Question

I am using a simple text field alert dialog with a positive and a cancel button. I want to validate my alert dialog and prevent the done button from closing the AlertDialog if the input is invalid.

Is there any way short of creating a custom dialog to prevent the PositiveButton onClick() handler from closing the dialog if the validation fails?

class CreateNewCategoryAlertDialog {
    final EditText editText;
    final AlertDialog alertDialog;

    class PositiveButtonClickListener implements OnClickListener {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            String name = editText.getText().toString();
            if(name.equals("")) {
                editText.requestFocus();
                editText.setError("Please enter a name");
                // Some code to stop AlertDialog from closing goes here...
            } else {
                doSomethingUsefulWithName();
            }
        }
    }

    AlertDialog buildAlertDialog(Context context) {
        return new AlertDialog.Builder(context)
        .setTitle(context.getString(R.string.enter_name))
        .setMessage(context.getString(R.string.enter_name_msg))
        .setView(editText)
        .setPositiveButton(context.getString(R.string.done), new PositiveButtonClickListener())
        .setNegativeButton(context.getString(R.string.cancel), null).create();
    }
}

Answer 1

Here’s how I did it. Technically, it doesn’t technically keep the dialog open, it closes it momentarily and re-opens it, but the net result is the same.

class MyAlertDialog implements OnDismissListener, OnCancelListener {
    final private EditText editText;
    final private AlertDialog alertDialog;
    final private EventManager eventManager;
    final private CategorySelector categorySelector;

    private Boolean canceled;

    MyAlertDialog(Context context) {
        editText = new EditText(context);
        alertDialog = buildAlertDialog(context);
        alertDialog.setOnDismissListener(this);
        alertDialog.setOnCancelListener(this);
        show();
    }

    private AlertDialog buildAlertDialog(Context context) {
        return new AlertDialog.Builder(context)
        .setTitle(context.getString(R.string.enter_name))
        .setMessage(context.getString(R.string.enter_name))
        .setView(editText)
        .setNeutralButton(context.getString(R.string.save_text), null)
        .setNegativeButton(context.getString(R.string.cancel_text), null)
            .create();
    }

    public void show() {
        canceled = false;
        alertDialog.show();
    }

    @Override public void onDismiss(DialogInterface dialog) {
        if(!canceled) {
            final String name = editText.getText().toString();
            if(name.equals("")) {
                editText.setError("Please enter a non-empty name");
                show();
            } else {
                doWhateverYouWantHere(name);
            }
        }
    }

    @Override public void onCancel(DialogInterface dialog) {
        canceled = true;
    }
}