Questions and Answers
What is the first step in getting started with Kotlin development?
Which command is used to execute a function in Kotlin's REPL?
What is a necessary prerequisite before creating a new project in Kotlin?
In Kotlin, what does REPL stand for?
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Which of the following is the least likely step in the process of getting started with Kotlin?
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What is the range of values for the Int data type in Kotlin?
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What would be the result type of the operation 6.0 * 50?
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Which numeric type holds the largest range of values in Kotlin?
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How many significant digits can the Float type represent?
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Which of the following operations is not supported by the Boolean type in Kotlin?
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Study Notes
Getting Started with Kotlin
- Open IntelliJ IDEA and create a new project.
- Utilize REPL (Read-Eval-Print-Loop) to run Kotlin code.
- Create functions, such as
printHello(), and execute using Control+Enter (or Command+Enter on Mac).
Operators and Numeric Operations
- Kotlin treats numbers as primitives but allows method calls, e.g.,
2.times(3)returns 6. - Other methods:
-
3.5.plus(4)gives 7.5 -
2.4.div(2)yields 1.2
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Data Types in Kotlin
-
Integer Types:
- Long: 64 bits, range -2^63 to 2^63-1
- Int: 32 bits, range -2^31 to 2^31-1
- Short: 16 bits, range -32768 to 32767
- Byte: 8 bits, range -128 to 127
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Floating-point Types:
- Double: 64 bits, precision of 16-17 significant digits.
- Float: 32 bits, precision of 6-7 significant digits.
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Other Types:
- Char: 16-bit Unicode character
- Boolean: 8 bits, can be true or false.
Control Flow Structures
- For Loops: Simplifies iteration over collections without manual index management.
-
Sample Usage:
- Iterate over an array of pets with syntax
for (element in pets). - Access both index and element using
for ((index, element) in pets.withIndex()).
- Iterate over an array of pets with syntax
- While Loops: Useful for repeating actions until a condition is met. E.g., incrementing a counter within a limit.
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Repeat Loops: Execute a block of code a certain number of times, e.g.,
repeat(2) { print("Hello!") }.
Lists and Arrays
-
Lists:
- Ordered collections; allow duplicates.
- Immutable lists created using
listOf(), e.g.,val instruments = listOf("trumpet", "piano"). - Mutable lists created using
mutableListOf(), which allows element changes.
-
Arrays:
- Fixed-size collections that can store multiple items of the same or mixed types.
- Create arrays using
arrayOf(), e.g.,val pets = arrayOf("dog", "cat"). - Combine arrays with the
+operator, e.g.,val combined = numbers2 + numbers.
Null Safety
- By default, Kotlin variables cannot be null, preventing null-pointer exceptions.
- A variable can be declared nullable using
?, e.g.,var numberOfBooks: Int? = null. - Safe call operator (
?) checks for null before proceeding, and the Elvis operator (?:) can provide default values. - Avoid setting variables to null as it may lead to unwanted consequences.
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Description
Dive into the fundamentals of Kotlin with this first lesson in Android Development. Cover essential topics like data types, variables, operators, and null safety. Perfect for beginners looking to build a solid foundation in Kotlin programming.
