Develop Reference

Why must you use Intent.setAction and Intent.AddCategory to use singleTop with PendingIntent?

I'm using example code to create a notification, which I then want to handle in onNewIntent() if my App is already running. However, onNewIntent() was not being called. I searched for a few hours and no one seemed to have a proper answer--just some workarounds.
I had to search forever to find the solution here: Android OnNewIntent not called and the answer is not actually explained.
Question
Can anyone explain why we need the lines:
resultIntent.setAction(Intent.ACTION_MAIN);
resultIntent.addCategory(Intent.CATEGORY_LAUNCHER);
in order to receive the notification through onNewIntent()? The App launches just fine without them, but will always go through onCreate() instead.
Example Code
public void createNotification(String s){
// The id of the channel.
String CHANNEL_ID = "my_channel_01";
NotificationCompat.Builder mBuilder =
(NotificationCompat.Builder) new NotificationCompat.Builder(this)
.setSmallIcon(R.drawable.icon_missing)
.setContentTitle(getString(R.string.notification_channel_name))
.setContentText(R.string.text);
// Creates an explicit intent for an Activity in your app
Intent resultIntent = new Intent(this, MainActivity.class);
resultIntent.setAction(Intent.ACTION_MAIN);
resultIntent.addCategory(Intent.CATEGORY_LAUNCHER);
// The stack builder object will contain an artificial back stack for the
// started Activity.
// This ensures that navigating backward from the Activity leads out of
// your app to the Home screen.
TaskStackBuilder stackBuilder = TaskStackBuilder.create(this);
// Adds the back stack for the Intent (but not the Intent itself)
stackBuilder.addParentStack(MainActivity.class);
// Adds the Intent that starts the Activity to the top of the stack
stackBuilder.addNextIntent(resultIntent);
PendingIntent resultPendingIntent =
stackBuilder.getPendingIntent(
0,
PendingIntent.FLAG_UPDATE_CURRENT
);
mBuilder.setContentIntent(resultPendingIntent);
NotificationManager mNotificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// mNotificationId is a unique integer your app uses to identify the
// notification. For example, to cancel the notification, you can pass its ID
// number to NotificationManager.cancel().
Notification n = mBuilder.build();
n.flags = n.flags | Notification.FLAG_AUTO_CANCEL;
mNotificationManager.notify(1, n);
}

Execute a method from notification

I have an application,I am sending notification with this code
private void notBuild() {
int mId=1;
NotificationCompat.Builder mBuilder =
new NotificationCompat.Builder(this)
.setContentTitle("Message")
.setAutoCancel(true)
.setSmallIcon(R.drawable.twitter)
.setContentText("user01 sent a message")
.setNumber(15);
// Creates an explicit intent for an Activity in your app
Intent resultIntent = new Intent(this, MainActivity.class);
// The stack builder object will contain an artificial back stack for the
// started Activity.
// This ensures that navigating backward from the Activity leads out of
// your application to the Home screen.
TaskStackBuilder stackBuilder = TaskStackBuilder.create(this);
// Adds the back stack for the Intent (but not the Intent itself)
stackBuilder.addParentStack(MainActivity.class);
// Adds the Intent that starts the Activity to the top of the stack
stackBuilder.addNextIntent(resultIntent);
PendingIntent resultPendingIntent =
stackBuilder.getPendingIntent(
0,
PendingIntent.FLAG_UPDATE_CURRENT
);
mBuilder.setContentIntent(resultPendingIntent);
NotificationManager mNotificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// mId allows you to update the notification later on.
mNotificationManager.notify(mId, mBuilder.build());
}
This is starting mainactivity and it's okay.But I want to run a method in the main activity.
Example:You will see in the setContentText user01 sent a message,when user press the notification I want to run startChat(user01) method in the main activity.How can I do it ?

You can put data in the resultIntent variable.
resultIntent.putExtra('key', 'useridhere');
Then, in your Activity (onCreate or OnResume) you can call
String userId = getIntent().getStringExtra('key', null);
if(userId != null)
{
//StartChat(....);
}

keep posting the same notification

I am trying to post a notification on a button press using this code:
public void onClick(View v) {
NotificationCompat.Builder mBuilder =
new NotificationCompat.Builder(this)
.setSmallIcon(R.drawable.ic_launcher)
.setContentTitle("My notification")
.setContentText("Hello World!");
// Creates an explicit intent for an Activity in your app
Intent resultIntent = new Intent(this, MainActivity.class);
// The stack builder object will contain an artificial back stack for the
// started Activity.
// This ensures that navigating backward from the Activity leads out of
// your application to the Home screen.
TaskStackBuilder stackBuilder = TaskStackBuilder.create(this);
// Adds the back stack for the Intent (but not the Intent itself)
stackBuilder.addParentStack(MainActivity.class);
// Adds the Intent that starts the Activity to the top of the stack
stackBuilder.addNextIntent(resultIntent);
PendingIntent resultPendingIntent =
stackBuilder.getPendingIntent(
0,
PendingIntent.FLAG_UPDATE_CURRENT
);
mBuilder.setContentIntent(resultPendingIntent);
NotificationManager mNotificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// mId allows you to update the notification later on.
i = (int) Math.random();
mNotificationManager.notify(i, mBuilder.build());
}
and I know the .notfiy(id, notification) allow it to only post one notification with the same ID but just for the sake of this example app i would like to keep being able to post notifications even it it is the same one. Thats why i tried to use a random number so it would switch the id, but that still didnt help. Any suggestions?
by the way this is posting a notification, but only one until i clear it

