List items = null;

if(false) {
  items = ...
}

for(int index = 0; index < items.size(); index++) {//Since items is null, the value 0 is used as defined above.
  Object obj = items.get(index);
}

Person person = null;

if(false) {
  person = ...
}

if(person.getAge() > 18) {
  //allow to vote (18 is the voting age in the U.S.A.)
}

It allow you to resonably ignore nulls when desired but still always have the opportunity to check them. This wouldn't be something that is always required but could be optionally set in the class or interface.

Note: It probably wouldn't be a good idea to do this to any class or interface in the Java core just because it would change how programs run but it would be useful if I could do this on new classes or interfaces that I make. I am also not suggesting the way the programmer would write the defaults so ignore the exact syntax that I used.