onCreateOptionsMenu() method is called when an Activity's options menu is first created, and it is used to inflate the menu layout and add menu items to it.
- What is the role of the onResume() method in an Activity in Android?
- The onResume() method is called when an Activity becomes visible to the user, and it is used to resume any ongoing operations or update the UI.
- What is the difference between a ListView and a GridView in Android?
- A ListView is a UI element used to display a scrollable list of items in a vertical or horizontal layout, while a GridView is a UI element used to display items in a grid pattern.
- What is the difference between a Sticky Intent and a Normal Intent in Android?
- A Sticky Intent is an Intent that stays in the system even after it has been broadcasted, while a Normal Intent is an Intent that is delivered to its target component and then discarded.
- What is a CursorLoader in Android, and how is it used?
- A CursorLoader is a component used to load data from a ContentProvider asynchronously and deliver it to an Activity or Fragment, and it provides automatic management of the Cursor's lifecycle.
- What is a Service in Android, and how is it used?
- A Service is a component that runs in the background to perform long-running tasks or handle incoming requests, and it can be started, stopped, or bound to by other components in the system.
- What is the difference between an AsyncTask and a Thread in Android?
- An AsyncTask is a convenient way to perform short-lived background tasks and update the UI, while a Thread is a more general-purpose mechanism for executing code in a separate thread.
- What is the role of the onConfigurationChanged() method in an Activity in Android?
- The onConfigurationChanged() method is called when a configuration change occurs, such as a change in screen orientation or language, and it allows the Activity to handle the change without being destroyed and recreated.
- What is the role of the onCreate() method in an Activity in Android?
- The onCreate() method is called when an Activity is first created, and it is used to initialize the Activity's UI and other components.
- What is the difference between a Broadcast Receiver and an Intent Service in Android?
- A Broadcast Receiver is a component that listens for system-wide events and responds to them, while an Intent Service is a component that performs a background task and then stops itself when it is finished.
- What is a ContentProvider in Android, and how is it used?
- A ContentProvider is a component that manages access to a shared data repository, such as a database or file system, and it provides a standard interface for other components to query, insert, update, or delete data.
- What is the difference between a Fragment and an Activity in Android?
- An Activity is a component that represents a single screen in an app, while a Fragment is a reusable UI component that can be added or removed from an Activity dynamically.
- What is a Loader in Android, and how is it used?
- A Loader is a component used to load data from a ContentProvider asynchronously and deliver it to an Activity or Fragment, and it provides automatic management of the Loader's lifecycle.
- What is the role of the onActivityResult() method in an Activity in Android?
- The onActivityResult() method is called when an Activity that started another Activity receives a result, such as a user selection or input, and it is used to process the result and update the UI.
- What is the role of the onDestroy() method in an Activity in Android?
- The onDestroy() method is called when an Activity is about to be destroyed, and it is used to release any resources or clean up any ongoing operations.
- What is the difference between a Service and a BroadcastReceiver in Android?
- A Service is a component that runs in the background to perform long-running tasks or handle incoming requests, while a BroadcastReceiver is a component that listens for system-wide events and responds to them.
- What is the role of the onNewIntent() method in an Activity in Android?
- The onNewIntent() method is called when a new Intent is received for an Activity that is already running, and it allows the Activity to handle the new Intent without being destroyed and recreated.
- What is the difference between a Bound Service and a Started Service in Android?
- A Bound Service is a service that allows other components to bind to it and interact with it, while a Started Service is a service that is started and stopped explicitly by other components.
- What is the role of the onCreate() method in a Service in Android?
- The onCreate() method is called when a Service is first created, and it is used to initialize the Service's resources and other components.
- What is the difference between Serializable and Parcelable in Android?
- Serializable is a Java interface that allows an object to be converted into a stream of bytes for storage or transmission, while Parcelable is an Android-specific interface that provides a more efficient mechanism for transferring data between components.
- What is a View in Android, and how is it used?
- A View is a basic UI component in Android that represents a rectangular area on the screen and can be used to display text, images, buttons, and other UI elements.
- What is the difference between match_parent and wrap_content in Android?
- match_parent is a layout parameter that tells a View to match its parent's size, while wrap_content tells a View to size itself to fit its content.
- What is the role of the onCreateOptionsMenu() method in an Activity in Android?
- The onCreateOptionsMenu() method is called when an Activity needs to create its menu options, and it is used to inflate the menu layout and add items to the menu.
- What is the role of the onOptionsItemSelected() method in an Activity in Android?
- The onOptionsItemSelected() method is called when a menu item in an Activity's options menu is selected, and it is used to handle the selection and perform the appropriate action.
- What is the difference between a GridLayout and a TableLayout in Android?
- GridLayout is a layout manager that arranges its child views in a grid-like pattern, while TableLayout is a layout manager that arranges its child views in a table-like pattern.
- What is a FragmentManager in Android, and how is it used?
- A FragmentManager is a component that manages Fragments within an Activity, and it provides methods for adding, removing, and replacing Fragments dynamically.
- What is the role of the onResume() method in an Activity in Android?
- The onResume() method is called when an Activity becomes visible and interactive again, and it is used to resume any ongoing operations or refresh the UI.
- What is the role of the onRestoreInstanceState() method in an Activity in Android?
- The onRestoreInstanceState() method is called when an Activity is being restored from a previously saved state, and it is used to restore any previously saved data or UI state.
- What is the difference between a View and a ViewGroup in Android?
- A View is a basic UI component that can be added to a ViewGroup to create a more complex UI layout.
- What is a RecyclerView in Android, and how is it used?
- A RecyclerView is a more advanced version of the ListView that can handle larger data sets and provide better performance by recycling Views.
- What is the difference between the res and assets directories in an Android project?
- The res directory contains resources, such as layout files, images, and strings, that are compiled into the app, while the assets directory contains raw data files that are included in the app as-is.
- What is a PendingIntent in Android, and how is it used?
- A PendingIntent is an object that allows a component, such as a Service or BroadcastReceiver, to perform an action on behalf of another component, such as launching an Activity or sending a notification.
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