Kotlin is operator examples | Check variable is of an instance type
- Admin
- Sep 20, 2023
- Typescript
This tutorials explains about how to check variable type or instance of an class in Kotlin with example
Sometimes, We want to check runtime type of an class in Kotlin with examples. Kotlin provides is operator to check an instance of an class.
What is is operator in Kotlin?
is
operator used to check if given variable type is an instance of a given class type or not. This will very helpful for developers to know the type of the object at runtime.
is operator syntax
variable is class
variable is an Kotlin valid variables declared with either Primitive or Custom Class.
possible variables values are variables
, object variables, and strings
.
fun main() {
val msg = "Cloudhadoop";
println(msg is String) // true
val num=123;
println(num is Int) // true
}
Kotlin Check class name as an string
Kotlin provides class literal syntax to get name using reflection. variable::class returns an
variable::class.java.typeName:
returns java class type name
variable::class.simpleName
: It just returns class name
variable::class.qualifiedName
: It returns Kotlin Class Name.
Syntax
variable::class.simpleName
variable::class.qualifiedName
variable::class.java.typeName
Here is an example
fun main() {
val msg = "Cloudhadoop";
println(msg::class.java.typeName)
println(msg::class.simpleName);
println(msg::class.qualifiedName);
val num=123;
println(num::class.java.typeName)
println(num::class.simpleName);
println(num::class.qualifiedName);
}
Output:
java.lang.String
String
kotlin.String
int
Int
kotlin.Int
Kotlin Check variable is of interface or class
is operator checks an give variable implements an interface or check an instance of an class using is Operator
interface Animal {
fun eat()
}
class Lion : Animal {
override fun eat() {
}
}
fun main() {
val lion = Lion()
println(lion is Animal)
println(lion is Lion)
println(lion::class.java.typeName)
println(lion::class.simpleName);
println(lion::class.qualifiedName);
}
Output:
true
true
Lion
Lion
Lion
Conclusion
To sum up, Learned A Step by Step example for Kotlin checks type of or instance of operator in Kotlin with examples for primitive and interfaces and custom classes