Top kotlin interview questions and answers for experienced

 Top kotlin interview questions and answers for experienced

1.      What are the various data types available in Kotlin? Explain them.

Primitive data types are the most basic data types in Kotlin, and all others are reference types like array and string. Kotlin contains all data types as objects. Following are the different data types available in Kotlin:-

 

2. How are variables declared in Kotlin? What are the different types of variables in Kotlin? Explain with examples.

Every variable in Kotlin must be declared before it can be used. An attempt to use a variable without declaring it results in a syntax error. The type of data you are authorized to put in the memory address is determined by the variable type declaration. The type of variable can be determined from the initialized value in the case of local variables.

For example,

var site = "interviewbit"

 

3. What are data classes in Kotlin? Explain with a proper example.

The Data class is a simple class that holds data and provides typical functions. To declare a class as a data class, use the data keyword. 

·         equals() - The equals() function returns true if two objects have the identical contents. It operates similarly to "==," although for Float and Double values it works differently.

·         hashCode() - The hashCode() function returns the object's hashcode value.

·         copy() - The copy() function is used to duplicate an object, changing only a few of its characteristics while leaving the rest unaltered.

·         toString() - This function returns a string containing all of the data class's parameters.

To ensure consistency, data classes must meet the following requirements:

 

4. Explain the concept of null safety in Kotlin.

Kotlin's type system aims to eradicate null references from the code. If a program throws NullPointerExceptions at runtime it might result in application failure or system crashes. If the Kotlin compiler finds a null reference it throws a NullPointerException.

 

5. What is the difference between the variable declaration with var and Val?

If you want to declare some mutable(changeable) variable, then you can use var. For the immutable variable, use val i.e. val variables can't be changed once assigned.

6. How to ensure null safety in Kotlin?

One of the major advantages of using Kotlin is null safety. In Java, if you access some null variable then you will get a NullPointerException. So, the following code in Kotlin will produce a compile-time error:

7. What is Elvis's operator in Kotlin?

In Kotlin, you can assign null values to a variable by using the null safety property. To check if a value is having null value then you can use if-else or can use the Elvis operator i.e. ?: For example:

8. What is a data class in Kotlin?

Data classes are those classes that are made just to store some data. In Kotlin, it is marked as data. The following is an example of the same:

9. What is the difference between lateinit and lazy in Kotlin?

• lazy can only be used for val properties, whereas lateinit can only be applied to var because it can’t be compiled to a final field, thus no immutability can be guaranteed.
• If you want your property to be initialized from outside in a way probably unknown beforehand, use lateinit.

 

10. What is the difference between ArrayAdapter and BaseAdapter in Android?

Here is the difference: BaseAdapter is a very generic adapter that allows you to do pretty much whatever you want. However, you have to do a bit more coding yourself to get it working. ArrayAdapter is a more complete implementation that works well for data in arrays or ArrayList