Been

public class Main3Activity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {
    List<HashMap<String,String>> fill_data;
    HashMap<String,String> myMap;
    SimpleAdapter myAdapter;

    ListView display;
    String fileName = "info.csv";
    BufferedReader buff;

    private static int id;
    private static string name;
    private static float weight;
    private static float height;
    private static float bmi;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main3);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        display = (ListView) findViewById(R.id.lstDiaplayBMI);

        myAdapter = null;
        String[] from = new String[]{"item1","item2","item3"};
        int[] to = new int[]{R.id.txtNo,R.id.txtName,R.id.txtBmi};

        myMap = new HashMap<String, String>();
        myMap.put("item1","No.");
        myMap.put("item2","Name");
        myMap.put("item3","BMI");
        fill_data.add(myMap);

        try {
            buff = new BufferedReader(new InputStreamReader(openFileInput(fileName)));

            String tmp;
            ArrayList<persons> personList = new ArrayList<persons>();
            while ((tmp = buff.readLine()) != null) {

                String[] arr = tmp.split(",");
                name = arr[0];
                weight = Float.parseFloat(arr[1]);
                height = Float.parseFloat(arr[2]);
                float m = hieght / 100;
                bmi = weight /( m *m );
                personList.add(new persons(name, weight, height, bmi))
            }
            buff.close();

//            myAdapter = new SimpleAdapter(Main3Activity.this, fill_data, R.layout.display3_layout, from, to);
//            display.setAdapter(myAdapter);

        }catch (Exception e){
            Toast.makeText(Main3Activity.this, "ERROR : "+ e.getMessage(),
                    Toast.LENGTH_LONG).show();
        }

    static ArrayList<persons> sort(ArrayList<persons> List) {
      persons tmp;
      for (int i = 1; i < List.size(); i++) {
        for (int j = 0; j < List.size() - i; j++) {
            if (List.get(j).bmi < List.get(j + 1).bmi) {
                 tmp = List.get(j);
                 List.set(j, List.get(j + 1));
                 List.set(j + 1, tmp);
            }
        }
      }
      return List;
     }
    static class persons {
        String name;
        float wieght;
        float hieght;
        float bmi;

        persons(String name, float wieght, float hieght, float bmi)
            this.name = name;
            this.wieght = wieght;
            this.hieght = hieght;
            this.bmi = bmi;
    }
}