Java file to connect to Arduino and get and plot the sensor data in line graph

ArduinoActivity.java

package me.ashif.smartrelay.activity;

import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.databinding.DataBindingUtil;
import android.hardware.usb.UsbDevice;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;

import com.anychart.AnyChart;
import com.anychart.AnyChartView;
import com.anychart.chart.common.dataentry.DataEntry;
import com.anychart.chart.common.dataentry.ValueDataEntry;
import com.anychart.charts.Cartesian;
import com.anychart.core.cartesian.series.Line;
import com.anychart.data.Mapping;
import com.anychart.data.Set;
import com.anychart.enums.Anchor;
import com.anychart.enums.MarkerType;
import com.anychart.enums.TooltipPositionMode;
import com.anychart.graphics.vector.Stroke;

import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import me.ashif.smartrelay.R;
import me.ashif.smartrelay.databinding.ActivityMainBinding;

public class MainActivity extends AppCompatActivity {

    private static final String ACTION_USB_PERMISSION = "usb_intent";
    private ActivityMainBinding mBinding;
    private UsbManager usbManager;
    private UsbDevice device;
    private Object connection;

    private final BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            if (intent.getAction().equals(ACTION_USB_PERMISSION)) {
                boolean granted =
                        intent.getExtras().getBoolean(UsbManager.EXTRA_PERMISSION_GRANTED);
                if (granted) {
                    connection = usbManager.openDevice(device);
                    serialPort = UsbSerialDevice.createUsbSerialDevice(device, connection);
                    if (serialPort != null) {
                        if (serialPort.open()) {
                            setUiEnabled(true);
                            serialPort.setBaudRate(9600);
                            serialPort.setDataBits(UsbSerialInterface.DATA_BITS_8);
                            serialPort.setStopBits(UsbSerialInterface.STOP_BITS_1);
                            serialPort.setParity(UsbSerialInterface.PARITY_NONE);
                            serialPort.setFlowControl(UsbSerialInterface.FLOW_CONTROL_OFF);
                            serialPort.read(mCallback);
                        } else {
                            System.out.println("serial port status : not open");
                        }
                    } else {
                        System.out.println("serial port status : NULL");
                    }
                } else {
                    System.out.println("no permission to access the serial port");
                }
            } else if (intent.getAction().equals(UsbManager.ACTION_USB_DEVICE_ATTACHED)) {
                setupArduinoConnection();
            } else if (intent.getAction().equals(UsbManager.ACTION_USB_DEVICE_DETACHED)) {
                serialPort.close();
            }
        };
    };

    UsbSerialInterface.UsbReadCallback mCallback = new UsbSerialInterface.UsbReadCallback() {
        @Override
        public void onReceivedData(byte[] arg0) {
            String data = null;
            try {
                data = new String(arg0, "UTF-8");

                // creates sensor data object as the new temperature
                // from the sensor is received and plots the graph for
                // the incoming value

                SensorData sensorData = new SensorData();
                sensorData.setTemperature(data);

                setupChart(sensorData);


            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mBinding = DataBindingUtil.setContentView(this, R.layout.activity_main);

        setupArduinoConnection();
        //setupChart();
    }

    private void setupArduinoConnection() {
        HashMap<String, UsbDevice> usbDevices = usbManager.getDeviceList();
        if (!usbDevices.isEmpty()) {
            boolean keep = true;
            for (Map.Entry<String, UsbDevice> entry : usbDevices.entrySet()) {
                device = entry.getValue();
                int deviceVID = device.getVendorId();
                if (deviceVID == 0x2341)
                {
                    PendingIntent pi = PendingIntent.getBroadcast(this, 0,
                            new Intent(ACTION_USB_PERMISSION), 0);
                    usbManager.requestPermission(device, pi);
                    keep = false;
                } else {
                    connection = null;
                    device = null;
                }

                if (!keep)
                    break;
            }
        }
    }

    private void setupChart(SensorData sensorData) {
        AnyChartView anyChartView = findViewById(R.id.any_chart_view);
        Cartesian cartesian = AnyChart.line();
        cartesian.animation(true);
        cartesian.padding(10d, 20d, 5d, 20d);
        cartesian.crosshair().enabled(true);
        cartesian.crosshair()
                .yLabel(true)
                .yStroke((Stroke) null, null, null, (String) null, (String) null);

        cartesian.tooltip().positionMode(TooltipPositionMode.POINT);

        cartesian.title("Temp in Deg v/s Time (sec)");

        cartesian.yAxis(0).title("Temperature in Degrees");
        cartesian.xAxis(0).labels().padding(5d, 5d, 5d, 5d);

        List<DataEntry> seriesData = new ArrayList<>();

        // Add the value in the chart for the new incoming data
        seriesData.add(new ValueDataEntry("0s", Integer.valueOf(sensorData.getTemperature())));

        Set set = Set.instantiate();
        set.data(seriesData);
        Mapping series1Mapping = set.mapAs("{ x: 'x', value: 'value' }");

        Line series1 = cartesian.line(series1Mapping);
        series1.name("Temperature");
        series1.hovered().markers().enabled(true);
        series1.hovered().markers()
                .type(MarkerType.CIRCLE)
                .size(4d);
        series1.tooltip()
                .position("right")
                .anchor(Anchor.LEFT_CENTER)
                .offsetX(5d)
                .offsetY(5d);


        cartesian.legend().enabled(true);
        cartesian.legend().fontSize(13d);
        cartesian.legend().padding(0d, 0d, 10d, 0d);

        anyChartView.setChart(cartesian);
    }
}