android - Why does starting an activity from a widget cause my main activity to start as well?

Question

When I start an activitiy from a widget I want the back button to go to the home screen but instead it goes to the app's main activity. After toying around I found that if I somehow close the main app activity, this problem doesn't occur. Strange.

I found a solution here that said to call finish(); in my main activity's onPause(). Obviously this is the wrong solution e.g. reorientation of the screen causes an onPause() so the will activity will die whenever the phone is rotated.

This is how I start my activity:

@Override
public void onReceive(Context context, Intent intent) {
    [...]
        //new Emergency().emDialog(context).show();
        Intent myIntent = new Intent(context, EmergencyActivity.class);

        // FLAG_ACTIVITY_NEW_TASK is needed because we're not in an activity
        // already, without it we crash.
        myIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(myIntent);

You can see the rest of the code at http://code.google.com/p/emergencybutton/source/browse

edit: I tried running the activity differently, but still it doesn't work correctly:

Intent myIntent = new Intent();
myIntent.setClassName("com.emergency.button", "com.emergency.button.EmergencyActivity");

Answer 1

Ok, so I'm not exactly sure what happened here but android:launchMode="singleInstance" in the activity in AndroidManifest.xml fixed it somehow.

    <activity android:name=".EmergencyActivity"
              android:launchMode="singleInstance"

@Octavian - I should have clarified that I start the activity from an onReceive in an AppWidgetProvider. I'm at the home screen, starting an activity titled B, but somehow both A and B are in the activity stack instead of just B.

http://developer.android.com/guide/topics/manifest/activity-element.html#lmode