Final in inner class

Question

I am trying to manually make a drawing program similar to this one
http://javafx.com/samples/Draw/
However I am running into issues involving inner classes and finals.
"local variable size is accessed from within inner class; needs to be declared final"
It wants me to make either SIZE or size a final. However once final, I can't change the variable.
I have often used the variable in a for loop to assign a value(though maybe it was a bad practice?) however I am not sure the best way to handle this.
Any suggestions?
Thanks!
int SIZE = 1; //somewhere else
        for( int size = 0 ; size < 5 ; size++){
              Circle circle = new Circle(D/Padding);
              circle.setOnMousePressed(new EventHandler<MouseEvent>(){
                  public void handle(MouseEvent me){
                      SIZE = size;
         );edit:
I am well aware this isnt neccesarily a javafx specific thing, but more of a general java poor programming knowledge.
I also know that the mouseadapter is an anonymous class and can only access final.
I am just looking for any suggestions on how to best handle this.
Edited by: namrog on Jul 5, 2011 10:51 AM
Edited by: namrog on Jul 5, 2011 10:59 AM

Answer 1

namrog wrote:
I am trying to manually make a drawing program similar to this one
http://javafx.com/samples/Draw/
However I am running into issues involving inner classes and finals.
"local variable size is accessed from within inner class; needs to be declared final"
It wants me to make either SIZE or size a final. However once final, I can't change the variable.Yes, that's the point. If a local variable is to be used by an instance of a nested class, that nested instance can live on long after the local variable goes out of scope. So it needs its own, separate copy of the variable. However, since, as far as we are concerned, there is only one variable, that variable needs to be final, so that there will not be issues with keeping the two copies' values coherent.
I have often used the variable in a for loop to assign a value(though maybe it was a bad practice?) however I am not sure the best way to handle this.
Any suggestions?Create a final variable and copy the value of your non-final variable to it.
int nonFinal =...;
final int theFinalCopy = nonFinal;
new Whatever() {
    void doStuff() {
      doSomething(theFinalCopy);
}