Android ondraw context issue when called from separate class

Question

I'm new to all this, and as you can probably tell by my question, I'm getting very spun in circles after reading all I could find on this. Please help.

I have a ClassA that contains an inner ViewClass that extends view. From ClassA, I call DialogCreator Class that extends ClassA and displays a dialog. From the dialog listview, you can select an item that needs the ViewClass to redraw. No matter how I send context, I get a null pointer context error.

ClassA constructor:

public class ClassA extends Basclass{ // Baseclass extends Activity
   public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      context = this;
   }

ClassA relevant code:

// Coming in from Menu for deleting or changing database tables
DialogCreator dc = new DialogCreator(context, id);
dc.onCreateDialog(title, list, mode);

    protected class ViewClass extends View{
         // Constructor
        public ViewClass(Context context){
             super(context); // Mainly crashes HERE
        }
           // Initializes rects, then draws via an OnDraw method
   }

DialogCreator constructor:

public class DialogCreator extends ClassA {
    DialogCreator(Context context, int dialogID){
     this.context = context;
     this.dialogID = dialogID;
}
}

Inside DialogCreator:

protected Dialog onCreateDialog(String title, final ArrayList list, final String mode) {
   // build alertdialog listView
   public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
       // User choices, etc... 
       ViewClass v = new ViewClass(context);
       setContentView(v); 
   }
}

Alternate OnCreateDialog would not try to setContentView... it calls a method in ClassA that tries to set it. Both fail.

I've tried passing the activity into DialogCreator, I've tried using the getXcontext() from both classes. I've even tried to stick a method in the ClassA that is called from DialogCreator class that uses the ClassA context. Clearly I am missing a very important understanding of context somewhere. Every way I try to define context, I crash with similar error as per LogCat below:

FATAL EXCEPTION: main
java.lang.NullPointerException
at android.app.Activity.startActivityForResult(Activity.java:3351)
at android.app.Activity.startActivityForResult(Activity.java:3312)
at android.app.Activity.startActivity(Activity.java:3522)
at android.app.Activity.startActivity(Activity.java:3490)

I'd be grateful for an unspin in the right direction.

Everything works perfectly if I keep all the code in the ClassA. Once I move the call to redraw into the DialogCreator, I get the context errors.

Answer 1

Took me all day, but found the answer thanks to Correct context to use within callbacks. @Vikram had it right in a somewhat related question about context in callbacks. The answer to my question was to use the original Activity's context by casting it.

((ClassA)context).methodToCall();

where methodToCall comes from the onItemClick() of DialogCreator, instead of calling the redraw directly.

I would never have figured out that casting.