amitshekhariitbhu / android-interview-questions Goto Github PK

Hey guys, this README is filled with plenty of wonderful Questions and I think that addition of What is AppCompatActivity ? under Core Android might be helpful 🎉

What is the right answer for design questions?
Design WhatsApp

The best and average time for quicksort is O(n log(n)), not O(n^2).

What is Espresso? Link is Broken.
Working link https://developer.android.com/training/testing/espresso

The github link provided with the question "Differences between abstract classes and interfaces?" is not available anymore. Please remove/update it.

In your blog post about Retrofit with Kotlin Flow, you used an API helper class instead of a repository. Was this approach only for the tutorial, or can we also follow it in an actual project? Thank you for your help." @amitshekhariitbhu

To my knowledge answer to this question: "What are the access modifiers you know? What does each one do?" is wrong.

default is more restrictive than protected because default's scope is within the same class and package whereas the scope of protected is the same class, same package, and other packages as well through inheritance.

So the order of the access modifiers from the least restrictive to the most restrictive should be:
public > protected > default > private

The github link provided with the question "Explain unit test" is not available anymore. Please remove/update it.

There are few sections like Serialization, Parcelable and Strings duplicated. Can be removed and consolidated.

While reading I found that there was a question under OOPS section that

Can you list 8 primitive types in java?

Present ans:
byte
short
int
long
float
double
char
String
boolean

Expected ans:

byte
short
int
long
float
double
char
boolean

String is not a primitive data type of Java.

This point may mislead a beginner.

In the very top of the guide, you wrote "A Array" instead of the correct "An Array".

This is really awesome! It really helps to prepare for the Android developer interview. When will we have answers? Some questions are hard or too general to me, it's difficult to find the answer.

Thanks

Parcelable was created to be more efficient then Serializable.
"then" should change to "than".

test

For the question
Can you list 8 primitive types in java?
in Objects and Primitives section, String is listed as an extra Primitive data type.

According to the Java documentation (here),

The String class is not technically a primitive data type

Hi all,

I found that there is a better visualized article on activity launch modes with a more descriptive explanation.

https://inthecheesefactory.com/blog/understand-android-activity-launchmode/en

Is it possible to link to this article on the Activity -> What are "launch modes" ?

What is the NDK and why is it useful? - Learn from here and here and here

I would like to know how Android Applications are Pre-Installed in Android Devices. Can we make our application as Pre-installed app like Disabling "Unintall" Button at Application Information Page and show "Disable" Button.

LinkedList has O(1) complexity only on insertions to a head of the list. Insertions to middle causes traversal that takes O(n)

Not updated questions "How does the Hilt work? "

What is serialization? How do you implement it?

Serialization is the process of converting an object into a stream of bytes in order to store an object into memory so that it can be recreated at a later time while still keeping the objects original state and data. In Java there are two methods of doing this, one is by implementing Serializable or Parcelable.

Parcelable is Android exclusive. Java has Externalizable.

In Android, however, Serializable should never be used in Android.

That's like saying you should never use enums on Android. (You shouldn't use enums to represent an integer or string constant.)

Parcelable was created to be more efficient then Serializable, and performs about 10x faster then Serializable because Serializable uses reflection which is a slow process and tends to create a lot of temporary objects which may cause garbage collection to occur more often.

That's the default if you just stamp Serializable interface onto a class and don't override writeObject or don't implement Externalizable. There's no mention that Parcelable is not as automatic as Serializable.

@amitshekhariitbhu Can we populate the conepts/topics in the repo with links/references of external sources other than Mindorks . 😟

The descriptions are inverted.

Instantiation is when you allocate memory in the heap (for objects)
Initialization is when you assign a value to the object's fields.

https://docs.oracle.com/javase/tutorial/java/javaOO/objectcreation.html

@amitshekhariitbhu, I love your work here, and I understand that to maintain the integrity of this project, you probably don't want too many chefs in the kitchen.

This project has helped thousands of people across the world, and I'm sure there are many developers that would love to give back and contribute after having benefited HEAVILY from them (myself included).

Any suggestions on how we can accomplish this moving forward?

A few things I have in mind:

• I understand that the answers provided by anyone can possibly contain errors, so before submitting, pull requests must be approved by at least 3 developers who are not the owner in order to be merged.
• Upon reviewing, sources must be included either in the pull request, or by reviewers upon approving, to make sure that the PR is free from error; basically fact-check the PR.
• Moving forward, if there are trusted devs who have heavily contributed to this project, besides @amitshekhariitbhu, maybe they can also be added as maintainers?
• Once we have more than one maintainer, a PR can be merged as long as it has met the above requirements OR has been approved by at least one maintainer.

It should be onSaveInstanceState() not onSavedInstanceState()

What are "launch modes"? Mindorks
"Mindorks" link is not Live anymore, it showing this error "Cannot GET /android-%60Activity%60-launchmode-explained-cbc6cf996802"

This is a very useful repository with lots of views on daily basis.

Hence I would suggest increasing readability, it would be great if change questions to bold and keep answers in the normal fonts.

This way it would be easy to distinguish between the two especially with the increase in text size, it will make it much easier for users to read.

Enumeration don't have remove() method

Iterator have hasNext(), next(), remove() method.
Enumeration have hasMoreElement(), nextElement() method only

I think it would be great to separate the questions between junior, middle and senior