Can final parameters be qualified in some way to r

问题:

"Why are you doing this what is wrong with you?" notwithstanding, is there any way to accomplish this without changing the final method parameter name?

private Foo createAnonymousFoo(final Bar bar) {
    return new Foo() {
        private Bar bar = SomeUnknownScopeQualifier.bar;

        public Bar getBar() {
            return bar;
        }

        public void doSomethingThatReassignsBar() {
            bar = bar.createSomeDerivedInstanceOfBar();
        }
    };
}

Obviously without the doSomethingThatReassignsBar call, you wouldn't need the member Bar and so on. In this case, the simple fix is to change final Bar bar to something like final Bar startBar and then the assignment is fine. But out of curiosity, is it possible to specifically refer to the final Bar (Similar to the way you would say Super.this)?

回答1:

I think the answer to your question is "no". From the Java Language Specification:

A local variable (§14.4), formal parameter (§8.4.1), exception parameter (§14.20), and local class (§14.3) can only be referred to using a simple name (§6.2), not a qualified name (§6.6).

In other words, there's nothing you can replace SomeUnknownScopeQualifier with in your example code to make the assignment statement in the inner class refer to the formal parameter name.

回答2:

I think it's not possible to do that. Rename the involved variables or create an alias:

private Foo createAnonymousFoo(final Bar bar) {
  final Bar alias = bar; 
  return new Foo() {
    private Bar bar = alias;

    // ...
  };
}