Question

I have this code:

MyClass object;

.... some code here where object may or may not be initialised...

if (object.getId > 0) {
    ....
}

Which results in a compile error: object may not have been initialised, which is fair enough.

Now I change my code to this:

MyClass object;

.... some conditional code here where object may or may not be initialised...

if (object != null && object.getId > 0) {
     ....
}

I get the same compile error! I have to initialise object to null:

MyClass object = null;

So what’s the difference between not initialising an object, and initialising to null? If I declare an object without initialisation isn’t it null anyway?

Thanks

Answer 1

• fields (member-variables) are initialized to null (or to a default primitive value, if they are primitives)
• local variables are not initialized and you are responsible for setting the initial value.