Android Interview Questions and Answers
Question - 91 : - What is DialogFragment?
Answer - 91 : -
A DialogFragment is a fragment that floats on top of the current activity window and displays a modal window. An instance of DialogFragment can be used to display an existing Dialog implementation dialog or a custom view hierarchy by using the Dialog class that is the base class for implementing a dialog.
Question - 92 : - What is presenter?
Answer - 92 : -
The Presenter acts as a mediator between model and view. All your presentation logic belongs to the presenter which is responsible for querying the model and updating the view, reacting to user interactions, and updating the model.
Question - 93 : - What is Bitmap pooling in android?
Answer - 93 : -
You can avoid continuous allocation and deallocation of memory in your application by using the Bitmap pool, you can reduce GC overhead, which results in a smooth-running application.
Question - 94 : - What is the use of Android manifest.xml?
Answer - 94 : -
Every application should have an Androidmanifest.xml file at the root of the project source set. This file describes the essential information required by the user for the app to the Android build tools. Apart from this, it is required for the following reasons:
- To give permission that the application requires to ensure the access is protected.
- To provide with the hardware and software features, which the app requires when installing from Google play etc.
Question - 95 : - What are services in Android and what is its type?
Answer - 95 : -
Services here is an application component that can perform long-duration operations in the background. It doesn’t provide a user interface. Other application components can start a service and can continue to perform/ run in the background when the users switch to some other application. There are three different types of services:
- Foreground: The activity of performing the operation in foreground service is noticeable to the users. A notification is displayed for the same.
- Background: Generally, a background service performs its operations, which is directed not noticed by the users on their screen. Example if an app uses service to compact its storage this will be considered as background service.
- Bound: A service is bound when an application component binds to it by calling it as bind service. A bound service runs only as long as another application component is bound to it.
Question - 96 : - What options do the users get to save data in Android?
Answer - 96 : -
Android provides some options to save or store the app data. Here the choice depends on the specific needs and requirement of space by the users.
Few of the data storage options available on Android are as follows:
- Internal file storage: stores the private file on the device file system.
- External file storage: stores the file on the shared external file system.
- Shared preferences: stores the private primitive data in key-value pairs.
- Databases: stores the structured data in a private database.
To expose one app’s data to other apps, the content provider can be used.
Question - 97 : - What does Fragment mean?
Answer - 97 : -
A fragment means behavior or the portion of user interface in a Fragment Activity. One can combine multiple fragments in a single activity to build a UI and can reuse the fragment in multiple activities. The fragment can be considered as a modular section of an activity. This has its life cycle, gets its input events, which can be added or removed accordingly. It is must host a fragment in an activity and fragments lifecycle is directly related by the host activity’s lifecycle.
Question - 98 : - What are the Android application components?
Answer - 98 : -
Android application components are the building block essentially used in the Android application. The application manifest file named Android manifest.xml couples the components. This describes each component of the application and describes how they interact, and then the processing activity takes place.
There are four main components, which are:
- Activities: They show the UI and handle the interaction of the users in smartphone screen.
- Services: They take care of the processing associated with the application.
- Broadcast Receivers: They handle the communication process between Android OS and application.
- Content Providers: They handle issues with data and database management.
Question - 99 : - What is Android?
Answer - 99 : -
Android is an open-sourced operating system by Linux that is primarily used in mobile devices like cell phones and tablets. This Linux kernel based system is equipped with high and advanced components that allow developers to create and run apps. Therefore performs the basic as well as the advanced functions.
Question - 100 : - What is Espresso?
Answer - 100 : -
The Espresso is a testing framework for Android. It is an easier way to write reliable user interface tests. It automatically synchronizes your test actions with the UI of your application. It also ensures that your activity is started before the tests run.