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Subject: RE: final variable value lost in anonynous inner class
Date: Thu, 2 Dec 2004 15:03:44 -0000
Message-ID: <5684A7E6FB10504393A2806C1F4C021005AF7F35@orion.qas.com>
Thread-Topic: final variable value lost in anonynous inner class
Thread-Index: AcTYf6lyxohqBGxUQ++nxUA02MH4UAAAG5pg
From: "Allistair Crossley" <Allistair.Crossley@QAS.com>
To: "Tomcat Users List" <tomcat-user@jakarta.apache.org>

this looks like a school assignment ;)

> -----Original Message-----
> From: Oliver Jonas [mailto:oliver@jonas.com]
> Sent: 02 December 2004 15:00
> To: tomcat-user@jakarta.apache.org
> Subject: JSP: final variable value lost in anonynous inner class
>=20
>=20
> Hi,
>=20
> =20
>=20
> I have the following test JSP (see below.) When I use the=20
> final variable
> obtained by class A inside an anonymous subclass of B the=20
> values are lost.
> However, if I define the final variables' values directly=20
> without using
> class A it works. Both cases work fine when using this as a=20
> normal Java
> class, so it seems related to JSP's or Tomcat.
>=20
> =20
>=20
> The catalina.out output is:
>=20
> =20
>=20
> 1/ str1=3Dstr1
>=20
> 1/ str2=3Dstr2
>=20
> 1/ i1=3D1234
>=20
> 1/ i2=3D1234
>=20
> 2/ str1=3Dnull
>=20
> 2/ str2=3Dstr2
>=20
> 2/ i1=3D0
>=20
> 2/ i2=3D1234
>=20
> a =3D=3D null
>=20
> =20
>=20
> This is Tomcat 4.1.30 with VM 1.4.2_06.
>=20
> =20
>=20
> =20
>=20
> Do you know what is wrong or how to bypass this?
>=20
> =20
>=20
> Thanks,
>=20
> Oliver.
>=20
> =20
>=20
> <%!
>=20
>             public static class A
>=20
>             {
>=20
>                         private String s;
>=20
>                         private int i;
>=20
>                        =20
>=20
>                         public A() {
>=20
>                                     s =3D "str1";
>=20
>                                     i =3D 1234;
>=20
>                         }
>=20
>                        =20
>=20
>                         public String getS() {
>=20
>                                     return s;
>=20
>                         }
>=20
>                        =20
>=20
>                         public int getI() {
>=20
>                                     return i;
>=20
>                         }
>=20
>             }
>=20
>            =20
>=20
>             public A getA() {
>=20
>                         return new A();
>=20
>             }
>=20
>                        =20
>=20
>             public static abstract class B
>=20
>             {
>=20
>                         public B()
>=20
>                         {
>=20
>                                     run();
>=20
>                         }
>=20
>                        =20
>=20
>                         public abstract void run();
>=20
>             }          =20
>=20
> =20
>=20
>             public B getB()
>=20
>             {          =20
>=20
>                         final A a =3D getA();
>=20
>                        =20
>=20
>                         final String str1 =3D a.getS();
>=20
>                         final String str2 =3D "str2";
>=20
>                        =20
>=20
>                         final int i1 =3D a.getI();
>=20
>                         final int i2 =3D 1234;
>=20
>                                                =20
>=20
>                         System.out.println("1/ str1=3D" + str1);
>=20
>                         System.out.println("1/ str2=3D" + str2);
>=20
>                         System.out.println("1/ i1=3D" + i1);
>=20
>                         System.out.println("1/ i2=3D" + i2);
>=20
>                        =20
>=20
>                         return new B()
>=20
>                         {
>=20
>                                     public void run()
>=20
>                                     {
>=20
>=20
>                                                 System.out.println("2/
> str1=3D" + str1);
>=20
>                                                 System.out.println("2/
> str2=3D" + str2);
>=20
>                                                =20
>=20
>                                                =20
> System.out.println("2/ i1=3D"
> + i1);
>=20
>                                                =20
> System.out.println("2/ i2=3D"
> + i2);
>=20
>                                                =20
>=20
>                                                 if(a =3D=3D null)
> System.out.println("a =3D=3D null");
>=20
>                                     }
>=20
>                         };
>=20
>             }
>=20
> %>
>=20
> =20
>=20
> <%      =20
>=20
>             getB();
>=20
> %>
>=20
> =20
>=20
>=20


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