Kotlin

public class NullUnSafe {
    public static void main(String[] args) {
        System.out.println(getName().length());
    }

    public static String getName(){
        return null;
    }
}

package net.println.kotlin

fun getName(): String?{
    return null
}

fun main(args: Array<String>) {
    println(getName()?.length)
}

public class TypeCast {
    public static void main(String[] args) {
        Parent parent = new Parent();
        System.out.println(((Child)parent).getName());

        if (parent instanceof Child){
            System.out.println(((Child) parent).getName());
        }
    }
}

fun main(args: Array<String>) {
    val parent : Parent = Child()
    if(parent is Child){
        println(parent.name)
    }
}