Map opens before picking up the GPS position

Question

I’m studying programming for Andriod and I came across a feature that I just don’t know anything, which is the order of execution of the duties! please , someone could give a light?

I explain, in my example I call the
- API to communicate with GPS, (line 90)
- THEN to effectively catch the position (latitude and longitude) (line 103)
- and then I call the map ! (line 210)

But I don’t know why, he opens the map BEFORE picking up the position of the GPS, that is, the map has no position to open and error.

Since I’m new, I don’t know exactly if I was clear... I hope you help me to understand and explain. I arrived here after much search, but I stopped because I don’t know how to open the map AFTER the consultation of the position...

Here’s the code I’m working on!

package jp.co.e_grid.rakuseki;

import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Location;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;

//import java.util.concurrent.atomic.DoubleAccumulator;

import io.realm.Realm;
import io.realm.RealmConfiguration;
import jp.co.e_grid.rakuseki.model.Report;

import static jp.co.e_grid.rakuseki.config.Constants.MAP_ZOOM;


/**
 * Created by ootaegd on 2016/12/16.
 */

public class PostPositionActivity extends AppCompatActivity
        implements OnMapReadyCallback, GoogleApiClient.OnConnectionFailedListener, GoogleApiClient.ConnectionCallbacks {

    private GoogleMap map;
    private Marker marker = null;
    private LatLng locationLatLng;
    //private static final LatLng MATSUE = new LatLng(35.47222, 133.05056); //マーカ初期値
    //private LatLng locationLatLng = instantPosition;
    private float accuracy;
    //private static final LatLng instantPosition = new LatLng(35.3852243, 132.7339911);  //              izumo
    //private static final LatLng instantPosition = new LatLng(35.47222, 133.05056);      //マーカ初期値  matsue
    private String uuId;
    //private LatLng instantPosition;
    protected Realm realm;
    private TextView tvCoordinate;
    private GoogleApiClient mGoogleApiClient;

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

        //前のactivityから渡されたデータを取得する
        Intent intent = getIntent();
        uuId = intent.getStringExtra("uuId");

        //realm設定
        Realm.init(this);
        RealmConfiguration config = new RealmConfiguration.Builder().build();
        Realm.setDefaultConfiguration(config);

        //toolbarを設定
        Toolbar toolbar = (Toolbar) findViewById(R.id.post_position_toolbar);
        toolbar.setTitle(getString(R.string.headPositionTitle));
        setSupportActionBar(toolbar);

        onBtnGpsClicked();
        nextViewActivity();

        //Fragment を取得
        MapFragment mapFragment = (MapFragment) getFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);

        tvCoordinate = (TextView) findViewById(R.id.tv_coordinate);
        callConnection();
    }

    /**
     * Getting the Google GPS API OnLine.
     *(linha 90)
     */
    private synchronized void callConnection() {
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addOnConnectionFailedListener(this)
                .addConnectionCallbacks(this)
                .addApi(LocationServices.API)
                .build();
        mGoogleApiClient.connect();
        Log.e("--------MESSAGE--------"," API loaded 01");
    }

    /**
     * Getting the actual GPS position.
      *(linha 103)
     */
    @Override
    public void onConnected(Bundle bundle) {

        if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //    ActivityCompat#requestPermissions
            // here to request the missing permissions, and then overriding
            //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
            //                                          int[] grantResults)
            // to handle the case where the user grants the permission. See the documentation
            // for ActivityCompat#requestPermissions for more details.
            return;
        }
        Location l = LocationServices
                .FusedLocationApi
                .getLastLocation(mGoogleApiClient);

        if(l != null){
            //tvCoordinate.setText(l.getLatitude()+" -- "+l.getLongitude()+"-----"+ l.getAccuracy());
            tvCoordinate.setText("Accuracy = "+ l.getAccuracy());
            accuracy = l.getAccuracy();
            Log.e("--------LOG--------", "latitude:  " + l.getLatitude());
            Log.e("--------LOG--------", "longitude: " + l.getLongitude());
            Log.e("--------LOG--------", "accuracy:  " + accuracy);
            // tvCoordinate.setText(" ||| "+l.getLatitude()+" ||| "+l.getLongitude()+" ||| ");
            // final LatLng instantPosition = new LatLng(35.3852243, 132.7339911); //izumo
            // final LatLng instantPosition = new LatLng(35.47222, 133.05056); // matsue
            locationLatLng = new LatLng(l.getLatitude(), l.getLongitude());
            //instantPosition = new LatLng(l.getLatitude(), l.getLongitude());
            Log.e("--------MESSAGE--------"," GPS get ok 02");
        }
    }

