KotlinBooleans

Kotlin Booleans

Very often, in programming, you will need a data type that can only have one of two values, like:

• YES / NO
• ON / OFF
• TRUE / FALSE

For this, Kotlin has aBoolean data type, which can take the valuestrue orfalse.

Boolean Values

A boolean type can be declared with theBoolean keyword and can only take the valuestrue orfalse:

val isKotlinFun: Boolean = trueval isFishTasty: Boolean = falseprintln(isKotlinFun)   // Outputs trueprintln(isFishTasty)   // Outputs false

Just like you have learned with other data types in the previous chapters, the example above can also be written without specifying the type, as Kotlin is smart enough to understand that the variables are Booleans:

val isKotlinFun = trueval isFishTasty = falseprintln(isKotlinFun)   // Outputs trueprintln(isFishTasty)   // Outputs false

Boolean Expression

A Boolean expressionreturnsa Boolean value:true orfalse.

You can use a comparison operator, such as thegreater than (>) operator to find out if an expression (or a variable) is true:

val x = 10val y = 9
println(x > y) // Returns true, because 10 is greater than 9

Or even easier:

println(10 > 9) // Returns true, because 10 is greater than 9

In the examples below, we use theequal to (==) operator to evaluate an expression:

val x = 10;println(x == 10); // Returns true, because the value of x is equal to 10

println(10 == 15); // Returns false, because 10 is not equal to 15