Error message: "Attempt to use a non-final variable..."

Question

I get the following error message
"....java:771: Attempt to use a non-final variable rightColumn from a different method. From enclosing blocks, only final local variables are available.
          switchToOrderform4( backArrow_J, fwdArrow_J, rightColumn, c, jobticketEnclosure ); // ------- the problem line"
          ^
The variable is "rightColumn."
I instantiate it in one class, "Class1."
Pass it as a parameter to second class, "Class2."
Pass it as a parameter to a third class, "Class3."
Pass it as a parameter to a method, "method1( ... )."
-- Declared & instantiated here, passed as a parameter to
class Class1 extends JPanel {
     private JLabel rightColumn;
class Class2 extends MouseAdapter {
JLabel rightColumn,
--Passed as a method paramter, causing the compiler error (line 771):
class Class3 extends JPanel {
Line 75:      JLabel rightColumn;
Line 165:                          JLabel rightColumn,
Line 255:      this.rightColumn = rightColumn;
Line 771:           method1( backArrow_J, fwdArrow_J, rightColumn, c, jobticketEnclosure ); // ------- the problem line
Declaring the variables final does not help. How do I fix this?
Many thanks in advance.

Answer 1

Hmm that's a puzzler. I would love to see a complete (but minimal) example of this.
You might get more insight by using a different compiler, since you'd get a different version of the error message. Some compilers are more lucid than others.