//getting the list view
    ListView userListView = (ListView) findViewById(R.id.users_ListView);

    //creating an array to represnt what ever you want
    ArrayList<String> users = new ArrayList<>();
    for (int i = 0; i < 10 ; i++) {
        //populate the array
        String s = "user " + i;
        users.add(s);
    }
    //setting up adapter to the array
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, users);
    //connecting the list view to get the data to show from the adapter
    userListView.setAdapter(adapter);

    //changing the arrayList by adding or subtracting
    String s = "another user";
    users.add(s);

    //update the adapter and list view with this command
    adapter.notifyDataSetChanged();