Question

I have a broadcast receiver which will launch an Activity onReceive.

When launched, this activity will perform a long task and call finish() at the end.

I do not want to trigger another launch of Activity when the previous Activity is still performing the long task. How can I launch only a singletask activity? I have set this in the manifest.

android:launchMode="singleTask"

In my onReceive method,

public void onReceive(Context context, Intent intent) {
    Intent activity = new Intent(context, Preview.class);
    activity.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    context.startActivity(activity);
}

Don’t seems to work.

The Activity class actually is a MediaRecorder which will record a video clip (say 10 sec). Thus I do not want to trigger another Activity while this recording is still incomplete.

Answer 1

You just need to have some way for your activity to communicate to your receiver to let it know whether or not it is already running. If you have that then you can make an if statement in the receiver that will keep it from launching multiples.

One option is a static boolean in your activity that indicates whether or not you are currently running. Then you can check that boolean from the receiver, and if it is true, then don’t call startActivity().

your activity would need something like this:

public YourActivity extends Activity{
    public static isRunning = false;
    public void onStart(){
        ...
        isRunning = true;
    }
    public void onStop(){
    ...
        isRunning = false;
    }
}

now in your receiver you can make a simple if statement that will check the value of isRunning:

public void onReceive(Context context, Intent intent) {
    if(YourActivity.isRunning == false){
        Intent activity = new Intent(context, Preview.class);
        activity.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(activity);
    }
}