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Questions and Answers
Android development has been Kotlin-first since Google I/O in 2019.
Android development has been Kotlin-first since Google I/O in 2019.
True (A)
What percentage of professional Android developers use Kotlin as their primary language?
What percentage of professional Android developers use Kotlin as their primary language?
50%
Kotlin is known for its complexity and difficult learning curve.
Kotlin is known for its complexity and difficult learning curve.
False (B)
Which of the following are benefits of using Kotlin for Android development? (Select all that apply)
Which of the following are benefits of using Kotlin for Android development? (Select all that apply)
The smallest Kotlin program is a ______ function.
The smallest Kotlin program is a ______ function.
Function names in Kotlin should follow the CamelCase convention.
Function names in Kotlin should follow the CamelCase convention.
What is the special word used to define a function in Kotlin?
What is the special word used to define a function in Kotlin?
What does the following line of code do? println("Hello, world!")
What does the following line of code do? println("Hello, world!")
In a function definition, what denotes the type of value the function returns?
In a function definition, what denotes the type of value the function returns?
What is the symbol used to represent a string in Kotlin?
What is the symbol used to represent a string in Kotlin?
Kotlin allows you to define a function that doesn't take any inputs.
Kotlin allows you to define a function that doesn't take any inputs.
If a variable is declared using the keyword val, can its value be changed later?
If a variable is declared using the keyword val, can its value be changed later?
What is the keyword used to declare variables that can be modified?
What is the keyword used to declare variables that can be modified?
What symbol is used to embed a variable's value into a string?
What symbol is used to embed a variable's value into a string?
Kotlin typically requires you to specify data types for variables, but it uses type inference to simplify the process in certain cases.
Kotlin typically requires you to specify data types for variables, but it uses type inference to simplify the process in certain cases.
In Kotlin, a function that returns a value is called a 'value function'.
In Kotlin, a function that returns a value is called a 'value function'.
Kotlin requires that a 'return' statement be included in every function that has a block body.
Kotlin requires that a 'return' statement be included in every function that has a block body.
How do you specify a 'nullable' type for a variable in Kotlin?
How do you specify a 'nullable' type for a variable in Kotlin?
The operator !! is used to ensure a variable has a value before accessing it.
The operator !! is used to ensure a variable has a value before accessing it.
What keyword is used to check if an expression is an instance of a specific type in Kotlin?
What keyword is used to check if an expression is an instance of a specific type in Kotlin?
When an immutable variable is checked for a specific type, Kotlin automatically casts it to that type without explicit casting.
When an immutable variable is checked for a specific type, Kotlin automatically casts it to that type without explicit casting.
What is the IDE used for developing Android applications?
What is the IDE used for developing Android applications?
Android Studio is only compatible with Kotlin and does not support Java development.
Android Studio is only compatible with Kotlin and does not support Java development.
Android Studio includes an emulator that allows you to test your Android app on various Android devices.
Android Studio includes an emulator that allows you to test your Android app on various Android devices.
What is the name of the programming language officially recommended for developing Android applications?
What is the name of the programming language officially recommended for developing Android applications?
Kotlin is a dynamically typed language.
Kotlin is a dynamically typed language.
In Kotlin, a variable can be declared without specifying its type, as long as it is assigned a value.
In Kotlin, a variable can be declared without specifying its type, as long as it is assigned a value.
Which of the following are valid keywords in Kotlin used for declaring variables? (Select all that apply)
Which of the following are valid keywords in Kotlin used for declaring variables? (Select all that apply)
What is the syntax for creating a range in Kotlin?
What is the syntax for creating a range in Kotlin?
What is Kotlin's keyword for creating a list that can be modified?
What is Kotlin's keyword for creating a list that can be modified?
The arrayOf function creates a mutable array in Kotlin.
The arrayOf function creates a mutable array in Kotlin.
How do you access a specific element in an array in Kotlin?
How do you access a specific element in an array in Kotlin?
What is the function used to create a blank array in Kotlin?
What is the function used to create a blank array in Kotlin?
The !! operator is used to check if a variable is null.
The !! operator is used to check if a variable is null.
Kotlin's is operator checks for a specific type without casting.
Kotlin's is operator checks for a specific type without casting.
What is the name of the function in Kotlin used to convert an array into a formatted string?
What is the name of the function in Kotlin used to convert an array into a formatted string?
Kotlin's println function is used for printing to the console.
Kotlin's println function is used for printing to the console.
