Graph(LineChart) and json

public class MainActivity extends AppCompatActivity {
public static LineChart lineChart;
 
    public static String dataParseGet = "";
    private static final String SAVE_AKTIVITY = "one other";
    public static ArrayList<String> as = new ArrayList<String>();
    public static TextView data, texterr;
    RadioButton myRadioButton;
    public ArrayList<SpinnerModel> CustomListViewValuesArr = new ArrayList<>();
    fetchDataHistory f = new fetchDataHistory();
    boolean b;
    CustomAdapter adapter;
    MainActivity activity = null;
    RequestQueue requestQueue;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        activity = this;
        setListData();
        // Connect by id
        Spinner SpinnerExample = (Spinner) findViewById(R.id.spinner);
        data = (TextView) findViewById(R.id.textt);
        texterr = (TextView) findViewById(R.id.texterr);
        final RadioGroup radioGroup = (RadioGroup) findViewById(R.id.radioGroup);
        //forPieChar();
        
 
        // For adapter spinner
        Resources res = getResources();
        adapter = new CustomAdapter(activity, R.layout.spinner_rows, CustomListViewValuesArr, res);
        SpinnerExample.setAdapter(adapter);
        requestQueue = Volley.newRequestQueue(getApplicationContext());
 
        
        // get data with fetchDataHistory  and lineChart connect by id
        fetchDataHistory process1 = new fetchDataHistory();
        process1.execute();
        lineChart= (LineChart) findViewById(R.id.lineChar);
        lineChart.setDragEnabled(true);
        lineChart.setScaleEnabled(false);
        
        
     
 
 
        SpinnerExample.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                int rgs_id = radioGroup.getCheckedRadioButtonId();
                myRadioButton = (RadioButton) findViewById(rgs_id);
 
                String s = myRadioButton.getText().toString();
                if (s.equals("USD")) {
                    b = true;
                } else {
                    b = false;
                }
                fetchData process = new fetchData(b, position);
                process.execute();
 
 
            }
 
            @Override
            public void onNothingSelected(AdapterView<?> parent) {
 
            }
        });
    }
    public void setListData() {
        String coy[] = {"Bitcoin", "Ethereum", "Ripple", "Bitcoin Cash", "Cardano", "Litecoin", "NEM", "Stellar", "IOTA", "NEO", "EOS", "Dash", "Monero", "TRON", "Bitcoin Gold", "Ethereum Classic", "ICON", "Qtum", "Lisk", "RaiBlocks"};
        for (int i = 0; i < coy.length; i++) {
            final SpinnerModel sched = new SpinnerModel();
            sched.setCompanyName(coy[i]);
            ;
            sched.setImage("image" + i);
 
            CustomListViewValuesArr.add(sched);
        }
    }
 
    public  void forPieChar(){
        lineChart= (LineChart) findViewById(R.id.lineChar);
 
      lineChart.setDragEnabled(true);
      lineChart.setScaleEnabled(false);
      ArrayList<Entry> yValues = new ArrayList<>();
      yValues.add(new Entry(1, 73f));
        yValues.add(new Entry(2, 75f));
        LineDataSet set1 = new LineDataSet(yValues, "Data Set 1");
        set1.setFillAlpha(110);
        ArrayList<ILineDataSet> dataSets = new ArrayList<>();
        dataSets.add(set1);
        LineData data =new LineData(dataSets);
        lineChart.setData(data);
    }
}

public class fetchDataHistory extends AsyncTask<Void, Void,Void> {
  
 
 
 
   
    String data ="";
 
    String singleParsed = "";
    String dataParse = "";
    LineData dataLine;
    @Override
    protected Void doInBackground(Void... voids) {
        try {
 
//String d = condition.getNamecript();
            URL url = new URL("https://min-api.cryptocompare.com/data/histoday?fsym=ETH&tsym=RUB&limit=250&aggregate=3&e=CCCAGG");
            HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
            InputStream inputStream = httpURLConnection.getInputStream();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
            String linetext = "";
            while (linetext!=null){
                linetext = bufferedReader.readLine();
                data = data + linetext;
            }
            int index1 = data.indexOf('[');
            int index3 = data.lastIndexOf(']'); //9
            String a1 = data.substring(index1--,++index3 );
            JSONArray JA  = new JSONArray(a1);
            for ( int i = index1; i <JA.length();i++){
 
                    JSONObject JO = (JSONObject) JA.get(i);
                    singleParsed = "" + JO.get("time") + "";
                    dataParse = dataParse + singleParsed;
 
 
 
 
            }
 
            ArrayList<Entry> yValues = new ArrayList<>();
            yValues.add(new Entry(1, 73f));
            yValues.add(new Entry(2, 75f));
            LineDataSet set1 = new LineDataSet(yValues, "Data Set 1");
            set1.setFillAlpha(110);
            ArrayList<ILineDataSet> dataSets = new ArrayList<>();
            dataSets.add(set1);
            dataLine =new LineData(dataSets);
 
 
 
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return null;
    }
 
    @Override
    protected void onPostExecute(Void aVoid) {
        super.onPostExecute(aVoid);
        MainActivity.lineChart.setData(dataLine);
    }
 
 }