Accessing activity from custom button

Question

Maybe I'm missing sth here but here it is. Let say I extended Button

    public class MyButton extends Button {
        ...
        public MyButton(Context context, AttributeSet attrs) {
            super(context, attrs);
            ...
        }
    }

If MyButton is in e.g. MyActivity I can simply cast context to activity.
Now if MyButton is part of MyDialog (extends Dialog), context.getClass() will point to ContextThemeWrapper and I can not get activity.

So how can I get instance of dialog or activity in the second case?

EDIT Ok more code to better illustrate what I wanted to do:

public class MyDialog extends Dialog {
    private MyButton myButton;

    public MyDialog(Context context) {
        super(context)  

        this.setContentView(R.layout.my_dialog);
        this.setTitle("My Dialog");

        myButton = (MyButton) findViewById(R.id.my_button);
    }
}

public class MyButton extends Button implements Command {
    private MyActivity myActivity;

    public MyButton(Context context, AttributeSet attrs) {
        super(context, attrs);

        System.out.println(context instanceof ContextThemeWrapper); // TRUE
        System.out.println(context instanceof Activity); // FALSE

        myActivity = ??? // or myDialog = ???
    }

    @Override
    public void execute() {
        MyDialog myDialog = myActivity.getMyDialog();
        myDialog.cancel();
    }

}

and somewhere in other class after connecting listener:

@Override
public void onClick(View v) {
    Command command = (Command) v;
    command.execute();
}

Please give some context for your question (no pun intended). What do you want to do with the dialog or activity instance? — Code-Apprentice, Oct 29 '12 at 20:56
For example MyButton can also implement Command interface with execute() method and in some external class I can have onClick() method with Command command = (Command) v; If I click the button, execute() method runs. I need to get to dialog instance from inside MyButton for example to close dialog. I'm just curious/playing after reading this: http://alvinalexander.com/java/java-command-design-pattern-in-java-examples — krisk, Oct 29 '12 at 21:17

score 20 · Answer 1 · answered Dec 12 '14 at 00:00

20

I had similar situation and I solve my case wit this snippet:

private static Activity scanForActivity(Context cont) {
    if (cont == null)
        return null;
    else if (cont instanceof Activity)
        return (Activity)cont;
    else if (cont instanceof ContextWrapper)
        return scanForActivity(((ContextWrapper)cont).getBaseContext());

    return null;
}

Hope that this can help somebody.

answered Dec 12 '14 at 00:00

kikea

1,569
1
13
14

plug and play thank you for that, and glad you did not use a switch statement which could cause exceptions – CrandellWS Feb 17 '16 at 15:15

Sam · Answer 2 · 2012-10-30T17:48:08.657

1

I'm don't fully understand what you are doing, but you should be able to get a reference to the Activity from your Dialog with getOwnerActivity().

Perhaps:

public MyButton(Context context, AttributeSet attrs) {
    super(context, attrs);

    Activity activity = getOwnerActivity();
    ...
}

edited Oct 30 '12 at 17:48

answered Oct 29 '12 at 20:55

Sam

86,580
20
181
179

Unfortunately it does not work. As for (Dialog) context cast, even Eclipse complains. For me it is strange that (Activity) context produces java.lang.ClassCastException: android.view.ContextThemeWrapper cannot be cast to android.app.Activity. Anyway thanks for reply. – krisk Oct 30 '12 at 17:39
You're right Dialog cannot be a cast to a Context because Dialog doesn't extend Context... But the `getOwnerActivity()` method should work (as long as you open the Dialog as the documentation suggests.) – Sam Oct 30 '12 at 17:50

Accessing activity from custom button

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