Android App Development: Languages, IDE, and GPS Bus Time Example

The primary programming language used for developing Android apps is Java. However, Kotlin has gained popularity as an alternative language for Android development.

The integrated development environment (IDE) used for Android app development is Android Studio, which is an official IDE provided by Google.

Here is a sample code for an Android app that uses GPS to check bus time:

import android.Manifest;
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.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.model.LatLng;

public class MainActivity extends AppCompatActivity implements GoogleApiClient.ConnectionCallbacks,
        GoogleApiClient.OnConnectionFailedListener, com.google.android.gms.location.LocationListener {

    private static final int MY_PERMISSIONS_REQUEST_LOCATION = 99;
    private GoogleApiClient mGoogleApiClient;
    private Location mLastLocation;
    private LocationRequest mLocationRequest;
    private TextView mTextView;

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

        mTextView = findViewById(R.id.textView);

        if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
                != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                    MY_PERMISSIONS_REQUEST_LOCATION);
        } else {
            buildGoogleApiClient();
        }
    }

    protected synchronized void buildGoogleApiClient() {
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
        mGoogleApiClient.connect();
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode) {
            case MY_PERMISSIONS_REQUEST_LOCATION: {
                if (grantResults.length > 0
                        && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    buildGoogleApiClient();
                } else {
                    Toast.makeText(this, 'Permission denied', Toast.LENGTH_SHORT).show();
                }
                return;
            }
        }
    }

    @Override
    public void onConnected(Bundle bundle) {
        mLocationRequest = new LocationRequest();
        mLocationRequest.setInterval(1000);
        mLocationRequest.setFastestInterval(1000);
        mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);

        if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
                == PackageManager.PERMISSION_GRANTED) {
            LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
        }
    }

    @Override
    public void onConnectionSuspended(int i) {
        Toast.makeText(this, 'Connection suspended', Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
        Toast.makeText(this, 'Connection failed', Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onLocationChanged(Location location) {
        mLastLocation = location;
        LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
        mTextView.setText('Lat: ' + location.getLatitude() + '\nLong: ' + location.getLongitude());
    }
}

This code sets up a GoogleApiClient to connect to the Google Location Services API, and requests permission to access the device's location. Once permission is granted, location updates are requested and the onLocationChanged method is called whenever the device's location changes. In this code, the location is displayed in a TextView. You could modify this code to check the user's location against bus schedules to determine when the next bus is coming.