Plotting Line Graph with JSON data, Android

Question

I\'m total beginner in Android development and I\'m doing app for class. My assigment is to display JSON data in application as text and graphs. I\'m using Retrofit 2 to dis

Answer 1

Here is your solution.

First you have to add in dependencies

dependencies{
  compile 'com.github.PhilJay:MPAndroidChart:v2.2.3'
  ....}

Now in your xml add below code

<com.github.mikephil.charting.charts.LineChart
                android:id="@+id/chart1"
                android:layout_width="match_parent"
                android:layout_height="match_parent" />

And now in your Java code

ArrayList<Entry> x;
ArrayList<String> y;
private LineChart mChart;
public String TAG = "YOUR CLASS NAME";

Inside onCreate Method

    x = new ArrayList<Entry>();
    y = new ArrayList<String>();
    mChart = (LineChart) view.findViewById(R.id.chart1);
    mChart.setDrawGridBackground(false);
    mChart.setDescription("");
    mChart.setTouchEnabled(true);
    mChart.setDragEnabled(true);
    mChart.setScaleEnabled(true);
    mChart.setPinchZoom(true);
    mChart.setMarkerView(mv);
    XAxis xl = mChart.getXAxis();
    xl.setAvoidFirstLastClipping(true);
    YAxis leftAxis = mChart.getAxisLeft();
    leftAxis.setInverted(true);
    YAxis rightAxis = mChart.getAxisRight();
    rightAxis.setEnabled(false);
    Legend l = mChart.getLegend();
    l.setForm(Legend.LegendForm.LINE);

Call this method on button click.

private void drawChart() {

    String tag_string_req = "req_chart";

    StringRequest strReq = new StringRequest(Request.Method.POST, "YOUR URL",
            new Response.Listener<String>() {

                @Override
                public void onResponse(String response) {

                    Log.d(TAG, "Response: " + response);

                    try {
                        JSONObject jsonObject = new JSONObject(response);
                        String id = jsonObject.getString("id");
                        JSONArray jsonArray = jsonObject.getJSONArray("measurements");
                        for (int i = 0; i < jsonArray.length(); i++) {

                            int value = jsonObject.getInt("value");
                            String date = jsonObject.getString("time");
                            x.add(new Entry(value, i));
                            y.add(date);

                        }
                        LineDataSet set1 = new LineDataSet(x, "NAV Data Value");
                        set1.setLineWidth(1.5f);
                        set1.setCircleRadius(4f);
                        LineData data = new LineData(y, set1);
                        mChart.setData(data);
                        mChart.invalidate();

                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }, new Response.ErrorListener() {

        @Override
        public void onErrorResponse(VolleyError error) {
            Log.e(TAG, "Error: " + error.getMessage());
        }
    });
    strReq.setRetryPolicy(new RetryPolicy() {

        @Override
        public void retry(VolleyError arg0) throws VolleyError {
        }

        @Override
        public int getCurrentTimeout() {
            return 0;
        }

        @Override
        public int getCurrentRetryCount() {
            return 0;
        }
    });
    strReq.setShouldCache(false);
    AppController.getInstance().addToRequestQueue(strReq, tag_string_req);
}

AppController code as here

public class AppController extends Application {
public static final String TAG = AppController.class.getSimpleName();
private RequestQueue mRequestQueue;
private static AppController mInstance;
@Override
public void onCreate() {
    super.onCreate();
    mInstance = this;
}

  public static synchronized AppController getInstance() {
    return mInstance;
}

public RequestQueue getRequestQueue() {
    if (mRequestQueue == null) {
        mRequestQueue = Volley.newRequestQueue(getApplicationContext());
    }
    return mRequestQueue;
}

public <T> void addToRequestQueue(Request<T> req, String tag) {
    req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
    getRequestQueue().add(req);
}
 }

Hope this will help you. If any issue faced let me know.