Learn Android
AlarmManager
Many a times we want some task to be performed at some later time in future.For Example: In SMS Scheduler we want a SMS to be send at some later time, or Task Reminder in which we want to be reminded about a task at a particular time, to implement all these things we use AlramManager class.
AlarmManager class provides access to the system alarm services. These allow you
to schedule your application to be run at some point in the future. When
an alarm goes off, the
Intent that had been registered for it
is broadcast by the system, automatically starting the target application
if it is not already running. Registered alarms are retained while the
device is asleep (and can optionally wake the device up if they go off
during that time), but will be cleared if it is turned off and rebooted. Context.startService(), it
is possible that the phone will sleep before the requested service is launched.
To prevent this, your BroadcastReceiver and Service will need to implement a
separate wake lock policy to ensure that the phone continues running until the
service becomes available.AlarmManager Example
In the example I will schedule an alarm to send SMS at a particular time in future.We have two classes
1: MainAcitvity: in this class, we will schedule the alarm to be triggered at particular time .
2: AlarmReciever: when the alarm triggers at scheduled time , this class will receive the alarm, and send the SMS.
AlarmReciever class extends BroadcastReceiver and overrides onRecieve() method.
Permission Required
we need <uses-permission android:name="com.android.alarm.permission.SET_ALARM"/> permission to use the AlarmManger in our application, so do not forget to declare the permission in manifest file
AndroidManifest file
<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.learnandroideasily.blogspot"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="8"
android:targetSdkVersion="17" />
<!-- permission required to use Alarm Manager -->
<uses-permission android:name="com.android.alarm.permission.SET_ALARM"/>
<!-- permission required to Send SMS -->
<uses-permission android:name="android.permission.SEND_SMS"/>
<application
android:icon="@drawable/ic_launcher"
android:label="Demo App" >
<activity
android:name=".MainActivity"
android:label="Demo App" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<!-- Register the Alarm Receiver -->
<receiver android:name=".AlarmReciever"/>
</application>
</manifest>
main.xml
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:gravity="center_vertical"
xmlns:android="http://schemas.android.com/apk/res/android">
<TextView
android:id="@+id/textView1"
android:gravity="center_horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Alarm Manager Example"
android:textAppearance="?android:attr/textAppearanceLarge" />
<Button
android:id="@+id/button1"
android:layout_marginTop="25dp"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Schedule The Alarm"
android:onClick="scheduleAlarm"/>
</LinearLayout>
MainActivity.java
public class MainActivity extends Activity
{
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
public void scheduleAlarm(View V)
{
// time at which alarm will be scheduled here alarm is scheduled at 1 day from current time,
// we fetch the current time in milliseconds and added 1 day time
// i.e. 24*60*60*1000= 86,400,000 milliseconds in a day
Long time = new GregorianCalendar().getTimeInMillis()+24*60*60*1000;
// create an Intent and set the class which will execute when Alarm triggers, here we have
// given AlarmReciever in the Intent, the onRecieve() method of this class will execute when
// alarm triggers and
//we will write the code to send SMS inside onRecieve() method pf Alarmreciever class
Intent intentAlarm = new Intent(this, AlarmReciever.class);
// create the AlarmManager object
AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
//set the alarm for particular time
alarmManager.set(AlarmManager.RTC_WAKEUP,time, PendingIntent.getBroadcast(this,1, intentAlarm, PendingIntent.FLAG_UPDATE_CURRENT));
Toast.makeText(this, "Alarm Scheduled for Tommrrow", Toast.LENGTH_LONG).show();
}
}
AlarmReciever.java
public class AlarmReciever extends BroadcastReceiver
{
@Override
public void onReceive(Context context, Intent intent)
{
// TODO Auto-generated method stub
String phoneNumberReciver="9718202185";// phone number to which SMS to be send
String message="Hi I will be there later, See You soon";// message to send
SmsManager sms = SmsManager.getDefault();
sms.sendTextMessage(phoneNumberReciver, null, message, null, null);
// Show the toast like in above screen shot
Toast.makeText(context, "Alarm Triggered and SMS Sent", Toast.LENGTH_LONG).show();
}
}
Advance Android Topics
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Showing Toast for Longer Time
Customizing the Display Time of Toast
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More Android Topics:
Android : Introduction
Eclipse Setup for Android Development
Configuring Eclipse for Android DevelopmentBegging With Android
Creating Your First Android ProjectUnderstanding Android Manifest File of your android app
Working With Layouts
Understanding Layouts in AndroidWorking with Linear Layout (With Example)
Nested Linear Layout (With Example)
Table Layout
Frame Layout(With Example)
Absolute Layout
Grid Layout
Activity
Activity In AndroidActivity Life Cycle
Starting Activity For Result
Sending Data from One Activity to Other in Android
Returning Result from Activity
Working With Views
Using Buttons and EditText in AndroidUsing CheckBoxes in Android
Using AutoCompleteTextView in Android
Grid View
Toast
Customizing Toast In AndroidCustomizing the Display Time of Toast
Customizing Toast At Runtime
Adding Image in Toast
Showing Toast for Longer Time
Dialogs In Android
Working With Alert DialogAdding Radio Buttons In Dialog
Adding Check Boxes In Dialog
Creating Customized Dialogs in Android
Adding EditText in Dialog
Creating Dialog To Collect User Input
DatePicker and TimePickerDialog
Using TimePickerDialog and DatePickerDialog In androidWorking With SMS
How to Send SMS in AndroidHow To Receive SMS
Accessing Inbox In Android
ListView:
Populating ListView With DataBaseMenus In Android
Creating Option MenuCreating Context Menu In Android
TelephonyManager
Using Telephony Manager In AndroidWorking With Incoming Calls
How To Handle Incoming Calls in AndroidHow to Forward an Incoming Call In Android
CALL States In Android
Miscellaneous
Notifications In AndroidHow To Vibrate The Android Phone
Sending Email In Android
Opening a webpage In Browser
How to Access PhoneBook In Android
Prompt User Input with an AlertDialog
Storage: Storing Data In Android
Shared Prefferences In Android
SharedPreferences In AndroidFiles: File Handling In Android
Reading and Writing files to Internal StoarageReading and Writing files to SD Card
DataBase : Working With Database
Working With Database in AndroidCreating Table In Android
Inserting, Deleting and Updating Records In Table in Android
How to Create DataBase in Android
Accessing Inbox In Android
