Why is “null” present in C# and Java?

Question

We noticed that lots of bugs in our software developed in C# (or Java) cause a NullReferenceException.

Is there a reason why \"null\" has even been included in the l

Answer 1

Besides ALL of the reasons already mentioned, NULL is needed when you need a placeholder for a not-yet created object. For example. if you have a circular reference between a pair of objects, then you need null since you cannot instantiate both simultaneously.

class A {
  B fieldb;
}

class B {
  A fielda;
}

A a = new A() // a.fieldb is null
B b = new B() { fielda = a } // b.fielda isnt
a.fieldb = b // now it isnt null anymore

Edit: You may be able to pull out a language that works without nulls, but it will definitely not be an object oriented language. For example, prolog doesn't have null values.