Android Notifications

In this tutorial we shall learn about different types of notifications in android. Following are the three types of android notifications,

1. Toast Notification – Shows message that fades away after a few seconds. (Background type also)
2. Status Notification – Shows notification message and displayed till user action. (Background type also)
3. Dialog Notification – Comes out of an active Activity.

(Background type) – is result of some background Service event that may not be related to current activity. That is, we can use this notification type in Service also, added to Activity.

1. Toast Notification

This type of notification will be used when there is no need of user interaction on seeing this message. This message occupies a rectangular box which will fade in and fade out after some time. The size of the box depends on the message content.

For example, when user creates an event using calendar application it will notify the user as “Event Created” after the create action is completed. Refer the image.

Toast notification is best suited for one way information to the use where we don’t expect any response. Toast message does not stop or disturb the current activity, just the message is shown in parallel.

Example for Android Toast Notification

Toast notification can be created from an Activity or Service. Toast is the class to be used as below,

Context appContext = getApplicationContext();
Toast mailMessage = Toast.makeText(appContext, “Email Received.”, Toast. LENGTH_LONG);
mailMessage.setGravity(Gravity.TOP, 0, 0); //optional
mailMessage.show();

• duration – can be either LENGTH_SHORT or LENGTH_LONG
• setGravity – is used to position the message in screen. By default it shows at bottom centered. First parameter is Gravity a constant identifying location in container broadly like TOP | BOTTOM | LEFT … , second and third parameters are x, y-offset.

2. Status Notification

Status notification is used to display rich notification information especially from a (background) Service where user can interact. It will be shown as an icon with an alert in the status bar. When the user pulls down the status bar, the list of notification will be in the notification window.

For example when a SMS message is received a message icon is shown in the status bar. On pull down, the list of unread messages will be shown in the notification window.

Example shown in image: On snoozing the alarm, corresponding notification will be will be sent to the status bar with notification icon. A ticker message will be shown next to the icon for some time. In the image the clock icon represents the notification about the snooze event and the ticker message is shown next to the clock icon.

1. Create a simple notification with an icon alert. Alert can be a ticker text message or sound or vibration or flashlight.
2. Associate notification message with details shown on message expansion to activity/intent. Notification message can be a list and it is identified using a unique identifier. Existing messages can be updated too.
3. Register the notification message with notification manager. NotificationManager is a system service that manages all the notifications.

Example for Android Status Notification

//part 1 – notification icon alert
int icon = R.drawable.notification_icon;
// a ticker text message or sound or vibration or flashlight can be used for alert
CharSequence ticker = “Hi”;
long showAt = System.currenttimeMillis(); //immediately
Notification notification = new Notification(icon, ticker, showAt);
//part 2 – associate notification message with details shown on message expansion to activity/intent
CharSequence notificationTitle = "Notification:";
CharSequence notificationMessage = "SMS Received.";
Intent intent = new Intent(this, Activity.class);
PendingIntent objPendingIntent = PendingIntent.getActivity(this, 0, intent, 0);
Context ctx = getApplicationContext();
notification.setLatestEventInfo(ctx, notificationTitle, notificationMessage, objPendingIntent);
//part 3 – register the notification message with notification manager
private static final int notificationIdentifier = 101; //an unique number set by developer to identify a notification, using this notification can be updated/replaced
NotificationManager notificationManager = (NotificationManager)
getSystemService(Context.NOTIFICATION_SERVICE);
notificationManager.notify(notificationIdentifier, objNotification);

Notification Alerts

Sound:

notification.defaults |= Notification.DEFAULT_SOUND;
//use the above default or set custom valuse as below
notification.sound = Uri.parse("file:///sdcard/notification/robo_da.mp3");

Vibration:

notification.defaults |= Notification.DEFAULT_VIBRATE;
//use the above default or set custom valuse as below
long[] vibrate = {0,200,100,200};
notification.vibrate = vibrate;

Flash Light:

notification.defaults |= Notification.DEFAULT_LIGHTS;
//use the above default or set custom valuse as below
notification.ledARGB = 0xffff0000;//red color
notification.ledOnMS = 400;
notification.ledOffMS = 500;
notification.flags |= Notification.FLAG_SHOW_LIGHTS;

3. Dialog Notification

Dialog notification is not an exact type of notification. Dialog is common in window based UIs. A small panel that appears on top of an active window and user will not be able to do any other activity other than acting on the dialog. This is same here too. From an android Activity a dialog will be launched and the Activity loses focus. User should give input and work on the dialog. Once the user action is completed the dialog is closed. Dialog has many uses and one among them is notification to user.

For example we can show a progress bar which is a notification to user. We can ask for confirmation ‘yes’ or ‘no’ from user and this is a type of notification. For all these purposes dialog notification is used. There are many types of dialogs available such as,

• AlertDialog
• ProgressDialog
• DatePickerDialog
• TimePickerDialog

Soon, I will write a separate detailed tutorial for Android dialogs.