Android – Location Update
Android – Location Update
Esta lição é baseada no exemplo Android Play Location que demonstra como usar a Fused Location Provider API para obter atualizações sobre a localização de um dispositivo. Ele fica localizada no Github no repositório do Google Samples (https://github.com/googlesamples/android-play-location/tree/master/LocationUpdates). Alguns pontos desse exemplo foram explicados com maiores detalhe a fim de facilitar o entedimento.
1- Crie um projeto Empty novo chamado ExemploLocationUpdate com uma classe chamada MainActivity.
2- Adicione as dependências abaixo
implementation 'com.android.support:design:28.0.0' implementation 'com.google.android.gms:play-services-location:16.0.0'
3- Adicione um RecyclerView ao arquivo de layout criado
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:baselineAligned="false"
android:orientation="horizontal">
<Button
android:id="@+id/start_updates_button"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="10dp"
android:layout_marginRight="10dp"
android:layout_weight="1"
android:gravity="center"
android:onClick="startUpdatesButtonHandler"
android:text="@string/start_updates" />
<Button
android:id="@+id/stop_updates_button"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginLeft="@dimen/small_margin"
android:layout_marginStart="@dimen/small_margin"
android:layout_weight="1"
android:enabled="false"
android:gravity="center"
android:onClick="stopUpdatesButtonHandler"
android:text="@string/stop_updates" />
</LinearLayout>
<TextView
android:id="@+id/latitude_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="@dimen/small_margin"
android:layout_marginStart="@dimen/small_margin"
android:textSize="@dimen/default_text_size" />
<TextView
android:id="@+id/longitude_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="@dimen/small_margin"
android:layout_marginStart="@dimen/small_margin"
android:textSize="@dimen/default_text_size" />
<TextView
android:id="@+id/last_update_time_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="@dimen/small_margin"
android:layout_marginStart="@dimen/small_margin"
android:textSize="@dimen/default_text_size" />
<TextView
android:id="@+id/location_inadequate_warning"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/location_settings_inadequate_warning"
android:visibility="invisible" />
</LinearLayout>
</android.support.constraint.ConstraintLayout>
No clique do botão START UPDATE o aplicativo começará a requisitar a localização atual e exibir as coordenadas abaixo. O botão STOP UPDATE interrompe o serviço.
4- Na classe MainActivity.java copie e cole o código abaixo.
Explicação 1: O método buildLocationSettingsRequest() cria um objeto LocationSettingsRequest que é usado para verificar se um dispositivo possui as configurações de localização necessárias.
Explicação 2: O método createLocationRequest() cria uma solicitação de localização. Os objetos LocationRequest são usados para solicitar uma qualidade de serviço para atualizações de local do FusedLocationProviderApi. As configurações ACCESS_COARSE_LOCATION e ACCESS_FINE_LOCATION controlam a precisão da localização atual. Quando a configuração ACCESS_FINE_LOCATION é especificada a API do provedor de local retorna as atualizações de local com precisão de alguns pés. A configuração ACCESS_COARSE_LOCATION retorna uma precisão equivalente a uma cidade.
Use o método setinterval () para especificar o intervalo no qual o local é calculado para seu aplicativo.
Use o setFastestInterval () para especificar o intervalo no qual o local computado para outros aplicativos é entregue ao seu aplicativo.
Use o método setPriority () para especificar a precisão da localização passando um dos seguintes valores como o argumento:
PRIORITY_HIGH_ACCURACY fornece a localização mais precisa possível
PRIORITY_BALANCED_POWER_ACCURACY fornece uma localização precisa enquanto otimiza o poder
O PRIORITY_LOW_POWER depende em grande parte das torres de celular e evita entradas GPS e Wi-Fi, fornecendo precisão aproximada (no nível da cidade) com consumo mínimo de bateria.
PRIORITY_NO_POWER recebe locais passivamente de outros aplicativos para os quais a localização já foi calculada.
Explicação 3: O método createLocationCallback() cria um objeto LocationCallback para receber eventos de retorno de chamadas de localização. Toda vez que uma localização for informada para a aplicação esse obejeto receberá a localização e irá guardar a localização em um objeto do tipo Location que representa a localização geográfica.
Explicação 4: o método startLocationUpdates() solicita atualizações de localização do FusedLocationApi. Um obejto FusedLocationProviderClient é criado e o método requestLocationUpdates() é responsável por fazer a solicitação de atualização de localização. Esse método não é chamado a menos que a permissão de tempo de execução da localização tenha sido concedida.
