Android studio listview need to be visible

Hi guys I am new to developing i need help with some codes. :) Hope you guys can help.

I am using Sqlite database i need to create a list view that display the word from database so hope you guys can help me. here is my code above. ty




//Code
public class Ortho extends ActionBarActivity {

private final String TAG = "Ortho";
DatabaseHelper dbhelper;
TextView word;
TextView mean;
AutoCompleteTextView actv;
Cursor cursor;
Button search;
int flag = 0;
ListView ls;
ArrayList<String> dataword;


@override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.ortho);

ls = (ListView) findViewById(R.id.mainlist);
ls.setVisibility(View.VISIBLE);
//need code here



dbhelper = new DatabaseHelper(this);
try {
dbhelper.createDataBase();
} catch (IOException e) {
Log.e(TAG, "can't read/write file ");
Toast.makeText(this, "error loading data", Toast.LENGTH_SHORT).show();
}

dbhelper.openDataBase();

word = (TextView) findViewById(R.id.word);
mean = (TextView) findViewById(R.id.meaning);



String[] from = {"english_word"};
int[] to = {R.id.text};
actv = (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView);
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, R.layout.singalline, null, from, to);


// This will provide the labels for the choices to be displayed in the AutoCompleteTextView
adapter.setCursorToStringConverter(new SimpleCursorAdapter.CursorToStringConverter() {
@override
public CharSequence convertToString(Cursor cursor) {

return cursor.getString(1);
}
});
adapter.setFilterQueryProvider(new FilterQueryProvider() {
@override
public Cursor runQuery(CharSequence constraint) {
cursor = null;
int count = constraint.length();
if (count >= 1) {
String constrains = constraint.toString();
cursor = dbhelper.queryr(constrains);

}

return cursor;
}
});