Java - final variables

Question

I know that once a final variable has a value assigned to it, it cannot be changed. However I just have a couple of questions regarding this:

• When I have a

Answer 1

You should initialize a static final variable either in a static initializer, or directly. So either

static final JButton button = new JButton();

or

static final JButton button;

static {
  button = new JButton();
}

The Java language specification has some more documentation about it: the section about final variables specifies why you get the compile error:

It is a compile-time error if a final variable is assigned to unless it is definitely unassigned (§16) immediately prior to the assignment.

and chapter 16 talks about the definite assignment