Gdg dev fest 2107 to kotlin, with love
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Kotlin is the new kid on the block. We compare its language features to other popular languages such as Java and Python. We focus on how Kotlin constructs strike a balance between brevity, clarity, and type-safety.
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Gdg dev fest 2107 to kotlin, with love
- 1. To Kotlin, with L ve Ayman Mahfouz
- 2. Biography (boooooring!) - VP of Engineering at Webalo - Los Angeles based - UX4IIoT - 20 years of software development - PhD. in software engineering
- 3. Programming Languages Pascal C C++ Java Python C# Objective-C ActionScript Scala Ruby Octave JavaScript Go TypeScript Kotlin BASIC
- 4. Kotlin Arrives! - Paid little attention until Google I/O announcement. - Android Studio Canary 3. - Immediately fell in love - Strongly-typed - Brief - Expressive - Interoperable with Java - Growing support - Starts from where others ended (Java, Python, Go, Swift)
- 5. Brevity Null Safety Conditionals Smart Cast Lambdas Collections We will go through:
- 6. Brevity In Java, one would normally write this: With my background, I translated this into Kotlin verbatim: Not idiomatic but still shorter! Can you spot the omissions? ● No ; ● No “new” ● “override” is a modifier ● “:” not “implements” ● “public” is default ● Return type In Java one would typically write code like this:
- 7. Brevity Using “Single Expression Function” syntax Pass a lambda expression to a function that accepts a single-method interface
- 8. Brevity Omit parameter type Omit parameter name as well Eliminate left hand side completely Lambda expression only argument so we can eliminate the parenthesis Omit parameter type
- 9. Brevity to Kotlin ... From Java ... With love!
- 10. We will go through: Brevity Null Safety Conditionals Smart Cast Lambdas Collections
- 11. Null Safety The dreaded NPE Handle explicitly
- 12. Null Safety Handle via Java 8 Optionals - very verbose! Handle by convention: - Special member naming (IfAny) - Null checks in constructor - Hand-coded - AspectsOr let it throw! (pun intended)
- 13. Null Safety Kotlin safe navigation operator Compile-time language-enforced null safety Forced init Force null guard Allowing late init Conscious NPE
- 14. We will go through: Brevity Null Safety Conditionals Smart Cast Lambdas Collections
- 15. Conditionals I cringe when I see if statements that look like this Use the ternary operator please!
- 16. Conditionals In Kotlin, if statement is an expression Combined with single expression function shorthand So you can write a function like this
- 17. Conditionals I hate “Switch” statements! But I love “when” expressions! 1. No annoying “break” or even “case” 2. Match against any type 3. Switch variable can be of any type
- 18. We will go through: Brevity Null Safety Conditionals Smart Cast Lambdas Collections
- 19. Smart Cast In Java explicit cast is needed In Kotlin Smart Cast takes place automatically
- 22. Smart Cast Automatic cast to non-null
- 23. We will go through: Brevity Null Safety Conditionals Smart Cast Lambdas Collections
- 24. Lambdas Think of it as a “function literal” The function “Array” produces an array by applying a lambda
- 25. Lambdas Higher-order functions: functions that take other functions as arguments
- 26. Lambdas Closures: lambdas can access variables in their outer scope
- 27. We will go through: Brevity Null Safety Conditionals Smart Cast Lambdas Collections
- 29. Collections - Streaming Chaining lambda operations
- 30. Collections - Immutability In Java both mutable and immutable collections implement the same interface - Runtime error Kotlin uses different interfaces - Compile error