If an expression returns a value and is assigned to the variable using the = assignment operator, what type is the variable assigned?
If an expression returns a value and is assigned to the variable using the = assignment operator, what type is the variable assigned?
Kotlin has a feature for calling a function without explicitly providing the arguments, even if the function expects them.
Kotlin has a feature for calling a function without explicitly providing the arguments, even if the function expects them.
Flashcards
Kotlin for Android Development
Kotlin for Android Development
Android mobile development now primarily uses Kotlin, improving developer productivity.
Kotlin Advantages
Kotlin Advantages
Kotlin offers cleaner code, reduced errors, Jetpack library support, multiplatform development, and strong community.
Kotlin's Hello World
Kotlin's Hello World
The basic Kotlin program to print "Hello, world!".
Kotlin Functions
Kotlin Functions
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Function Return Type
Function Return Type
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val
val
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var
var
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Type Inference
Type Inference
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String Interpolation
String Interpolation
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Variable Assignment
Variable Assignment
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Multiple Parameters in Functions
Multiple Parameters in Functions
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Classes and Instances
Classes and Instances
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Control Flow (if-else)
Control Flow (if-else)
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Control Flow (for Loops)
Control Flow (for Loops)
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Range (for Loops)
Range (for Loops)
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Kotlin Lists
Kotlin Lists
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Kotlin Arrays
Kotlin Arrays
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Kotlin: Null Safety
Kotlin: Null Safety
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Nullable Values
Nullable Values
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Type Checks & Automatic Casts
Type Checks & Automatic Casts
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Android Studio
Android Studio
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Study Notes
Android App Development: Kotlin Base
- Android mobile development has been Kotlin-first since Google I/O 2019.
- Over 50% of professional Android developers use Kotlin as their primary language.
- Only 30% use Java as their primary language.
- 70% of developers whose primary language is Kotlin find Kotlin more productive.
Benefits of Kotlin for Android
- Less code, greater readability.
- Fewer common errors.
- Kotlin support in Jetpack libraries.
- Support for multi-platform development.
- Mature language and environment.
- Easy learning.
- Large, active community.
Kotlin Playground
- An online tool for trying out and practicing Kotlin code.
- The code is sent to a JetBrains server for compilation.
Kotlin Basics
- The smallest Kotlin program prints "Hello, world!".
fun main() { ... }is the main function.println()is used to print output.
Defining and Calling Functions
- Use the keyword
funto define a function, followed by the name, parameters (if any), and return type (if any). - Function names use camel case convention.
- The code within the curly braces (
{}) is the function's body. - Functions are called by their name, followed by parentheses containing the arguments, if needed.
Function Return Types
- Some functions return values.
- The
returnkeyword is used to send a value back.
Variables
valdeclares immutable variables. Their values cannot change.vardeclares mutable variables. Their values can be modified.- Variables are given an initial value.
Type Inference
- Kotlin can infer the type of a value based on its initializer.
- The type must be specified if no initializer is provided.
Int,Double, etc are data types.
Functions with Multiple Parameters
- Functions can accept multiple parameters separated by commas.
- Each parameter has a specified data type.
Normal Function Call
- The function
sum()is called within themainfunction.
Creating Classes and Instances
classstatements define classes.- Variables within a class definition are called properties.
- Instances of a class can be created.
- Instances are created with specific values assigned to the properties of the class.
Control Flow: IF/ELSE Statements
if/elsestatements allow for conditional execution of code blocks.- Conditional statements use boolean expressions to allow or not allow the subsequent blocks.
Control Flow: Loops (for and Ranges)
- The
forloop iterates over a range of values. range(e.g.,1..5,5 downTo 1,3..6 step 2) defines a sequence of values.
Kotlin Collections (Lists)
listOf()creates immutable lists.mutableListOf()creates mutable lists, which can be changed after creation.arrayOf()creates arrays.- Arrays cannot change their size after creation.
Null Safety
- Kotlin variables aren't automatically null by default, avoiding common null pointer exceptions.
- Use
Int?for nullable integer variables. - The safe call operator (
?.) and the elvis operator (?:) are used to handle potential null values safely.
Type Checks and Automatic Casts
- The
isoperator checks if an expression is an instance of a certain type. - Kotlin can automatically cast certain types in some cases.
Android Studio
- A development environment for Android apps.
- The essential tools to create and run Android apps.
More
- Learn the Kotlin language. Learn syntax details in the included documentation
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