Android擷取GPS 計算速度

package com.example.myapplication;

import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.location.LocationProvider;
import android.os.Handler;
import android.provider.Settings;

import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

import java.util.LinkedList;

public class MainActivity extends AppCompatActivity implements LocationListener{
    private LocationManager locationManager;
    private double locationX;
    private double locationY;
    private double tmpX;
    private double tmpY;
    private LinkedList<Float> speedQueue;

    private TextView resultTextView;
    Handler handler;
    Runnable r;

    private static final long MIN_MILLI_SECONDS = 2000;
    private static final float MIN_METRE = 3;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        locationManager = (LocationManager)getSystemService(LOCATION_SERVICE);
        resultTextView = (TextView)findViewById(R.id.resultTextView);

        speedQueue = new LinkedList<>();
        speedQueue.add(0f);
        speedQueue.add(0f);
        speedQueue.add(0f);
        locationX = locationY = 0.0;

        final boolean gpsEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);

        if (!gpsEnabled) {

            Intent settingsIntent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            startActivity(settingsIntent);
        }

        try {
            locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, MIN_MILLI_SECONDS, MIN_METRE, this);
        } catch (SecurityException se) {
            showMessage("權限未開啟");
            finish();
        }


        handler = new Handler();
        r = new Runnable() {
            @Override
            public void run() {
                float[] result = new float[3];
                Location.distanceBetween(tmpX, tmpY, locationX, locationY, result);
                float distance = result[0];
                float speed = speedCalc(distance);
                resultTextView.setText(String.format("%.2f km/h", speed));

                tmpX = locationX;
                tmpY = locationY;

                handler.removeCallbacks(this);
                handler.postDelayed(this, 3000);
            }
        };
        handler.post(r);
    }

    public float speedCalc(float distance) {
        float speed = distance / 3f * 3.6f;
        if(speed > 500f) {
            speed = 0f;
        }
        speedQueue.remove();
        speedQueue.add(speed);
        float sum  = 0f;
        for(Float f: speedQueue) {
            sum += f;
        }
        float result = sum / speedQueue.size();
        return result;
    }

    @Override
    public void onLocationChanged(Location location) {
        locationX = location.getLatitude();
        locationY = location.getLongitude();
    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        switch (status) {
            case LocationProvider.AVAILABLE:
                Log.d("debug", "LocationProvider.AVAILABLE");
                break;
            case LocationProvider.OUT_OF_SERVICE:
                Log.d("debug", "LocationProvider.OUT_OF_SERVICE");
                break;
            case LocationProvider.TEMPORARILY_UNAVAILABLE:
                Log.d("debug", "LocationProvider.TEMPORARILY_UNAVAILABLE");
                break;
        }
    }

    @Override
    public void onProviderEnabled(String provider) {

    }

    @Override
    public void onProviderDisabled(String provider) {
        showMessage("申請權限");
    }
    public void showMessage(String msg) {
        Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
    }
}