Explicação 5: o método startLocationUpdates() remove as solicitaçãoes de localização do FusedLocationApi. Um obejto FusedLocationProviderClient é criado e o método removeLocationUpdates() é responsável por remover as solicitação de atualização de localização.
Explicação 6: O método checkPermissions() verifica se tem permissão de acessar localização, o método requestPermissions() solicita a permissão caso não tenha e o método onRequestPermissionsResult() recebe a retorno da solicitação de permissão.
Explicação 7: o método updateLocationUI() atualiza as informações de localização na tela.
package com.example.totemarcal.exemplolocationupdate;
import android.Manifest;
import android.app.Activity;
import android.content.Intent;
import android.content.IntentSender;
import android.content.pm.PackageManager;
import android.location.Location;
import android.net.Uri;
import android.os.Bundle;
import android.os.Looper;
import android.provider.Settings;
import android.support.annotation.NonNull;
import android.support.design.widget.Snackbar;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.Toolbar;
import com.google.android.gms.common.api.ApiException;
import com.google.android.gms.common.api.ResolvableApiException;
import com.google.android.gms.location.FusedLocationProviderClient;
import com.google.android.gms.location.LocationCallback;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationResult;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.location.LocationSettingsRequest;
import com.google.android.gms.location.LocationSettingsResponse;
import com.google.android.gms.location.LocationSettingsStatusCodes;
import com.google.android.gms.location.SettingsClient;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
import java.text.DateFormat;
import java.util.Date;
import java.util.Locale;
/**
* Using location settings.
* <p/>
* Uses the {@link com.google.android.gms.location.SettingsApi} to ensure that the device's system
* settings are properly configured for the app's location needs. When making a request to
* Location services, the device's system settings may be in a state that prevents the app from
* obtaining the location data that it needs. For example, GPS or Wi-Fi scanning may be switched
* off. The {@code SettingsApi} makes it possible to determine if a device's system settings are
* adequate for the location request, and to optionally invoke a dialog that allows the user to
* enable the necessary settings.
* <p/>
* This sample allows the user to request location updates using the ACCESS_FINE_LOCATION setting
* (as specified in AndroidManifest.xml).
*/
public class MainActivity extends AppCompatActivity {
private static final String TAG = MainActivity.class.getSimpleName();
/**
* Code used in requesting runtime permissions.
*/
private static final int REQUEST_PERMISSIONS_REQUEST_CODE = 34;
/**
* Constant used in the location settings dialog.
*/
private static final int REQUEST_CHECK_SETTINGS = 0x1;
/**
* The desired interval for location updates. Inexact. Updates may be more or less frequent.
*/
private static final long UPDATE_INTERVAL_IN_MILLISECONDS = 10000;
/**
* The fastest rate for active location updates. Exact. Updates will never be more frequent
* than this value.
*/
private static final long FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS =
UPDATE_INTERVAL_IN_MILLISECONDS / 2;
// Keys for storing activity state in the Bundle.
private final static String KEY_REQUESTING_LOCATION_UPDATES = "requesting-location-updates";
private final static String KEY_LOCATION = "location";
private final static String KEY_LAST_UPDATED_TIME_STRING = "last-updated-time-string";
/**
* Provides access to the Fused Location Provider API.
*/
private FusedLocationProviderClient mFusedLocationClient;
/**
* Provides access to the Location Settings API.
*/
private SettingsClient mSettingsClient;
/**
* Stores parameters for requests to the FusedLocationProviderApi.
*/
private LocationRequest mLocationRequest;
/**
* Stores the types of location services the client is interested in using. Used for checking
* settings to determine if the device has optimal location settings.
*/
private LocationSettingsRequest mLocationSettingsRequest;
/**
* Callback for Location events.
*/
private LocationCallback mLocationCallback;
/**
* Represents a geographical location.
*/
private Location mCurrentLocation;
// UI Widgets.
private Button mStartUpdatesButton;
private Button mStopUpdatesButton;
private TextView mLastUpdateTimeTextView;
private TextView mLatitudeTextView;
private TextView mLongitudeTextView;
// Labels.
private String mLatitudeLabel;
private String mLongitudeLabel;
private String mLastUpdateTimeLabel;
/**
* Tracks the status of the location updates request. Value changes when the user presses the
* Start Updates and Stop Updates buttons.
*/
private Boolean mRequestingLocationUpdates;
/**
* Time when the location was updated represented as a String.
