I have two Activity: Activity1 and Activity2
Activity1 start Activity2 and I want to send a result from Activity2 to Activity1, but I can't use startActivityForResult() cause the lanuchmode of Activity1 is singelInstance. Are there any ways to send a callback from Activity1 to Activity2?(So far as I konw, one is send BroadCaseReceiver, the other is made a static param in Activity2)
Many thanks!
startActivityForResult not working properly with launchMode singleInstance
A similar question, it suggested using saved instance state and or saving information to a db/global storage.
onActivityResult do not fire if launch mode of activity is singleInstance
Proposes that you use a different type, replacing singleInstance with singleTask
You could extend the activity you want to launch and force its type to a different one for this scenario, leaving the original as SingleInstance.
It will not work to use broadcast to communicate between two Activities. Only one of the Activities will ever be active at a time. It does make sense to use it to communicate between an Activity and a Service, for example.
Generally you can use intent extras to pass information to the next Activity. I.e, using putExtra.
(java.lang.String, android.os.Bundle)
Related
I have two activities Activity A and Activity B that needs to communicate very frequently, if i will use startActivity on both activities then every times it will create new instances of them.
If i will use launchMode as singleTask then suppose from Activity A i call Activity B then if Activity B doesn't exist in the Task, new Instance of Activity B will be created in the Task and that will be on top of the Task, Now if i will call Activity A from B then Activity B will gets cleared from Task(singleTask makes A as the root Activity).Again calling B from A will create new Instance of B but i want if the the Activities exist in Task then it should not create new Instances.
How do i achieve this ?, Any help will be appreciated.
I don't know your use case why are you trying to have two activity instances at the same time which is against the design of android. You can also use Fragments within your activity to fulfill your purpose.
I think better option is to use observer pattern. Use broadcast receiver to send the message between activities.
My app shows some content (video,pdf,img, etc ) and within every content I can start another content. What I want is to have only "one back history".
For example, if my activity history is like this:
VideoActivityIns1->PdfActivityIns1->VideoActivityIns2
I need to go back from VideoActivityIns2 to PdfActivityIns1, but one step back is should be MainActivity of my app.
How can I do this? Any help would be appreciated
Each activity has activity lifecycle methods you can override to achieve the result you need. Thus, you can either launch Activity2 onResume() on Activity1 onPause(),
http://developer.android.com/training/basics/activity-lifecycle/index.html
or, invoke ActivityManager to detect and manage the other activities.
http://developer.android.com/reference/android/app/ActivityManager.html
You can also make use of intent resolution mechanism to assign several priorities to your activities and then setup intent filters in each activity so you can start activities with a given priority in your code. You can do this either in Java or XML (though I suggest Java). Have a look at the Intent class.
Hi i am new to Android application development.In my Application i have two activity Activity1 and Activity2.From activity1 i call Activity2 as Intent.I want to access activity1 from this Activity(activity2) without going to first activity is there any posible way?Pls guide me
The only thing which make sence is passing data from Activity 1 to Activity 2. To do it just pass some data through the intent:
intent.putExtra("key", "Your data here");
in second activity:
String data = getIntent().getExtra("key");
If this is not the case, then your task is wrong somewhere. When activity gone background, there is no sence to interact with it.
No, there isn't. Activity1 might even have been shut down.
If you want to pass DATA between the two activities, that's of course doable. Either by passing data on with the intent, by using http://developer.android.com/reference/android/content/SharedPreferences.html or any other storage you can access from both activities.
If from your second activity wants to change something on the previous one, then, instead of using
startActivity(...);
you should use
startActivityForResult(...);
Maybe this link can help.
So you have the scenario where you start activity B from activity A and you want to change some parameters when activity B is done ( your changes can't be propagated in real time because you can't be sure what is the state of activity A ). So the best way to implement this is to use activity result - for more info about it check Android: Capturing the return of an activity
If you have several activities onPause() is there a way to finish a specific activity?
edit: so for example, imagine on start activity 1 is called. Then activity 1 uses an intent to go to activity 2. then an update is made to the database and calls activity 1_new again so that it displays the updated database. At that point i want to get rid of the old activity 1.
It depends on what you want to do. You'll need to look at the AndroidManifest.xml spec for activity calls stacks.
Specifically android:launchMode
<activity android:launchMode="singleTop">
Careful though, launchModes are very tricky and can get you into trouble since it also depends on how the activity is launched from the Intent itself.
singleTop will essentially keep only 1 instance of that activity in the stack.
From the Docs:
If an instance of the activity already
exists at the top of the target task,
the system routes the intent to that
instance through a call to its
onNewIntent() method, rather than
creating a new instance of the
activity.
What I ended up doing here was calling startActivityForResult in the first activity. That way I was able to redisplay updated information from the second activity.
How can I know what Activity has started the current Activity? Is there any specific method like, i.e. getIntent().getCallerActivity() or the only way is saving some information within the Intent using putExtra()?
Thanks.
There's getCallingActivity which you can use to get the name of the calling activity if you started the sub-activity with startActivityForResult.