Main activity code triggering NPE:

public void notDoneTask(View view){
        ToDoList obj = new ToDoList();
        obj.notDoneTask(view);
    }

XML code that defines layout of each new todo item:

 <Button
        android:id="@+id/task_not_done"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="notDoneTask"
        android:text="X" />

    <TextView
        android:id="@+id/task_title"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_margin="8dp"
        android:layout_weight="1"
        android:text="Hello" />

    <Button
        android:id="@+id/task_done"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="doneTask"
        android:text="V" />