What is the best way of downcasting objects ?

Child class object can be assigned directly to Parent class reference variable.

When we assign parent object to child class reference, there may following use cases :

UC 1. Direct assignment - Compilation error

// Invalid way

void method(Parent parent) { 

    Child child = parent; // Compile time error

}

UC 2. Downcasting without instanceof check - May be OK or ClassCastException

// Risky way of downcasting

void method(Parent parent) { 

    Child child = (Child) parent; // OK or ClassCastException

}

UC 3. Downcasting with instanceof check - prevents ClassCastException

// Best way of downcasting

void method(Parent parent) { 

     if(parent instanceof Child){ 

          Child child = (Child) parent; // Downcast, if possible

     }

}