track-app/app/src/main/java/com/journaldev/gpslocationtracking/MainActivity.java

package com.journaldev.gpslocationtracking;

import android.annotation.TargetApi;
import android.content.DialogInterface;
import android.content.pm.PackageManager;
import android.os.Build;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import java.util.ArrayList;

import static android.Manifest.permission.ACCESS_COARSE_LOCATION;
import static android.Manifest.permission.ACCESS_FINE_LOCATION;

public class MainActivity extends AppCompatActivity {


    private ArrayList<String> permissionsToRequest;
    private ArrayList<String> permissionsRejected = new ArrayList<>();
    private ArrayList<String> permissions = new ArrayList<>();

    private final static int ALL_PERMISSIONS_RESULT = 101;
    LocationTrack locationTrack;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        permissions.add(ACCESS_FINE_LOCATION);
        permissions.add(ACCESS_COARSE_LOCATION);

        permissionsToRequest = findUnAskedPermissions(permissions);
        //get the permissions we have asked for before but are not granted..
        //we will store this in a global list to access later.


        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {


            if (permissionsToRequest.size() > 0)
                requestPermissions(permissionsToRequest.toArray(new String[permissionsToRequest.size()]), ALL_PERMISSIONS_RESULT);
        }


        Button btn = (Button) findViewById(R.id.btn);


        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                locationTrack = new LocationTrack(MainActivity.this);


                if (locationTrack.canGetLocation()) {


                    double longitude = locationTrack.getLongitude();
                    double latitude = locationTrack.getLatitude();

                    Toast.makeText(getApplicationContext(), "Longitude:" + Double.toString(longitude) + "\nLatitude:" + Double.toString(latitude), Toast.LENGTH_SHORT).show();
                } else {

                    locationTrack.showSettingsAlert();
                }

            }
        });

    }


    private ArrayList<String> findUnAskedPermissions(ArrayList<String> wanted) {
        ArrayList<String> result = new ArrayList<String>();

        for (String perm : wanted) {
            if (!hasPermission(perm)) {
                result.add(perm);
            }
        }

        return result;
    }

    private boolean hasPermission(String permission) {
        if (canMakeSmores()) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                return (checkSelfPermission(permission) == PackageManager.PERMISSION_GRANTED);
            }
        }
        return true;
    }

    private boolean canMakeSmores() {
        return (Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP_MR1);
    }


    @TargetApi(Build.VERSION_CODES.M)
    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {

        switch (requestCode) {

            case ALL_PERMISSIONS_RESULT:
                for (String perms : permissionsToRequest) {
                    if (!hasPermission(perms)) {
                        permissionsRejected.add(perms);
                    }
                }

                if (permissionsRejected.size() > 0) {


                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                        if (shouldShowRequestPermissionRationale(permissionsRejected.get(0))) {
                            showMessageOKCancel("These permissions are mandatory for the application. Please allow access.",
                                    new DialogInterface.OnClickListener() {
                                        @Override
                                        public void onClick(DialogInterface dialog, int which) {
                                            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                                                requestPermissions(permissionsRejected.toArray(new String[permissionsRejected.size()]), ALL_PERMISSIONS_RESULT);
                                            }
                                        }
                                    });
                            return;
                        }
                    }

                }

                break;
        }

    }

    private void showMessageOKCancel(String message, DialogInterface.OnClickListener okListener) {
        new AlertDialog.Builder(MainActivity.this)
                .setMessage(message)
                .setPositiveButton("OK", okListener)
                .setNegativeButton("Cancel", null)
                .create()
                .show();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        locationTrack.stopListener();
    }
}