If you plan to define a variable with no initial instantiation (value), you must place the type after the variable name: var s: Int The reason for using null is outside the scope of this article, but it's important to know that a variable can only equal null when explicitly defined to do so. This means the assigned value can be equal to null.

There are also nullable assignments that use syntax like: var f: Int? = 9

Each variable's type is optional because the type can be inferred, similar to the dynamic assignment in JavaScript. There's a subtle and important difference between var and val assignments: var is used when the variable you defined can be reassigned, and val is used for local scope values that will not be changed. Here are a few examples of creating basic integers: var I = 5 If you want to follow along and learn some of the language's features, there is a great browser-based Kotlin playground you can use. To introduce you to Kotlin, I will go over some of its basic syntax, ranging from variables to defining functions and classes. That immense investment in compatibility means if you come from a Java background, picking up Kotlin will feel familiar and be a low risk since it will run alongside any of your existing Java code. Standard Java code can be included in a Kotlin program, and Kotlin can be included in a Java program. The great news for Java developers is that Kotlin is interoperable with Java. JetBrains led its implementation, which began in 2010, and it has been open source since early in its development. Kotlin is a cross-platform, general-purpose programming language that runs on the Java Virtual Machine (JVM).

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