Kotlin Program Flow Control

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Questions and Answers

What will happen if you try to assign null to a non-nullable String variable in Kotlin?

The variable will be set to null.

The program will compile without errors.

An exception will be thrown at runtime.

Compilation will fail with an error. (correct)

In Kotlin, a variable declared as 'var str: String? = 'Hello'' can hold a null value.

True

What is the purpose of using a try-catch block in Kotlin?

To handle exceptions that may occur during program execution.

In the operation '10/0', the exception thrown is called an __________ exception.

Arithmetic Signup and view all the answers

Match the following Kotlin features with their descriptions:

Nullable type = Allows a variable to hold a null reference Try-catch block = A method for handling exceptions ArithmeticException = An error for invalid arithmetic operations FileReader = Reads data from a file Signup and view all the answers

What will be displayed if 'DivideOperation(10, 0)' is called?

Divide by zero exception occured Signup and view all the answers

Kotlin guarantees that once a variable is declared as non-nullable, it can later be changed to nullable.

False Signup and view all the answers

What do you need to add to a type declaration in Kotlin to allow it to hold a null value?

A question mark (?) Signup and view all the answers

What does the while loop do in the given program?

Counts up to a specified number Signup and view all the answers

The do...while loop executes its body at least once before evaluating the test expression.

True Signup and view all the answers

How does the for loop utilize the 'in' keyword?

To check membership within a range or collection. Signup and view all the answers

In Kotlin, exception handling uses the keywords , , and __.

try, catch, finally Signup and view all the answers

Match the following loop types with their characteristics:

while loop = Repeats while a condition is true do...while loop = Executes once before checking the condition for loop = Iterates over a collection or a range try-catch block = Handles exceptions that may occur Signup and view all the answers

Which statement about ranges in Kotlin is true?

They allow iterating through a specific set of numbers. Signup and view all the answers

The body of a while loop can be executed zero times if the condition is false initially.

True Signup and view all the answers

What is the output of the program that computes the sum of natural numbers from 1 to 100?

5050 Signup and view all the answers

What is the purpose of the when construct in Kotlin?

To match an argument against multiple branches Signup and view all the answers

The when construct in Kotlin requires a break statement to prevent fall-through behavior.

False Signup and view all the answers

What is the value returned by the expression 'when (day) { 5 -> "Thursday"; else -> "Unknown" }' if day is 6?

Unknown Signup and view all the answers

In order to use the when construct as an expression effectively, you must include an ______ clause.

else Signup and view all the answers

Match the following constructs with their descriptions:

when = Construct that matches a variable against multiple branches while = Loop that continues as long as a condition is true do..while = Loop that executes at least once before checking the condition else = Clause used to handle unspecified cases in control flow constructs Signup and view all the answers

Which of the following is NOT a feature of the when construct in Kotlin?

It requires a break statement to prevent fall-through Signup and view all the answers

The while loop in Kotlin functions differently than the while loop in Java.

False Signup and view all the answers

What would be the output of the following code snippet if the input is 42?

val message = when(response){ 42 -> "So long, and thanks for the all fish" else -> "Not what I'm looking for" }

So long, and thanks for the all fish Signup and view all the answers

Study Notes

Controlling Program Flow

Program statements are executed sequentially by default, one after the other, in a linear fashion.
There are constructs that can cause programs to deviate from this linear flow.
Some constructs cause the flow to fork or branch.
Other constructs cause the program flow to loop.

The `when` Statement

Kotlin does not have a switch statement, but it uses a when construct.
Its form and structure are similar to switch.
A simple example implements a when statement to find the day of the week using a Calendar instance.
The when matches the argument against all branches sequentially.
When a match is found, it doesn't continue to the next branch.
No break statement needed.
The when construct can also be used as an expression. Each branch's value becomes the return value of the expression. The else clause is required in this case.

How to Write Branches Inside the `when` Construct

An example demonstrates how to use a when statement with a variable to determine the answer to life.
The variable is initialized using input from the user.
The different branches are based on the value of the variable.
The example shows conditional branches, ranges and matching patterns.

The `while` Statement

while and do...while statements in Kotlin work similarly to those in Java.
These are statements, not expressions.
Code example provides a refresher on while loop usage.
A flowchart outlines the structure of a while loop.

Example of Compute sum of Natural Numbers

Python program example for computing the sum of natural numbers up to 100.

`do...while` Loop

The do...while loop executes the code block once before evaluating the loop condition.
The syntax in Kotlin follows the pattern of do { } while (condition).

