Android - When launch the same activity from widge

问题:

I have a widget that contains 4 buttons to show 4 stock prices, each of them will launch into the same activity Quote.class to show stock details. In onUpdate(), it will set up the pendingIntent with extras with stock symbol. After I hit button A, it goes to Quote activity that shows stock A. Then I hit the BACK button to the homescreen, Quote activity calls onDestroy() and when I hit button B, stock B will show properly. However, when i hit HOME button after it shows stock A, the Quote activity only calls onStop without calling onDestroy(), then as i hit button B, it will call onStart() and it shows the same instance that shows stock A.

RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.etappwidget); 
setQuoteIntent(context, views, R.id.view1, "BAC", 1);
setQuoteIntent(context, views, R.id.view2, "C", 2);
setQuoteIntent(context, views, R.id.view3, "GOOG", 3);
setQuoteIntent(context, views, R.id.view4, "AAPL", 4);

 private static void setQuoteIntent(Context context, RemoteViews views, int viewId, String symbol, int requestCode) {
 Intent i = new Intent(context, Quote.class);
 i.putExtra("SYMBOL", symbol);
 i.setFlags(Intent.FLAG_ACTIVITY_MULTIPLE_TASK);
 PendingIntent pi = PendingIntent.getActivity(context, requestCode, i, PendingIntent.FLAG_UPDATE_CURRENT);
 views.setOnClickPendingIntent(viewId, pi);

}

Originally I thought adding a flag in the Intent should solve this problem. But I have tried i.setFlags(Intent.FLAG_ACTIVITY_MULTIPLE_TASK or FLAG_ACTIVITY_NEW_TASK or FLAG_ACTIVITY_NO_HISTORY), none of them makes any difference.

So is there any ways to make it work? How can i remove the history stack from HOME button? How can I call onCreate in Quote activity and get new extras when i hit button B? Any help is appreciated. Thanks

回答1:

• It is normal for onDestroy to possibly not get called if you do simple task switching (like holding the HOME button). If you need to do clean-up, it needs to go in onPause.
• I believe the problem is that you have a PendingIntent that only differs by extra. PendingIntents are cached, so if you use two with the same action and data, they'll overwrite each other. You can circumvent that by giving each some random data. Try passing the symbol in the data rather than through the extra (which is preferred anyway).

回答2:

You can try this:

        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setFlags(Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS);

Your activity will not be seen in the history stack

回答3:

clickIntent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);

Since: API Level 1 If set, the new activity is not kept in the history stack. As soon as the user navigates away from it, the activity is finished. This may also be set with the noHistory attribute.

This solved the same issue of mine while implementing widget activities.

回答4:

When you press home, most probably the activity will not be destroyed. It is put to pause state in such case. So, I guess your code to initiate the stock view would stationed in onCreate rather than onResume. So, moving those to onResume should solve the problem.

回答5:

If you are using a different Action in your Intent and use the SingleTop or similar flag and override onNewIntent to detect the correct action that should do the trick. You need to be prepared to handle the intent in onCreate and onNewIntent.