Non-final variable inside an inner class - my nemisis

Question

I have an issue with accessing variables from an inner method. This structure seems to allow access to the text objects but not to the button object. This comes from a bit of example code that just illustrates a simple form window with text fields and buttons that read them.
At the start of the class I have text objects defined like this:
public class SimpleGUI extends Composite {
Text nameField;
Text junkField;
// Constructors come next, etc...
Later within this class there is a method to create some GUI stuff, and then to create a button and when pressed access and print the text to the console
protected void createGui(){
junkField = new Text(entryGroup,SWT.SINGLE); //Ross
junkField.setText("Howdy");
Button OKbutton = new Button(buttons,SWT.NONE);
OKbutton.setText("Ok");
OKbutton.addSelectionListener(
new MySelectionAdapter() {
public void widgetSelected(SelectionEvent e) {
System.out.println("Name: " + nameField.getText());
System.out.println("Junk: " + junkField.getText());
And that all works fine. So within the inner class, the object junkField can be accessed nicely.
However if I try to do the same with the button (I want to change the label on the button after it's pressed) I get errors for trying to access a non-final object in an inner class.
I tried to handle the button similar to the text, adding this after the text defs:
     Button myButton;
and under the println's in the inner class I wanted:
if OKbutton.getText.equals("OK") {  OKbutton.setText("NotOK")}
That's when I get an issue with "cannot refer to a non-final variable inside an inside class defined in a different method"
Now, if I move the button declaration into the createGui method, and declare it with "final Button myButton" it works.
Why does the button need different treatment than the text?
Is this a suitable method to make my button change it's label when pressed, or is this sloppy?

Answer 1

Button is a local variable. The anonymous inner class object you create can continue to exist after the method ends, but the local variables will not. Therefore, as the error message says, you must make that local button variable final if you want to refer to it inside the anon inner class. If it's final, a copy of its value can be given to the inner class--there's no need to treat it as "variable."