Use a global int 'i=0' and increment it after every notification creation and change code like following
public void onClick(View v) {
NotificationCompat.Builder mBuilder =
new NotificationCompat.Builder(this)
.setSmallIcon(R.drawable.ic_launcher)
.setContentTitle("My notification")
.setContentText("Hello World!");
// Creates an explicit intent for an Activity in your app
Intent resultIntent = new Intent(this, MainActivity.class);
// The stack builder object will contain an artificial back stack for the
// started Activity.
// This ensures that navigating backward from the Activity leads out of
// your application to the Home screen.
TaskStackBuilder stackBuilder = TaskStackBuilder.create(this);
// Adds the back stack for the Intent (but not the Intent itself)
stackBuilder.addParentStack(MainActivity.class);
// Adds the Intent that starts the Activity to the top of the stack
stackBuilder.addNextIntent(resultIntent);
i++;
PendingIntent resultPendingIntent =
stackBuilder.getPendingIntent(
i,
PendingIntent.FLAG_UPDATE_CURRENT
);
mBuilder.setContentIntent(resultPendingIntent);
NotificationManager mNotificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// mId allows you to update the notification later on.
mNotificationManager.notify(i, mBuilder.build());
}
Hope this will resolve the issue

Launching an activity of the application on clicking the notification

I like to launch one of my activities in my application on clicking the notification.
I designed a pending intent as discussed in the link Notifications.
But when i click the notification, an activity is launched but that is not the activity supposed to launch from my application. Just the activity that has same class name as my activity is launched. I set a break point in my activity and the break point is never hit.
What is wrong? NotificationListActivity is the one I like to launch. Now the activity titled with NotificationListActivity is launched, but not my activity.
Intent resultIntent = new Intent(thisclasscontext, NotificationListActivity.class);
resultIntent.putExtra("MOBILENUMBER", tel);
TaskStackBuilder stackBuilder = TaskStackBuilder.create(thisclasscontext);
// Adds the back stack for the Intent (but not the Intent itself)
stackBuilder.addParentStack(NotificationListActivity.class);
// Adds the Intent that starts the Activity to the top of the stack
stackBuilder.addNextIntent(resultIntent);
PendingIntent resultPendingIntent = stackBuilder.getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);
mBuilder.setContentIntent(resultPendingIntent);

You can use the below as a reference it works
public void notification()
{
int mId=1;
NotificationCompat.Builder mBuilder =
new NotificationCompat.Builder(this)
.setSmallIcon(R.drawable.ic_launcher)
.setContentTitle("My notification")
.setContentText("Hello World!");
// Creates an explicit intent for an Activity in your app
Intent resultIntent = new Intent(MainActivity.this, SecondActivity.class);
// The stack builder object will contain an artificial back stack for the
// started Activity.
// This ensures that navigating backward from the Activity leads out of
// your application to the Home screen.
TaskStackBuilder stackBuilder = TaskStackBuilder.create(MainActivity.this);
// Adds the back stack for the Intent (but not the Intent itself)
stackBuilder.addParentStack(SecondActivity.class);
// Adds the Intent that starts the Activity to the top of the stack
stackBuilder.addNextIntent(resultIntent);
PendingIntent resultPendingIntent =
stackBuilder.getPendingIntent(
0,
PendingIntent.FLAG_UPDATE_CURRENT
);
mBuilder.setContentIntent(resultPendingIntent);
NotificationManager mNotificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// mId allows you to update the notification later on.
mNotificationManager.notify(mId, mBuilder.build());
}

How to launch activity from click on notification?

How do I launch an activity when the user clicks on the notification? I am having constant crashes. I can not get the click on the notification to work. There is an onclick method shown below. When a button called ButtonOne is pressed, it will launch a notification in the top menu bar of the screen. I wanted to user to be able to press the notification and have it launch the activity called MainActivity. It crashes and will not launch the page. There is probably something wrong in my code for notification that I put inside of the MainActivity class. What is wrong?
ButtonOne.setOnClickListener(new View.OnClickListener() {
private int mId;
// anonymous inner class override for on click
public void onClick(View v) {
Intent myIntent = new Intent(MainActivity.this, CoverFlowExample.class);
MainActivity.this.startActivity(myIntent);
NotificationCompat.Builder mBuilder =
new NotificationCompat.Builder(MainActivity.this)
.setSmallIcon(R.drawable.ic_launcher)
.setContentTitle("My notification")
.setContentText("Hello World!");
// Creates an explicit intent for an Activity in your app
Intent resultIntent = new Intent(MainActivity.this, MainActivity.class);
// The stack builder object will contain an artificial back stack for the
// started Activity.
// This ensures that navigating backward from the Activity leads out of
// your application to the Home screen.
TaskStackBuilder stackBuilder = TaskStackBuilder.create(MainActivity.this);
// Adds the back stack for the Intent (but not the Intent itself)
stackBuilder.addParentStack(MainActivity.class);
// Adds the Intent that starts the Activity to the top of the stack
stackBuilder.addNextIntent(resultIntent);
PendingIntent resultPendingIntent =
stackBuilder.getPendingIntent(
0,
PendingIntent.FLAG_UPDATE_CURRENT
);
mBuilder.setContentIntent(resultPendingIntent);
NotificationManager mNotificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// mId allows you to update the notification later on.
mNotificationManager.notify(mId, mBuilder.build());
}
});

Found out that the problem was the AVD android emulator not the code. For some reason it did not update the code from earlier version. Tested it again and now it runs with no errors.