What is the point of the finally block?

Question

Syntax aside, what is the difference between

try {
}
catch() {
}
finally {
    x = 3;
}

and

try {
}
catch() {
}

x = 3;

edit: in .NET 2.0?

---

so

try {
    throw something maybe
    x = 3
}
catch (...) {
    x = 3
}

is behaviourally equivalent?

Answer 1

Well, for one thing, if you RETURN inside your try block, the finally will still run, but code listed below the try-catch-finally block will not.

Answer 2

Depends on the language as there might be some slight semantic differences, but the idea is that it will execute (almost) always, even if the code in the try block threw an exception.

In the second example, if the code in the catch block returns or quits, the x = 3 will not be executed. In the first it will.

In the .NET platform, in some cases the execution of the finally block won't occur: Security Exceptions, Thread suspensions, Computer shut down :), etc.

Answer 3

In Java:

Finally always gets called, regardless of if the exception was correctly caught in catch(), or in fact if you have a catch at all.