Top Java Android Interview Questions - NullClass

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Top Java Android Interview Questions

Hello there, if you’re looking for some Android interview questions to help you prepare for an Android app developer interview, you’ve come to the perfect spot. We’ll look at some of the most common Android interview questions in this article.

Android is one of the most popular mobile and smartphone operating systems today, and it is a strong competitor to Apple’s iOS. A career as an Android application developer is also in high demand. In an Android interview, I’ve also encountered a few of Java queries. It’s thus a good idea to prepare some Java questions as well.

These Android Interview Questions are quite simple in nature, however they come regularly in numerous Android interviews for beginners and intermediate programmers. I had not previously supplied responses to this question, but I have now updated the majority of them.

These questions are useful for rehearsing and practising for the Android interview. If you like, you may also contribute Android interview questions that have been posed to you, even if you don’t know the answers.

Here are a few Android interview questions culled from several telephonic and face-to-face interviews. It may be used by any Java programmer to prepare for the Android interview.

So let’s get started :

Question 1: What is the difference between a regular .png and a nine-patch image?


This is one of the most common Android interview questions, which has been asked in a variety of interviews, ranging from 1 to 2 years of experience to 5 years of experience. It is a resizeable bitmap resource that may be used for backdrops or other graphics on the device, according to the response.

The NinePatch class allows you to design a bitmap in nine different portions. The extension of the nine patch pictures is.9.png. It provides for 9 different extensions, including 4 unscaled corners, 4 scaled edges in one dimension, and a centre one that may be scaled in both directions.


Question 2: What is an ANR notification in Android?


The abbreviation ANR stands for “Application Not Responding.” This pop up appears on Android systems when an application is doing too much work on the main thread and has been unresponsive for a long time.


Question 3: When does the onResume() method call?


Another question about androids that is regularly asked in interviews. The onResume() function is part of the activity lifecycle. When the action is brought to the foreground, this is referred to as. When the activity is launched, restarted, or comes to the foreground, you can override this method in your activity to run code.

Question 4: What is the APK format?


The APK file is a compressed AndroidManifest.XML file with the extension.apk that contains application code (.dex files), resource files, and other files in a single.apk file.


Question 5: What is the difference between implicit intent and explicit intent?


Let’s look at the differences between the two sorts of purpose: implicit and explicit intent.

1) Implicit intent occurs when you use the system’s default intent, such as sending an email, sending an SMS, dialling a phone number, and so on.


Intent sendIntent = new Intent();
sendIntent.putExtra(Intent.EXTRA_TEXT, textMessage);

2) Explicit: When you call you’re on application activity from one activity to another, you’re expressing your explicit goal.
For example, from the first to the second activity.

Intent intent = new Intent(first.this, second.class);

Question 6: What is the Dalvik Virtual Machine?


Android applications operate on the Dalvik Virtual Machine, the same way Java applications run on Oracle HotSpot JVM or Azul JVM.


Question 7: How do Android app run on Android mobile?


Because Android code is written in Java, it is compiled first and then run, but the JVM used to produce the bytecodes is not the same as the normal JVM. The Android app is operated on the Dalvik JVM.


Question 8: Pointers are used in C/ C++. Why does Java not make use of pointers?


Beginner programmers should avoid using pointers since they are fairly difficult. The use of pointers might make Java difficult, since it focuses on code simplicity. The usage of a pointer might also lead to mistakes. Furthermore, when pointers are utilized, security is undermined since pointers allow people to directly access memory.

By not including pointers in Java, a certain amount of abstraction is provided. Furthermore, the use of pointers might make trash collection time-consuming and inaccurate. References are used in Java because, unlike pointers, they cannot be changed.


Question 9: What is the difference between JDK, JRE, and JVM?


JVM stands for Java Virtual Machine, and it is an abstract machine that offers a runtime environment for Java bytecode execution. It is a standard that describes how the Java Virtual Machine works. Oracle and other firms have helped with its adoption. JRE is the name of the programme that implements it.

There are JVMs for a variety of hardware and software systems (so JVM is platform dependent). It is a runtime instance that is produced when the Java class is executed. The JVM is divided into three parts: specification, implementation, and instance.


JRE (Java Runtime Environment) is an acronym for Java Runtime Environment. It is the JVM implementation. The Java Runtime Environment (JRE) is a collection of software tools for creating Java applications. It’s responsible for creating the runtime environment. It is the JVM implementation. Furthermore, it is a real thing. It comprises a collection of libraries as well as other files that JVM utilizes during execution.

The term JDK stands for Java Development Kit. It’s a software development environment for creating Java applets and apps. It is a real thing. Likewise, it includes JRE as well as developer tools. JDK is an implementation of Oracle Corporation’s Java Platforms, as listed below:

  • Standard Edition Java Platform
  • Enterprise Edition Java Platform
  • Micro Edition Java Platform

Question 10: What are the advantages of Packages in Java?


The benefits of defining packages in Java are numerous.

1. Name collisions are avoided by using packages.
2. The package makes it easy to manage access.
3. We may also have hidden classes that are not accessible outside the package but are utilized by it.
4. It’s a lot easier to find the classes that are linked.

I hope you get an idea about the type of questions asked in Java android interviews.

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With that we end this blog . Have a nice day

October 30, 2021

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