Flowchart of `do`...`while` Loop

A flowchart visually depicts the workings of the do...while loop. The loop body runs first, then the expression is evaluated.

The Program below calculates the sum of numbers...

A program example to compute the sum of numbers entered by users until a 0 entry is made.
The code uses a do...while loop for this functionality. The user inputs numbers until they input 0.

`for` loops

Example uses a for loop to iterate through a string array of words created by splitting a string.

Ranges

If needing to work with numbers in for loops, Ranges are used in Kotlin.
Ranges are a type that represents an arithmetic progression of integers, created with rangeTo().
Example for loop with range from 1-10.

Exception Handling

Kotlin's exception handling is similar to Java's using try, catch, and potentially a finally block.
Kotlin simplifies this by using unchecked exceptions, making try...catch blocks optional.
The optional example shows reading a file and handling potential errors.

Kotlin program of using try-catch as an expression

This Kotlin program demonstrates performing an arithmetic operation and handling potential ArithmeticException exceptions using a try, catch block—useful for handling arithmetic errors.
This example shows using try/catch to handle exceptions during arithmetic and how this works in a simple program that takes user input and performs an arithmetic division.

Handling Nulls

When declaring a variable of type String, it cannot be directly set to null in Kotlin.
Null values can be handled using optional types and the safe-call operator.
Example demonstrates how to handle potential null values in a Kotlin program.

Safe Call Operator

Kotlin introduced a safe-call operator (?).
This operator can handle nullable types, performing the null check and avoiding potential errors caused by null values.

Examples

Kotlin example of checking for empty, blank, and null strings.

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Description

This quiz covers controlling program flow in Kotlin, focusing on the 'when' statement as an alternative to the traditional 'switch' statement. Understand how this construct allows for branching and looping within your program logic. Test your knowledge on using 'when' effectively to enhance program control.

Kotlin Program Flow Control

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Podcast

Questions and Answers

What will happen if you try to assign null to a non-nullable String variable in Kotlin?

In Kotlin, a variable declared as 'var str: String? = 'Hello'' can hold a null value.

What is the purpose of using a try-catch block in Kotlin?

In the operation '10/0', the exception thrown is called an __________ exception.

Match the following Kotlin features with their descriptions:

What will be displayed if 'DivideOperation(10, 0)' is called?

Kotlin guarantees that once a variable is declared as non-nullable, it can later be changed to nullable.

What do you need to add to a type declaration in Kotlin to allow it to hold a null value?

What does the while loop do in the given program?

The do...while loop executes its body at least once before evaluating the test expression.

How does the for loop utilize the 'in' keyword?

In Kotlin, exception handling uses the keywords ______, ______, and ______.

Match the following loop types with their characteristics:

Which statement about ranges in Kotlin is true?

The body of a while loop can be executed zero times if the condition is false initially.

What is the output of the program that computes the sum of natural numbers from 1 to 100?

What is the purpose of the when construct in Kotlin?

The when construct in Kotlin requires a break statement to prevent fall-through behavior.

What is the value returned by the expression 'when (day) { 5 -> "Thursday"; else -> "Unknown" }' if day is 6?

In order to use the when construct as an expression effectively, you must include an ______ clause.

Match the following constructs with their descriptions:

Which of the following is NOT a feature of the when construct in Kotlin?

The while loop in Kotlin functions differently than the while loop in Java.

What would be the output of the following code snippet if the input is 42? val message = when(response){ 42 -> "So long, and thanks for the all fish" else -> "Not what I'm looking for" }

Study Notes

Controlling Program Flow

The when Statement

How to Write Branches Inside the when Construct

The while Statement

Example of Compute sum of Natural Numbers

do...while Loop

Flowchart of do...while Loop

The Program below calculates the sum of numbers...

for loops

Ranges

Exception Handling

Kotlin program of using try-catch as an expression

Handling Nulls

Safe Call Operator

Examples

Studying That Suits You

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Description

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Overview of Kotlin Programming Language

Kotlin Functions and Project Setup

In Kotlin, exception handling uses the keywords , , and __.

What would be the output of the following code snippet if the input is 42?

val message = when(response){ 42 -> "So long, and thanks for the all fish" else -> "Not what I'm looking for" }

The `when` Statement

How to Write Branches Inside the `when` Construct

The `while` Statement

`do...while` Loop

Flowchart of `do`...`while` Loop

`for` loops