Question

Take a look that the following code snippet:

A a = null
try {
  a = new A();
} finally {
  a.foo();  // What happens at this point?
}

Suppose A’s constructor throws a runtime exception. At the marked line, am I always guaranteed to get a NullPointerException, or foo() will get invoked on a half constructed instance?

Answer 1

The code inside the try block contains two distinct operations:

1. Create a new A instance.
2. Assign the new instance to a variable named a.

If an exception is thrown in step 1, step 2 will not be executed.
Therefore, you will always get a NullPointerException.