[tssg-tech] Re: Android "context" question
- From: Jim Cant <cant_jim@xxxxxxxxxxx>
- To: tssg tech <tssg-tech@xxxxxxxxxxxxx>
- Date: Sun, 14 Nov 2010 10:34:36 -0500
This might be an inner class issue rather than a Context issue.
Off the top of my head, it seems as if there might be to 'this'es in the scope
of the instance of the inner class. One this would be for the instance of the
inner class itself and the other this would be for the instance of the outer
containing class.
You might try logging the values for these possibilities to see how they behave
and are related. The hashCode() method will give you a value for an object
that's sorta, kinda, like the 'this pointer' in the C++ world.
Cheers,
jim
From: pn@xxxxxxxxx
To: tssg-tech@xxxxxxxxxxxxx
Subject: [tssg-tech] Android "context" question
Date: Sun, 14 Nov 2010 10:14:07 -0500
Can someone point me to a good tutorial on
Android context? As a noob,
there’s obviously something I’m not getting about it.
Recently I wrote a program were I defined
a Listener class within my Activity class (named Pdj) – so I had a class
within a class. In the inner class I tried to create an ArrayAdapter thusly:
ArrayAdapter<String> aa = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1,
todoArrayList);
But I got a build eror "The constructor
ArrayAdapter(Pdj.ButtonListener, int, ArrayList) is undefined"
The solution was to qualify my “this”
thusly:
ArrayAdapter<String> aa = new ArrayAdapter<String>(Pdj.this,
android.R.layout.simple_list_item_1,
todoArrayList);
Why is it necessary to qualify the context
here? The inner class object is invoked from the outer class and the inner
class can see and use member variables of the outer class. Not only that but
the error message The constructor
ArrayAdapter(Pdj.ButtonListener,
int, ArrayList) is undefined implies that the
compiler recognizes that the current class is part of Pdj! So obviously
there’s something about context I’m not getting.
Thanks in advance.
Peter Nelson
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