In the above example, the program provides null as value as the casting result, what can I do with null value as Int type, Literally Nothing. LengthOfStringSafeCall('star-trek as well')įun lengthOfStringNormalMethod(str:String?) Elvis Operator with Smart Cast Operator :

LengthOfStringNormalMethod('I have never watched star-wars') Safe call operator calls the method / property only if the given object is not null, if the object is null then safe call operator will not give a call to the method or variable(property). and safe call operator helps the user to perform a null check and then call a method or call to property(aka variable). So, What is Safe Call Operator in Kotlin ? You might not be able to use if and else everywhere to check whether a value null or not and then to use the value, as shown in the last topic. You cannot call methods on the parameter you receive whether it is null or not You cannot assign this variable to any other non-nullable data type inside the method You cannot pass this value to any other method which accepts non-nullable parameters Kotlin Poses some restriction on function if they accept Nullable Parameter if you don't compare the value with null:

When the program has External java code.

When you call the NullPointerException explicitly to throw an exception.

Reasons for NullPointerException in Kotlin :

If you create a function with nullable type then without checking for null, you cannot access the methods.

Kotlin compiler finds the null value while passing the parameter and shows error

If we create a function with non-nullable type, then no matter what Kotlin will not allow passing a null value to that method.

Kotlin doesn't allow the function calls on a nullable variable because allowing function calls on a variable which possibly hold a null value, you find it in below example.

Normal data types don't allow you to store the null.

We have to add question mar at the end of the datatype to make it as Nullable.ĮG: String?, Int?, Float?. Nullable data types are also the same as Normal datatypes but these will accept the null values as well.

Kotlin optional to nullable