Why FINAL??

Question

Dear all,
I got this error:
"local variable threshold is accessed from within inner class; needs to be declared final"
Why does it have to be final and what's the effect of it?
Kevin

Answer 1

If you are familiar with C++, you can think of final as being similar to the "const" keyword. Basically, "final" is a gurantee you make to the compiler that the object you are declaring to be final will not be changed later on at some point in your code. The compiler will hold you to that gurantee by generating an error if you to attempt to change the value of an Object that was declared final.
You can also declare methods to be final. That has two effects:
1. it means the method cannot be overridden.
2. It allows the compiler to inline the method, which can be useful for small methods that are called a lot since it can increase performance.
However, don't go overboard using final. Because it has a drawback. Since objects declared as final can be inlined, it also means that if you later make changes to the object implementation, you will have to recompile all of your classes that use that object.