Is it acceptable to use exceptions instead of verbose null-checks?

Question

I recenly encountered this problem in a project: There\'s a chain of nested objects, e.g.: class A contains an instance variable of class B, which in turns has an instance v

Answer 1

It's bad practice to use Exceptions here.

There's a hint in the name: Exceptions are for exceptional circumstances (i.e. unexpected) . If nulls are expected values, then encountering them is not exceptional.

Instead, I'd have a look at the class hierarchy and try to understand why such deep access chaining needs to happen. This seems like a big design issue, you shouldn't normally expect the caller to construct calls using deep knowledge of the structure of objects hidden within class A.

Questions you could ask:

• Why does the caller need to doSomething() with the Z object anyway? Why not put the doSomething() on class A? This could propagate doSomething() down the chain if needed and if the relevant field was not null....
• What does a null mean if it exists in this chain? The meaning of a null will suggest what business logic should be employed to handle it.... which could be different at each level.

Overall, I suspect the right answer is to put doSomething() on each level of the heirarchy and have the implementation something like:

class A {
  ...
  public void doSomething() {
    B b=getB();
    if (b!=null) {
      b.doSomething();
    } else {
      // do default action in case of null B value
    }
  }
}

If you do this, then the API user only has to call a.doSomething(), and you have the added bonus that you can specify different default actions for a null value at each level.