Control flows are the basic building block of every programming language. What's different in Kotlin is that you can use a few of those control flows as an expression, such as try-catch, if-else, when, and so on. In this chapter, we will go through some of the control flows offered by Kotlin and learn to use them. Furthermore, we will also see how they provide much more power than Java control flows. So let's get started!

In Kotlin if is special because it returns values. That is why we can use an if statement to assign values to a result. This removes the need for a ternary operator in Kotlin. Let's see how we can use if statements to assign value.

You need to install a preferred development environment that compiles and runs Kotlin. You can also use the command line for this purpose, for which you need Kotlin compiler installed, along with JDK. I am using the command line for compiling and running my Kotlin code for this recipe.

In Kotlin, when is like a super-powered switch control statement. However, that's not all it can do. There's a lot of amazing logic that you can build with the when statement, one example of which is using a range with the when statement. We will take a look at that in this recipe.

You need to install a preferred development environment that compiles and runs Kotlin. You can also use the command line for this purpose, for which you need Kotlin compiler installed, along with JDK. I am using the command line to compile and run my Kotlin code for this recipe.

In Kotlin, when is already so powerful but did you know you can also use custom objects in when? Amazing, right? Let's go about implementing it.

You need to install a preferred development environment that compiles and runs Kotlin. You can also use the command line for this purpose, for which you need Kotlin compiler installed, along with JDK. I am using the command line to compile and run my Kotlin code for this recipe.

Create a file and name it whenWithObject.kt, and then, let's try when with a custom...

Exceptions in Kotlin are both similar and different compared to those in Java. In Kotlin, Throwable is the superclass of all the exceptions, and every exception has a stack trace, message, and an optional cause.

The structure of try–catch is also similar to that used in Java. In Kotlin, here's how a try–catch statement looks:

try {
 // some code to execute
 }
 catch (e: SomeException) {
 // exception handler
 }
 finally {
 // optional finally block 
 }

At least one catch block is mandatory and the finally block is optional, and so it can be omitted.

In Kotlin, try–catch is special as it enables it to be used as an expression. In this article, we will see how we can use try–catch as an expression.

Swapping two numbers is one of the most common things you do in programming. Most of the approaches are quite similar in nature: Either you do it using a third variable or using pointers.

In Java, we don't have pointers, so mostly we rely on a third variable.

You can obviously use something as mentioned here, which is just the Kotlin version of Java code:

var a = 1
var b = 2
run { val temp = a; a = b; b = temp }
println(a) // print 2
println(b) // print 1

However, in Kotlin, there is a very quick and intuitive way of doing it. Let's see how!

You need to install a preferred development environment that compiles and runs Kotlin. You can also use...

Sometimes, there are cases where you want to create your own exception. If you are creating your own exception, it's known as a custom exception or user-defined exception.

These are used to customize the exception according to a specific need, and using this, you can have your own exception and a message. In this recipe, we will see how to create and throw a custom exception in Kotlin.

You need to install a preferred development environment that compiles and runs Kotlin. You can also use the command line for this purpose, for which you need Kotlin compiler installed, along with JDK. I am using IntelliJ IDE to compile and run my Kotlin code for this recipe.

Conditional loops are common to any programming language you pick. If you apply multiple conditions on a loop, it is called a multiconditional loop. A simple example of a multiconditional loop in Java is illustrated here:

int[] data = {5,6,7,1,3,4,5,7,12,13};
 for(int i=0;i<10&&i<data[i];i++){
     System.out.println(data[i]);
 }

The preceding code on execution will print out 5, 6, and 7. Let's see how we can use a multiconditional loop in Kotlin. We will be looking at a functional approach to the same thing in Kotlin.

You need to install a preferred development environment that compiles and runs Kotlin. You can also use the command line for this purpose...