simple_list_item_1 can not be resolved or not a field

I am beginner in android ,I make a simple array list. and bind it to listview my code is

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    final EditText textbox1=(EditText)findViewById(R.id.editText1);
    ListView listview1=(ListView)findViewById(R.id.listView1);
    String[] items={"a1","a2","a3","a4","a5","a6","a7","a8","a9","a10"};
    final ArrayList<String> todo=new ArrayList<String>();
    final ArrayAdapter<String> aa;
    aa=new ArrayAdapter<String>(this, R.layout.simple_list_item_1,items);
    listview1.setAdapter(aa);
}

I am getting error in simple_list_item_1 I search on google but all the exmples tell only way to bind not why this error comes.