The document introduces Kotlin programming concepts like conditionals, null safety, nullable types, and object-oriented programming principles including encapsulation, abstraction, inheritance, polymorphism, and relationships between classes. It provides examples of syntax for if/else statements, declaring nullable types, and using the safe call and Elvis operators.

3. Welcome to
Day 2

6. Similar logic like other programming languages.
SYNTAX for basic if/else condition:

14. You learned how to use if/else and when as statements.
You can also use conditionals as expressions to return
different values for each branch of condition.

15. You learned how to use if/else and when as statements.
You can also use conditionals as expressions to return
different values for each branch of condition.

16. Kotlin null safety is a procedure to eliminate the risk of null reference from the code. Kotlin
compiler throws Null Pointer Exception immediately if it is found any null argument is passed
without executing any other statements.
In Java this would be the equivalent of a Null Pointer Exception, or an NPE for short.

17. Q01

18. Nullable types (can hold null) and
non-nullable types(can’t hold null)
Declare Nullable type:
Q01

19. Q01
Nullable types (can hold null) and
non-nullable types(can’t hold null)
Declare Nullable type:

20. Q01
Nullable types (can hold null) and
non-nullable types(can’t hold null)
Declare Nullable type:

21. Q02

23. The code fails at compile time because the direct reference to the length property for the favoriteActor
variable isn't allowed because there's a possibility that the variable is null.
This causes a critical issue - known as null reference - attempt to access a member of a variable that is null.
This might cause the app to crash. This type of crash is known as runtime error.
Due to the null safety nature of Kotlin, such runtime errors are prevented because the Kotlin compiler
forces a null check for nullable types. Null check refers to a process of checking whether a variable could be
null before it's accessed and treated as a non-nullable type. If you wish to use a nullable value as its non-
nullable type, you need to perform a null check explicitly.

24. The safe-call operator allows safer access to nullable variables because the Kotlin compiler stops any
attempt of member access to null references and returns null for the member accessed

25. The safe-call operator allows safer access to nullable variables because the Kotlin compiler stops any
attempt of member access to null references and returns null for the member accessed

26. It means that you assert that the value of the variable isn't null, regardless of whether it is or isn't.

27. It means that you assert that the value of the variable isn't null, regardless of whether it is or isn't.
You get Null Pointer Exception

28. Understanding the test:

29. If the variable isn't null, the expression before the ?: Elvis operator executes. If the variable is null, the
expression after the ?:
How can we express the previous problem using Elvis operator ?

30. If the variable isn't null, the expression before the ?: Elvis operator executes. If the variable is null, the
expression after the ?:
How can we express the previous problem using Elvis operator ?

31. OOPS in
Kotlin

32. OOPS in Kotlin
OOPs is generally the abbreviation of the name Object Oriented Programming. In simple language
suppose we want to build a car then first we have to make a design called CLASS and the real car
called OBJECT.
CLASS

33. OOPS in Kotlin
OOPs is generally the abbreviation of the name Object Oriented Programming. In simple language
suppose we want to build a car then first we have to make a design called CLASS and the real car
called OBJECT.
CLASS OBJECT

34. OOPS in Kotlin

35. OOPS in Kotlin
Encapsulation
Wraps the related properties and methods that perform action on
those properties in a class.

36. OOPS in Kotlin
Abstraction
The idea is to hide the internal implementation logic as much as
possible.

37. OOPS in Kotlin
Inheritance
Enables you to build a class upon the characteristics and behavior
of other classes by establishing a parent-child relationship.

38. OOPS in Kotlin
Polymorphism
Ability to use different objects in a single, common way.

39. OOPS in Kotlin
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40. OOPS in Kotlin

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44. Q03
OOPS in Kotlin

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51. v
OOPS in Kotlin

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56. OOPS in Kotlin
IS-A Relationship
HAS-A Relationship

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