Android Development with Kotlin

The try... catch block

The Kotlin try... catch block is the equivalent of the Java try... catch block. Let's look at a quick example:

    fun sendFormData(user: User?, data: Data?) { // 1 
        user ?: throw NullPointerException("User cannot be null")         // 2 
        data ?: throw NullPointerException("Data cannot be null")         
     
        //do something 
    } 
 
    fun onSendDataClicked() { 
        try { // 3 
            sendFormData(user, data) 
        } catch (e: AssertionError) { // 4 
            // handle error 
        }  finally { // 5 
            // optional finally block 
        } 
    } 

1. Exceptions are not specified on function signature like in Java.
2. We check the validity of the data and throw NullPointerException (notice that no new keyword is required when creating an object instance).
3. The try... catch block is similar construct to Java.
4. Handle ...