*/
private String mLastUpdateTime;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Locate the UI widgets.
mStartUpdatesButton = (Button) findViewById(R.id.start_updates_button);
mStopUpdatesButton = (Button) findViewById(R.id.stop_updates_button);
mLatitudeTextView = (TextView) findViewById(R.id.latitude_text);
mLongitudeTextView = (TextView) findViewById(R.id.longitude_text);
mLastUpdateTimeTextView = (TextView) findViewById(R.id.last_update_time_text);
// Set labels.
mLatitudeLabel = getResources().getString(R.string.latitude_label);
mLongitudeLabel = getResources().getString(R.string.longitude_label);
mLastUpdateTimeLabel = getResources().getString(R.string.last_update_time_label);
mRequestingLocationUpdates = false;
mLastUpdateTime = "";
// Update values using data stored in the Bundle.
updateValuesFromBundle(savedInstanceState);
mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this);
mSettingsClient = LocationServices.getSettingsClient(this);
// Kick off the process of building the LocationCallback, LocationRequest, and
// LocationSettingsRequest objects.
createLocationCallback();
createLocationRequest();
buildLocationSettingsRequest();
}
/**
* Updates fields based on data stored in the bundle.
*
* @param savedInstanceState The activity state saved in the Bundle.
*/
private void updateValuesFromBundle(Bundle savedInstanceState) {
if (savedInstanceState != null) {
// Update the value of mRequestingLocationUpdates from the Bundle, and make sure that
// the Start Updates and Stop Updates buttons are correctly enabled or disabled.
if (savedInstanceState.keySet().contains(KEY_REQUESTING_LOCATION_UPDATES)) {
mRequestingLocationUpdates = savedInstanceState.getBoolean(
KEY_REQUESTING_LOCATION_UPDATES);
}
// Update the value of mCurrentLocation from the Bundle and update the UI to show the
// correct latitude and longitude.
if (savedInstanceState.keySet().contains(KEY_LOCATION)) {
// Since KEY_LOCATION was found in the Bundle, we can be sure that mCurrentLocation
// is not null.
mCurrentLocation = savedInstanceState.getParcelable(KEY_LOCATION);
}
// Update the value of mLastUpdateTime from the Bundle and update the UI.
if (savedInstanceState.keySet().contains(KEY_LAST_UPDATED_TIME_STRING)) {
mLastUpdateTime = savedInstanceState.getString(KEY_LAST_UPDATED_TIME_STRING);
}
updateUI();
}
}
/**
* Sets up the location request. Android has two location request settings:
* {@code ACCESS_COARSE_LOCATION} and {@code ACCESS_FINE_LOCATION}. These settings control
* the accuracy of the current location. This sample uses ACCESS_FINE_LOCATION, as defined in
* the AndroidManifest.xml.
* <p/>
* When the ACCESS_FINE_LOCATION setting is specified, combined with a fast update
* interval (5 seconds), the Fused Location Provider API returns location updates that are
* accurate to within a few feet.
* <p/>
* These settings are appropriate for mapping applications that show real-time location
* updates.
*/
private void createLocationRequest() {
mLocationRequest = new LocationRequest();
// Sets the desired interval for active location updates. This interval is
// inexact. You may not receive updates at all if no location sources are available, or
// you may receive them slower than requested. You may also receive updates faster than
// requested if other applications are requesting location at a faster interval.
mLocationRequest.setInterval(UPDATE_INTERVAL_IN_MILLISECONDS);
// Sets the fastest rate for active location updates. This interval is exact, and your
// application will never receive updates faster than this value.
mLocationRequest.setFastestInterval(FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS);
mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
}
/**
* Creates a callback for receiving location events.
*/
private void createLocationCallback() {
mLocationCallback = new LocationCallback() {
@Override
public void onLocationResult(LocationResult locationResult) {
super.onLocationResult(locationResult);
mCurrentLocation = locationResult.getLastLocation();
mLastUpdateTime = DateFormat.getTimeInstance().format(new Date());
updateLocationUI();
}
};
}
/**
* Uses a {@link com.google.android.gms.location.LocationSettingsRequest.Builder} to build
* a {@link com.google.android.gms.location.LocationSettingsRequest} that is used for checking
* if a device has the needed location settings.
*/
private void buildLocationSettingsRequest() {
LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder();
builder.addLocationRequest(mLocationRequest);
mLocationSettingsRequest = builder.build();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode) {
// Check for the integer request code originally supplied to startResolutionForResult().
case REQUEST_CHECK_SETTINGS:
switch (resultCode) {
case Activity.RESULT_OK:
Log.i(TAG, "O usuário concordou em fazer as alterações nas configurações de localização necessárias.");
// Nothing to do. startLocationupdates() gets called in onResume again.
break;
case Activity.RESULT_CANCELED:
Log.i(TAG, "O usuário optou por não fazer as alterações necessárias nas configurações de localização.");
mRequestingLocationUpdates = false;
updateUI();
break;
}
break;
}
}
/**
* Handles the Start Updates button and requests start of location updates. Does nothing if
* updates have already been requested.
