These are the Common interview Questions that an android developer can expect while appearing for an Android Developing
What is Android?
Android is an open-source, Linux-based operating system that is used in mobiles and tablets, etc… It is a Linux kernel-based system that’s been equipped with rich components that allows developers to create and run apps that can perform both basic and advanced functions
Who is the founder of Android?
What Is the Google Android SDK?
The Google Android SDK is a tool set that developers need in order to write apps on Android enabled devices. It contains a graphical interface that emulates an Android driven handheld environment, allowing them to test and debug their codes.
What is the Android Architecture?
Android Architecture is made up of 4 key components:
a. Linux Kernel
c. Android Framework
d. Android Applications
What is Android Framework?
The Android Framework is an important aspect of the Android Architecture. Here you can find all the classes and methods that developers would need in order to write applications on the Android environment.
What is activity?
Activity is like a frame or window in java that represents GUI. It represents one screen of android.
What is the use of an activity Creator?
An activity Creator is the first step towards the creation of a new Android project. It is made up of a shell script that will be used to create new file system structure necessary for writing codes within the Android IDE.
What is AAPT?
AAPT is short for Android Asset Packaging Tool. This tool provides developers with the ability to deal with zip-compatible archives, which includes creating, extracting as well as viewing its contents.
Which items are important in every Android project?
These are the essential items that are present each time an Android project is created:
What is the importance of XML-based layouts?
The use of XML-based layouts provides a consistent and somewhat standard means of setting GUI definition format. In common practice, layout details are placed in XML files while other items are placed in source files.
What are containers?
Containers, as the name itself implies, holds objects and widgets together, depending on which specific items are needed and in what particular arrangement that is wanted. Containers may hold labels, fields, buttons, or even child containers, as examples.
What is Orientation?
Orientation, which can be set using setOrientation(), dictates if the Linear Layout is represented as a row or as a column. Values are set as either HORIZONTAL or VERTICAL.
What is adb?
Adb is short for Android Debug Bridge. It allows developers the power to execute remote shell commands. Its basic function is to allow and control communication towards and from the emulator port.
What are the four essential states of an activity?
Active – if the activity is at the foreground
Paused – if the activity is at the background and still visible
Stopped – if the activity is not visible and therefore is hidden or obscured by another activity
Destroyed – when the activity process is killed or completed terminated
What is ANR?
ANR is short for Application Not Responding. This is actually a dialog that appears to the user whenever an application have been unresponsive for a long period of time.
When does ANR occur?
The ANR dialog is displayed to the user based on two possible conditions. One is when there is no response to an input event within 5 seconds, and the other is when a broadcast receiver is not done executing within 10 seconds.
What is intent?
It is a kind of message or information that is passed to the components. It is used to launch an activity, display a web page, send sms, send email etc. There are two types of intents in android:
i. Implicit Intent
ii. Explicit Intent
What is Implicit Intent?
Implicit intent is used to invoke the system components.
What is Explicit Intent?
Explicit intent is used to invoke the activity class.
What is the function of an intent filter?
Because every component needs to indicate which intents they can respond to, intent filters are used to filter out intents that these components are willing to receive. One or more intent filters are possible, depending on the services and activities that is going to make use of it.
What are the different states wherein a process is based?
There are 4 possible states:
i. foreground activity
ii. visible activity
iii. background activity
iv. empty process
What is the AndroidManifest.xml?
This file is essential in every application. It is declared in the root directory and contains information about the application that the Android system must know before the codes can be executed.
What is the importance of Default Resources?
When default resources, which contain default strings and files, are not present, an error will occur and the app will not run. Resources are placed in specially named subdirectories under the project res/ directory.
What is AIDL?
Android Interface Definition Language, handles the interface requirements between a client and a service so both can communicate at the same level through inter process communication or IPC. This process involves breaking down objects into primitives that Android can understand. This part is required simply because a process cannot access the memory of the other process.
What data types are supported by AIDL?
AIDL has support for the following data types:
· Char Sequence
· all native Java data types like int, long, char and Boolean
What is a Fragment?
A fragment is a part or portion of an activity. It is modular in a sense that you can move around or combine with other fragments in a single activity. Fragments are also reusable.
What is a resource?
A user defined JSON, XML, bitmap, or other file, injected into the application build process, which can later be loaded from code.
What is a visible activity?
A visible activity is one that sits behind a foreground dialog. It is actually visible to the user, but not necessarily being in the foreground itself.
What is the APK format?
The APK file is compressed AndroidManifest.xml file with extension .apk. It also includes the application code (.dex files), resource files, and other files which are compressed into a single .apk file.
What are the core components under the Android application architecture?
There are 5 key components under the Android application architecture:
i. Services like Network Operation
ii. Intent – To perform inter-communication between activities or services
iii. Resource Externalization – such as strings and graphics
iv. Notification signaling users – light, sound, icon, notification, dialog etc…
v. Content Providers – They share data between applications
What is a Sticky Intent?
A Sticky Intent is a broadcast from send StickyBroadcast() method such that the intent floats around even after the broadcast, allowing others to collect data from it.
What is portable wi-fi hotspot?
Portable Wi-Fi Hotspot allows you to share your mobile internet connection to other wireless device. For example, using your Android-powered phone as a Wi-Fi Hotspot, you can use your laptop to connect to the Internet using that access point.
What is an action?
In Android development, an action is what the intent sender wants to do or expected to get as a response. Most application functionality is based on the intended action.
What is the use of WebView in android?
A WebView is an android UI component that displays webpages. It can either display a remote webpage or can also load static HTML data. This encompasses the functionality of a browser that can be integrated to application. WebView uses the WebKit rendering engine to display web pages and includes methods to navigate forward and backward through a history, zoom in and out, etc…
Does android support other language than java?
Yes, android app can be developed in C/C++ also using android NDK (Native Development Kit). It makes the performance faster. It should be used with android SDK.