Android interview questionsDownload Android interview questions PDF
Android interview questions
Permission allows certain restrictions to be imposed primarily to protect data and code. Without this, codes could be compromised, resulting in defects in the actual function.
AAPT is Android Asset packing tool. This provides developers with the ability to deal with zip-compatible archives, and it includes creating, extracting as well as viewing its content.
Few of the disadvantages of Android in the mobile market are as follows:
- Developers can write and register apps that will only run under the Android environment.
- With the growing popularity and demand for the Android mobile devices, developers can easily take advantage of this trend by uploading the app on the market for the distribution purpose, and people can download it.
The four initial stages of the activity are as followed:
- Active: If the activity is in the foreground that means it is running on the device.
- Paused: When the activity is at the background and is still visible on the screen.
- Stopped: when the activity is not visible and is actually hidden by another activity that is running on the device.
- Destroyed: when the activation process is killed or is terminated, it’s considered to be completely destroyed.
Activities are windows to an interface. Like a window is created with the aim to display the output and to know about input in the form of a dialogue box. In the same manner, activities play its role, may not always in the form of a user interface.
Intents help to display the notification message to the user from within the Android device. Users are made to response this alert.
The important items for Android projects are:
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.
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.
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.
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.
AIDL is Android Interface Definition Language. This IDL allows the user to define the programming interface; both the clients and service agree upon to communicate with each other using inter-process communication (IPC). On Android platform, it becomes difficult for one processor to access the memory of another process. They need to decompose their objects into primitive that the operating system can manage, and marshal the objects across. The code to perform that marshaling is tedious to write therefore Android handles this for the users with the help of AIDL
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.
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