    @Override
    public void onConnectionSuspended(int i) {

    }

    /**
     * 次の画面へ遷移する処理
     */
    private void nextViewActivity() {
        //位置情報ボタンを押された時の処理
        Button btnPost = (Button) findViewById(R.id.btnPost);
        btnPost.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                //位置情報を追加する
                addReport();

                // 画面を起動
                Intent intent = new Intent();
                intent.setClassName("jp.co.e_grid.rakuseki", "jp.co.e_grid.rakuseki.PostConfirmationActivity");
                intent.putExtra("uuId",uuId);
                startActivity(intent);
            }
        });
    }

    /**
     * 現在地取得ボタンを押された時、現在地を取得する
     */
    private void onBtnGpsClicked() {
        Button btnPost = (Button) findViewById(R.id.btnLocation);
        btnPost.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                //現在地取得
            }
        });
    }

    /**
     * GoogleMapを読み込む前に、オーバライドして処理を行う
     *
     * @param googleMap
     *(linha 210)
     */
    @Override
    public void onMapReady( GoogleMap googleMap ) {
        map = googleMap;

        Log.e("--------MESSAGE--------"," original get 03");
        // final LatLng instantPosition = new LatLng(35.3852243, 132.7339911); // izumo
        // final LatLng instantPosition = new LatLng(35.47222,   133.05056);   // matsue
        //locationLatLng = new LatLng(35.47222,   133.05056);   // matsue  //test
        setMarker(locationLatLng);

        // GoogleMapが押下された時の処理
        googleMap.setOnMapClickListener(new GoogleMap.OnMapClickListener() {
            @Override
            public void onMapClick( LatLng latLng ){
                // クリックされるたびにマーカが増えていく
                // 一つ前のマーカは削除する
                marker.remove();
                //Mapが押下されたらその位置にピンを立てる
                //緯度経度を取得
                locationLatLng = latLng;
                //ピンを立てる
                setMarker(locationLatLng);
            }
        });
    }


    /**
     * Markerを立てる関数
     *
     * @param lacation　緯度経度情報
     */
    private void setMarker(LatLng lacation){
        marker = map.addMarker(new MarkerOptions()
                .position(lacation)
                .title("報告場所")
                .draggable(false));
        map.moveCamera(CameraUpdateFactory.newLatLngZoom(lacation, MAP_ZOOM));
    }

    /**
     * 位置情報を追加する
     * @return プライマリキー
     */
    private void addReport(){

        realm = Realm.getDefaultInstance();
        //トランザクション開始
        realm.beginTransaction();

        //uuIdでターゲットを抽出
        Report report = realm.where(Report.class).equalTo("key",uuId).findFirst();
        //保存を行う
        report.setLat(Double.parseDouble(String.valueOf(locationLatLng.latitude)));
        report.setLon(Double.parseDouble(String.valueOf(locationLatLng.longitude)));
        report.setAccuracy(Double.parseDouble(String.valueOf(accuracy)));
        Log.e("--------MESSAGE--------", " Longitude 04 " + String.valueOf(report.getLon()));
        Log.e("--------MESSAGE--------", " Latitude 04 "  + String.valueOf(report.getLat()));
        Log.e("--------MESSAGE--------", " Accuracy 04 "  + String.valueOf(report.getAccuracy()));

        //トランザクション終了
        realm.commitTransaction();
    }

    @Override
    public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {

    }
}

Answer 1

The order of execution of methods is the order in which they are called and not the order in which they are declared.

The order as you’re doing is ask to be created the map and then ask to be created the location service:

...
//Cria o mapa
mapFragment.getMapAsync(this);

...
//Cria o serviço de localização
callConnection();

I used ask to be created, instead of just create, because both methods return before the map and the service are created, the creation is asynchronously processed.

The fact that the methods are called in that order does not guarantee that the result of each processing ends in the same order.

Normally asynchronous processing uses callbacks to inform the calling code of the processing result.

The method getMapAsync(), of Mapfragment, uses an interface implementation Onmapreadycallback, passed as argument.

The method connect() uses implementations of GoogleApiClient.OnConnectionFailedListener and GoogleApiClient.ConnectionCallbacks, informed when constructing the object Googleapiclient.

How do you not know which one callbacks will be called first if onConnected() or onMapReady(), it is necessary (try)to put the Marker on the map in both methods.

In the method onConnected():

if(map != null){
    setMarker(locationLatLng);
}

In the method onMapReady():

if(locationLatLng != null){
    setMarker(locationLatLng);
}