*/
public void startUpdatesButtonHandler(View view) {
if (!mRequestingLocationUpdates) {
mRequestingLocationUpdates = true;
setButtonsEnabledState();
startLocationUpdates();
}
}
/**
* Handles the Stop Updates button, and requests removal of location updates.
*/
public void stopUpdatesButtonHandler(View view) {
// It is a good practice to remove location requests when the activity is in a paused or
// stopped state. Doing so helps battery performance and is especially
// recommended in applications that request frequent location updates.
stopLocationUpdates();
}
/**
* Requests location updates from the FusedLocationApi. Note: we don't call this unless location
* runtime permission has been granted.
*/
private void startLocationUpdates() {
// Begin by checking if the device has the necessary location settings.
mSettingsClient.checkLocationSettings(mLocationSettingsRequest)
.addOnSuccessListener(this, new OnSuccessListener<LocationSettingsResponse>() {
@Override
public void onSuccess(LocationSettingsResponse locationSettingsResponse) {
Log.i(TAG, "All location settings are satisfied.");
//noinspection MissingPermission
if (ActivityCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getApplicationContext(), 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;
}
mFusedLocationClient.requestLocationUpdates(mLocationRequest,
mLocationCallback, null);
updateUI();
}
})
.addOnFailureListener(this, new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
int statusCode = ((ApiException) e).getStatusCode();
switch (statusCode) {
case LocationSettingsStatusCodes.RESOLUTION_REQUIRED:
Log.i(TAG, "As configurações de localização não estão satisfeitas. Tentando atualizar configurações de localização ");
try {
// Show the dialog by calling startResolutionForResult(), and check the
// result in onActivityResult().
ResolvableApiException rae = (ResolvableApiException) e;
rae.startResolutionForResult(MainActivity.this, REQUEST_CHECK_SETTINGS);
} catch (IntentSender.SendIntentException sie) {
Log.i(TAG, "PendingIntent unable to execute request.");
}
break;
case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:
String errorMessage = "As configurações de localização são inadequadas e não podem ser corrigidas aqui. Corrigir em configurações.";
Log.e(TAG, errorMessage);
Toast.makeText(MainActivity.this, errorMessage, Toast.LENGTH_LONG).show();
mRequestingLocationUpdates = false;
}
updateUI();
}
});
}
/**
* Updates all UI fields.
*/
private void updateUI() {
setButtonsEnabledState();
updateLocationUI();
}
/**
* Disables both buttons when functionality is disabled due to insuffucient location settings.
* Otherwise ensures that only one button is enabled at any time. The Start Updates button is
* enabled if the user is not requesting location updates. The Stop Updates button is enabled
* if the user is requesting location updates.
*/
private void setButtonsEnabledState() {
if (mRequestingLocationUpdates) {
mStartUpdatesButton.setEnabled(false);
mStopUpdatesButton.setEnabled(true);
} else {
mStartUpdatesButton.setEnabled(true);
mStopUpdatesButton.setEnabled(false);
}
}
/**
* Sets the value of the UI fields for the location latitude, longitude and last update time.
*/
private void updateLocationUI() {
if (mCurrentLocation != null) {
mLatitudeTextView.setText(String.format(Locale.ENGLISH, "%s: %f", mLatitudeLabel,
mCurrentLocation.getLatitude()));
mLongitudeTextView.setText(String.format(Locale.ENGLISH, "%s: %f", mLongitudeLabel,
mCurrentLocation.getLongitude()));
mLastUpdateTimeTextView.setText(String.format(Locale.ENGLISH, "%s: %s",
mLastUpdateTimeLabel, mLastUpdateTime));
}
}
/**
* Removes location updates from the FusedLocationApi.
