Re: Why must and must not be "final" ?

From:

"Daniel Pitts" <googlegroupie@coloraura.com>

Newsgroups:

comp.lang.java.programmer

Date:

13 Nov 2006 20:59:58 -0800

Message-ID:

<1163480397.936958.71030@b28g2000cwb.googlegroups.com>

NeoGeoSNK wrote:

Hello,
I have two questions, why inner class can only access "final" argument
outside the inner class?
and why Java applet's init() method can't access any "final" fields?
  example:
  public class AppletGui extends JApplet {
                          .........

               final JTextField textvalue;

                         ..........

          public void init(){
                         ..........

                        textvalue = new JTextField(25); //this will
encounter a compiled time error "the final field AppletGui.textvalue
can not be assigned
          }
  }

any suggestions are appreciated. ^ ^
Thanks
NeoGeoSnk

Its purely to reenforce to the programmer what really is happening.

The value of your parameters/variables which are used in your
anonymouse class are copied at the time that the object is created
(they are actually hidden final fields, I believe). If you were to
change the value later, that would be more confusing than having to
know that they are just "final".