Re: reflection problem

From:

Daniel Pitts <googlegroupie@coloraura.com>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 25 Jul 2007 07:44:55 -0700

Message-ID:

<1185374695.261225.40180@g12g2000prg.googlegroups.com>

On Jul 25, 7:33 am, xar...@gmail.com wrote:

hi all, i got a problem with this bunch of code:

[CODE]
Manager boss = new Manager("Paul Brown", 1000, 500);

Class c = boss.getClass();

try
{
Field field = c.getField("bonus");

Integer newBonus = field.getInt(boss);
newBonus = newBonus + 200;
field.setInt(boss, newBonus);

}

catch(NoSuchFieldException nsfe)
{
System.out.println(nsfe.getMessage());
nsfe.printStackTrace();}

catch(IllegalAccessException iae)
{
System.out.println(iae.getMessage());
iae.printStackTrace();}

[/CODE]

i got a class Manager with a public (otherwise i'd get a
NoSuchFieldException) Integer bonus field. i'd like to modify it via
reflection, but i get an error at this point:

Integer newBonus = field.getInt(boss);

[CODE]Exception in thread "main" java.lang.IllegalArgumentException:
Attempt to get java.lang.Integer field "dynamicbinding.Manager.bonus"
with illegal data type conversion to int
at
sun.reflect.UnsafeFieldAccessorImpl.newGetIllegalArgumentException(Unknown
Source)
at
sun.reflect.UnsafeFieldAccessorImpl.newGetIntIllegalArgumentException(Unknown
Source)
at sun.reflect.UnsafeObjectFieldAccessorImpl.getInt(Unknown Source)
at java.lang.reflect.Field.getInt(Unknown Source)
at reflection.Main.main(Main.java:30)[/CODE]

illegal data type conversion to int? what does it mean? how can i fix
this? thank you all :)

getInt returns (int), where as your Bonus value is an Integer.

You can either change the type of your bonus to int, or you can use
Integer newBonus = (Integer)field.get(boss);

Although, I'm curious why you wish to use Reflection. If your project
is simply to learn more about reflection, thats fine, but usually
using reflection for this sort of thing is a Bad Idea (TM). Perhaps
if you shared your goal with the group, we could suggest a better way.