*/
private void stopLocationUpdates() {
if (!mRequestingLocationUpdates) {
Log.d(TAG, "stopLocationUpdates: atualizações nunca solicitadas, no-op.");
return;
}
// It is a good practice to remove location requests when the activity is in a paused or
// stopped state. Doing so helps battery performance and is especially
// recommended in applications that request frequent location updates.
mFusedLocationClient.removeLocationUpdates(mLocationCallback)
.addOnCompleteListener(this, new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
mRequestingLocationUpdates = false;
setButtonsEnabledState();
}
});
}
@Override
public void onResume() {
super.onResume();
// Within {@code onPause()}, we remove location updates. Here, we resume receiving
// location updates if the user has requested them.
if (mRequestingLocationUpdates && checkPermissions()) {
startLocationUpdates();
} else if (!checkPermissions()) {
requestPermissions();
}
updateUI();
}
@Override
protected void onPause() {
super.onPause();
// Remove location updates to save battery.
stopLocationUpdates();
}
/**
* Stores activity data in the Bundle.
*/
public void onSaveInstanceState(Bundle savedInstanceState) {
savedInstanceState.putBoolean(KEY_REQUESTING_LOCATION_UPDATES, mRequestingLocationUpdates);
savedInstanceState.putParcelable(KEY_LOCATION, mCurrentLocation);
savedInstanceState.putString(KEY_LAST_UPDATED_TIME_STRING, mLastUpdateTime);
super.onSaveInstanceState(savedInstanceState);
}
/**
* Shows a {@link Snackbar}.
*
* @param mainTextStringId The id for the string resource for the Snackbar text.
* @param actionStringId The text of the action item.
* @param listener The listener associated with the Snackbar action.
*/
private void showSnackbar(final int mainTextStringId, final int actionStringId,
View.OnClickListener listener) {
Snackbar.make(
findViewById(android.R.id.content),
getString(mainTextStringId),
Snackbar.LENGTH_INDEFINITE)
.setAction(getString(actionStringId), listener).show();
}
/**
* Return the current state of the permissions needed.
*/
private boolean checkPermissions() {
int permissionState = ActivityCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION);
return permissionState == PackageManager.PERMISSION_GRANTED;
}
private void requestPermissions() {
boolean shouldProvideRationale =
ActivityCompat.shouldShowRequestPermissionRationale(this,
Manifest.permission.ACCESS_FINE_LOCATION);
// Provide an additional rationale to the user. This would happen if the user denied the
// request previously, but didn't check the "Don't ask again" checkbox.
if (shouldProvideRationale) {
Log.i(TAG, "Exibindo justificativa de permissão para fornecer contexto adicional.");
showSnackbar(R.string.permission_rationale,
android.R.string.ok, new View.OnClickListener() {
@Override
public void onClick(View view) {
// Request permission
ActivityCompat.requestPermissions(MainActivity.this,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
REQUEST_PERMISSIONS_REQUEST_CODE);
}
});
} else {
Log.i(TAG, "Requesting permission");
// Request permission. It's possible this can be auto answered if device policy
// sets the permission in a given state or the user denied the permission
// previously and checked "Never ask again".
ActivityCompat.requestPermissions(MainActivity.this,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
REQUEST_PERMISSIONS_REQUEST_CODE);
}
}
/**
* Callback received when a permissions request has been completed.
*/
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
@NonNull int[] grantResults) {
Log.i(TAG, "onRequestPermissionResult");
if (requestCode == REQUEST_PERMISSIONS_REQUEST_CODE) {
if (grantResults.length <= 0) {
// If user interaction was interrupted, the permission request is cancelled and you
// receive empty arrays.
Log.i(TAG, "User interaction was cancelled.");
} else if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
if (mRequestingLocationUpdates) {
Log.i(TAG, "Permission granted, updates requested, starting location updates");
startLocationUpdates();
}
} else {
// Permission denied.
// Notify the user via a SnackBar that they have rejected a core permission for the
// app, which makes the Activity useless. In a real app, core permissions would
// typically be best requested during a welcome-screen flow.
// Additionally, it is important to remember that a permission might have been
// rejected without asking the user for permission (device policy or "Never ask
// again" prompts). Therefore, a user interface affordance is typically implemented
// when permissions are denied. Otherwise, your app could appear unresponsive to
// touches or interactions which have required permissions.
showSnackbar(R.string.permission_denied_explanation,
R.string.settings, new View.OnClickListener() {
@Override
public void onClick(View view) {
// Build intent that displays the App settings screen.
Intent intent = new Intent();
intent.setAction(
Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
Uri uri = Uri.fromParts("package",
BuildConfig.APPLICATION_ID, null);
intent.setData(uri);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
}
});
}
}
}
}
5- Adicione ao projeto os arquivo style.xml, string.xml, colors.xml e dimens.xml.
- Android Toast e AlertDialog
- Android ListActivity – (Parte 1 – ListActivity)
- Android – RecyclerView
- Android Layouts (ViewGroups) – (Parte 2 – RalativeLayout )
- Android SharedPreferences