Essential Kotlin

Getting started with Kotlin
- Getting started with Kotlin
- Hello World
- Hello World using a Companion Object
- Hello World using an Object Declaration
- Main methods using varargs
- Compile and Run Kotlin Code in Command Line
- Reading input from Command Line
Extension Methods
- Extension Methods
- Potential Pitfall Extensions are Resolved Statically
- Top-Level Extensions
- Lazy extension property workaround
- Sample extending Java 7 Path class
- Sample extending long to render a human readable string
- Sample extending Java 8 Temporal classes to render an ISO formatted string
- 07Using extension functions to improve readability
- Extension functions to Companion Objects appearance of Static functions
- Extensions for easier reference View from code
Java 8 Stream Equivalents
- Java 8 Stream Equivalents
- Accumulate names in a List
- Collect example 5 - find people of legal age output formatted string
- Collect example 6 - group people by age print age and names together
- Counting items in a list after filter is applied
- Different Kinds of Streams 7 - lazily iterate Doubles map to Int map to String print each
- Different Kinds of Streams 3 - iterate a range of Integers
- Names of male members
- Group names of members in roster by gender
- Filter a list to another list
- Finding shortest string a list
- Different Kinds of Streams 2 - lazily using first item if exists
- Partition students into passing and failing
- Different Kinds of Streams 4 - iterate an array map the values calculate the average
- Different Kinds of Streams 5 - lazily iterate a list of strings map the values convert to Int find max
- Different Kinds of Streams 6 - lazily iterate a stream of Ints map the values print results
- Compute sum of salaries by department
- Group employees by department
- How streams work - filter upper case then sort a list
- Different Kinds of Streams 1 - eager using first item if it exists
- Compute sum of salaries of employee
- Convert elements to strings and concatenate them separated by commas
- Collect example 7a - Map names join together with delimiter
- Collect example 7b - Collect with SummarizingInt
Interfaces
- Interfaces
- Interface with default implementations
- Basic Interface
- Properties in Interfaces
- super keyword
- Conflicts when Implementing Multiple Interfaces with Default Implementations
Generics
- Generics
- Declaration-site variance
- Use-site variance
Functions
- Functions
- Function References
- Basic Functions
- Inline Functions
- Lambda Functions
- Functions Taking Other Functions
- Operator functions
- Shorthand Functions
Null safety
- Smart casts
- Assertion
- Nullable and Non-Nullable types
- Eliminate nulls from an Iterable and array
- Null Coalescing Elvis Operator
- Safe call operator
- Elvis Operator
Idioms
- Serializable and serialVersionUid in Kotlin
- Delegate to a class without providing it in the public constructor
- Use let or also to simplify working with nullable objects
- Use apply to initialize objects or to achieve method chaining
- Filtering a list
- Fluent methods in Kotlin
- Creating DTOs POJOsPOCOs
Enum
- Enum
- Initialization
- Functions and Properties in enums
- Simple enum
- Mutability
Reflection
- Reflection
- Referencing a class
- Inter-operating with Java reflection
- Referencing a function
- Getting values of all properties of a class
- Setting values of all properties of a class
Configuring Kotlin build
- Gradle configuration
- Using Android Studio
- Migrating from Gradle using Groovy script to Kotlin script
Conditional Statements
- Conditional Statements
- When-statement argument matching
- When-statement as expression
- Standard if-statement
- If-statement as an expression
- When-statement instead of if-else-if chains
- When-statement with enums
Loops
- Loops in Kotlin
- Looping over iterables
- Repeat an action x times
- Break and continue
- Iterating over a Map in kotlin
- Recursion
- While Loops
- Functional constructs for iteration
Logging
- logging in kotlin
- kotlin.logging
Annotations
- Declaring an annotation
- Meta-annotations
Class Inheritance
- Class Inheritance
- Basics the open keyword
- Inheriting fields from a class
- Inheriting methods from a class
- Overriding properties and methods
Arrays
- Generic Arrays
- Arrays of Primitives
- Extensions
- Iterate Array
- Create an array
- Create an array using a closure
- Create an uninitialized array
Vararg Parameters In Functions
- Vararg Parameters in Functions
- Basics Using the vararg keyword
- Spread Operator Passing arrays into vararg functions
Basic Lambdas
- Basic Lambdas
- Lambda as parameter to filter function
- Lambda passed as a variable
- Lambda for benchmarking a function call
Type-Safe Builders
- Type-Safe Builders
- Type-safe tree structure builder
Kotlin Caveats
- Calling a toString on a nullable type
JUnit
- Rules
Exceptions
- Catching exception with try-catch-finally
Strings
- String Equality
- String Literals
- Elements of String
- String Templates
Regex
- Idioms for Regex Matching in When Expression
- Introduction to regular expressions in Kotlin
Collections
- Collections
- Using list
- Using map
- Using set
Type aliases
- Type aliases
- Function type
- Generic type
Kotlin Android Extensions
- Kotlin Android Extensions
- Using Views
- Configuration
- Painfull listener for getting notice when the view is completely drawn now is so simple and awesome with Kotlins extension
- Product flavors
Visibility Modifiers
- Visibility Modifiers
- Code Sample
DSL Building
- DSL Building
- Infix approach to build DSL
- Overriding invoke method to build DSL
- Using operators with lambdas
- Using extensions with lambdas
Kotlin for Java Developers
- Kotlin for Java Developers
- Declaring Variables
- Quick Facts
- Equality Identity
- IF TRY and others are expressions not statements
Ranges
- Ranges
- Integral Type Ranges
- downTo function
- step function
- until function
RecyclerView
- RecyclerView in Kotlin
- Main class and Adapter
Singletons
- Singleton objects
- Use as repalcement of static methodsfields of java
- Use as a singleton
Delegated properties
- Delegated properties
- Observable properties
- Custom delegation
- Lazy initialization
- Map-backed properties
- Delegate Can be used as a layer to reduce boilerplate
Class Delegation
- Class Delegation
- Delegate a method to another class
Basics of Kotlin
- Basic examples
coroutines
- coroutines
- Simple coroutine which delays 1 second but not blocks
Contributors

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