如何在不扩展的情况下使用AppCompatActivity类？

Question

在这里，“ AttendanceListviewAdapter扩展了ArrayAdapter<attendanceContainer>”，但我想在此活动中设置警报。

但是如果不扩展AppCompatActivity类，我将无法做到这一点。有没有不扩展AppCompatActivity的方法，我可以在此活动中设置警报吗？

在这里要我提醒：

public class AttendanceListviewAdapter extends ArrayAdapter<attendanceContainer> {    
    TextView commonTextview;
    ImageButton mButton;

    public AttendanceListviewAdapter(Context context, int resource) {
        super(context, resource);
        }    
    public void openDialog(){
        alerth   alerthDilouge = new alerth();
        alerthDilouge.show(getSupportFragmentManager(), "exampledialog");
        //this code didn't works
       }
      }

#alerth class.....................

public class alerth extends AppCompatDialogFragment {
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        AlertDialog.Builder builder = new 
         AlertDialog.Builder(getActivity());

        //alerth code here already written

        return builder.create();
    }
}