Android - startActivityForResult 立即触发 onActivityResult

Question

I am launching activities from the main activity in my app using the call startActivityForResult(intent, ACTIVITY_TYPE) , and they are all working but one.

This one, when called, launches the activity as desired, but in the log I can see that onActivityResult() is immediately being triggered. The activity shows up but RESULT_CANCELED is immediately returned to onActivityResult() .

I then interact with the activity, press a button which calls finish() , and onActivityResult() is not called this time (because apparently a result has already been returned).

Does this make sense to anyone? Has anyone seen this behavior before?

Answer 1

You can't use startActivityForResult() if your activity is being launched as a singleInstance or singleTask . standard or singleTop launch mode will fix the problem.

Answer 2

Additionally make sure the intent does not have the Intent.FLAG_ACTIVITY_NEW_TASK set.

From the docs :

This flag can not be used when the caller is requesting a result from the activity being launched.

Answer 3

I have seen this behavior before, please make sure your destnation activity (that special activity) is not singleInstance in AndroidManifest file. If the Activity is singleInstance , then it will return RESULT_CANCELED before launched!

Answer 4

I'd also like to add that you could call an external app with:
Intent in = caller.getPackageManager().getLaunchIntentForPackage("com.your.package.here");
Which would create an intent with Intent.FLAG_ACTIVITY_NEW_TASK added by default, so call:
in.setFlags(0);
Which will clear that flag, and then you can proceed to: startActivityForResult(in, action);

Reason I'm doing this is that I have a utility app that has common functionality between a few other apps and I can keep the code changes to one location instead of worrying about multiple updates.

Answer 5

startActivityForResult() doesn't work with a singleInstance or singleTask activity in pre-lollipop version of Android. Since Android 5 it works (see this answer for more details).

Answer 6

It also triggers if you have FLAG_ACTIVITY_NEW_TASK in your intent.

Intent intent = new Intent(this, MyActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivityForResult(intent, REQUEST_CODE);

Answer 7

My problem was with the calling activity. Its declaration in the AndroidManifest had the following property:

android:noHistory="true"

Changed it to "false" and now works fine.

Answer 8

Android 4.4 has a small problem about waiting for the return at the end of the actvity closure To solve this behavior it is important to set :

• all activities will have the same task Affinity attribute. ( TaskAffinity = "[SAME STRING]" )
• launchmode=singleTop,
• launchIntent.SetFlags(0); // for reset default Intent flags if you launch from package manager

This solution works with all version of Android

See this for taskAffinity: https://asyoulook.com/computers%20&%20internet/android-onactivityresult-being-called-instantly/1004072

Answer 9

另外，检查清单中的活动是否 android:noHistory="true" ，如果是，它将不起作用。

Answer 10

For ActivityGroup or TabHost and others, maybe the xxxActivity is a subActivity of its parent. Then the startActivityForResult can not work but the parent can get the result.

1. call getParent().startActivityForResult() from your sub-activity

2. your parent (the ActivityGroup ) will be able to handle the onActivityResult . So I created a subclass of ActivityGroup and handled this onActivityResult .

3. You can re-route that result back to the sub-activity if you need to. Just get the current activity by getLocalActivityManager().getCurrentActivity() . My sub-activities inherit from a custom activity so I added a handleActivityResult(requestCode, resultCode, data) in that subclass for the ActivityGroup to call.

example: http://www.cnblogs.com/relinson/archive/2012/03/25/startActivityForResult.html

Answer 11

如果您在清单文件中拼错了包或类名， onActivityResult()也会将RESULT_CANCELED作为resultCode传递。

Answer 12

在 Android Manifest 中，为您想要打开的活动设置android:launchMode="singleTop"并在打开活动时设置标志intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);

Answer 13

如果您在 AndroidManifest.xml 的 Activity 中定义了android:noHistory="true" ，则会在此处导致相同的问题。