>From this perspective, protected is EXACTLY the same as public. Third party
apps can directly whack the value of the variable, at any time, without the
framework having any opportunity to do anything about it.
If there is a feature you need that isn't available in the public APIs, then
file a feature request. There will be no direct access to member variables
for apps to hack around the current implementation of the framework. (And
directly modifying mButtonResource is a perfect example of why it would be a
huge problem to allow this -- what if other member variables in the future
need to be set to match this? If you directly modify this, you could
completely break on a future version of the platform where the framework
doesn't have an opportunity to update its internal state appropriately.)
On Mon, Nov 30, 2009 at 8:39 PM, NoraBora <noranb...@gmail.com> wrote:
> I agree that Direct access to member variable is very bad.
>
> but how about protected?
>
> If all the variables are protected, people can extend and make their
> widget much more easily.
>
> For example I wanted to change the image alignment of RadioButton,
>
> so I tried to make MyRadioButton extends RadioButton(actually
> CompoundButton) and override onDraw..
>
> but mButtonResource is private so MyRadioButton can't get access to
> it.
>
> I think this discourages people from making custom widgets.
>
> On Dec 1, 8:47 am, Dianne Hackborn <hack...@android.com> wrote:
> > It does, because it means the application can change it at any time,
> without
> > the framework knowing this has happened. Direct access to member
> variables
> > is bad bad bad for maintenance.
> >
> >
> >
> > On Mon, Nov 30, 2009 at 2:50 PM, Taf <neild...@gmail.com> wrote:
> > > I'm not sure how 'hiding' the member vars in something like
> > > AdapterView makes it easier to maintain the platform. AdapterView just
> > > extends ViewGroup, so it would be straight forward for me to implement
> > > a copy of AdapterView just by extending ViewGroup, and then i could
> > > whack away at anything i wanted to. It seems to me that hiding the
> > > member vars in something like AdapterView doesn't give many advantages
> > > and just makes it harder to reuse existing code. Well anyhow, that's
> > > how it looks from over here.. :)
> >
> > > On Nov 30, 9:52 pm, Dianne Hackborn <hack...@android.com> wrote:
> > > > Member variables are implementation details. Exposing them for
> > > applications
> > > > to whack away on them as they want would make it much more difficult
> to
> > > > maintain the platform.
> >
> > > > On Mon, Nov 30, 2009 at 1:41 PM, Taf <neild...@gmail.com> wrote:
> > > > > OK a better example would be:
> >
> > > > > boolean mInLayout = false;
> >
> > > > > in AdapterView, this has no get or set function so it can only be
> > > > > accessed by classes in the same package such as Gallery with it's
> > > > > onLayout function:
> >
> > > > > protected void onLayout(boolean changed, int l, int t, int r, int
> > > > > b) {
> > > > > super.onLayout(changed, l, t, r, b);
> >
> > > > > /*
> > > > > * Remember that we are in layout to prevent more layout
> > > > > request from
> > > > > * being generated.
> > > > > */
> > > > > mInLayout = true;
> > > > > layout(0, false);
> > > > > mInLayout = false;
> > > > > }
> >
> > > > > I want to create a similar class to Gallery, but because my classes
> > > > > are not in the same package i cannot access mInLayout. even though
> I
> > > > > extend AbsSpinner and hence AdapterView,
> >
> > > > > so should mInLayout be protected? If it was i could then access it
> > > > > and write a similar custom class to Gallery..
> >
> > > > > On Nov 30, 9:01 pm, Taf <neild...@gmail.com> wrote:
> > > > > > Hi,
> >
> > > > > > I was just trying to extend the AbsSpinner Class, to create my
> own
> > > > > > custom widget. But the problem is that some of the member
> variables
> > > > > > have a a default scope, so I can't access them just by extending
> the
> > > > > > class (they can only be access directly by classes in the same
> > > > > > package). Some are ok as they have getters and setters , but
> there is
> > > > > > the odd member variable that doesn't , so i simply can't access
> them
> > > > > > because my new custom widget in not in the same package. An
> example
> > > of
> > > > > > such a member variable is mSelectedPosition in AdapterView.
> >
> > > > > > Would it not be better if these vars were to have a protected
> scope
> > > > > > rather than the default scope, it would then be easier to extend
> > > these
> > > > > > classes to make custom widgets outside of the package of these
> > > > > > classes.
> >
> > > > > --
> > > > > You received this message because you are subscribed to the Google
> > > > > Groups "Android Developers" group.
> > > > > To post to this group, send email to
> > > android-developers@googlegroups.com
> > > > > To unsubscribe from this group, send email to
> > > > > android-developers+unsubscr...@googlegroups.com<android-developers%2bunsubscr...@googlegroups.com>
> <android-developers%2bunsubscr...@googlegroups.com<android-developers%252bunsubscr...@googlegroups.com>
> ><android-developers%2Bunsubs
> > > cr...@googlegroups.com>
> > > > > For more options, visit this group at
> > > > >http://groups.google.com/group/android-developers?hl=en
> >
> > > > --
> > > > Dianne Hackborn
> > > > Android framework engineer
> > > > hack...@android.com
> >
> > > > Note: please don't send private questions to me, as I don't have time
> to
> > > > provide private support, and so won't reply to such e-mails. All
> such
> > > > questions should be posted on public forums, where I and others can
> see
> > > and
> > > > answer them.
> >
> > > --
> > > You received this message because you are subscribed to the Google
> > > Groups "Android Developers" group.
> > > To post to this group, send email to
> android-developers@googlegroups.com
> > > To unsubscribe from this group, send email to
> > > android-developers+unsubscr...@googlegroups.com<android-developers%2bunsubscr...@googlegroups.com>
> <android-developers%2bunsubscr...@googlegroups.com<android-developers%252bunsubscr...@googlegroups.com>
> >
> > > For more options, visit this group at
> > >http://groups.google.com/group/android-developers?hl=en
> >
> > --
> > Dianne Hackborn
> > Android framework engineer
> > hack...@android.com
> >
> > Note: please don't send private questions to me, as I don't have time to
> > provide private support, and so won't reply to such e-mails. All such
> > questions should be posted on public forums, where I and others can see
> and
> > answer them.
>
> --
> You received this message because you are subscribed to the Google
> Groups "Android Developers" group.
> To post to this group, send email to android-developers@googlegroups.com
> To unsubscribe from this group, send email to
> android-developers+unsubscr...@googlegroups.com<android-developers%2bunsubscr...@googlegroups.com>
> For more options, visit this group at
> http://groups.google.com/group/android-developers?hl=en
>
--
Dianne Hackborn
Android framework engineer
hack...@android.com
Note: please don't send private questions to me, as I don't have time to
provide private support, and so won't reply to such e-mails. All such
questions should be posted on public forums, where I and others can see and
answer them.
--
You received this message because you are subscribed to the Google
Groups "Android Developers" group.
To post to this group, send email to android-developers@googlegroups.com
To unsubscribe from this group, send email to
android-developers+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/android-developers?hl=en
