How to launch an Activity without a UI?

Question

Is it in any way possible to launch an activity from the main function without having a UI? i.e. is there a way to create a sort of "wrapper" around another activity, i.e. by launching the main activity, it takes you to another activity automatically.

If that is not possible, is there a way to remove the main activity from the stack so that clicking the back button does not take you to a blank UI? Here's an example of what I'm trying to do:

public class WrapperActivity extends Activity {

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        final Intent intent = new Intent(Intent.ACTION_DIAL, Uri.parse("tel:555-1212"));
        startActivity(intent);
    }
}

score 137 · Answer 1 · edited Jun 26 '12 at 11:52

137

Android also provides a theme specifically for this:

android:theme="@android:style/Theme.NoDisplay"

edited Jun 26 '12 at 11:52

yanchenko

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answered Feb 03 '11 at 22:53

Justin

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This works well, but also causes the icon to disappear from the app drawer. To get the icon to appear, you'll need to use Brian515's answer. – Learn OpenGL ES Dec 10 '12 at 23:53
1

I also found that this works, but if I display a progress dialog then it defaults to Holo.Dark which doesn't match the style of the rest of my app. – Andy Johnson Sep 12 '13 at 11:25
1

@LearnOpenGLES I'm using this theme and I still get the icon in the app drawer. I also find it to be a better option, since it sets a bunch of values to NULL, leading me to think that it is more efficient. https://android.googlesource.com/platform/frameworks/base/+/refs/heads/master/core/res/res/values/themes.xml/refs/heads/master/core/res/res/values/themes.xml – givanse Nov 10 '13 at 21:28
@AndyJohnson You can style your progress dialogs when you create them, so you could default it Holo.Light (or any other theme) if you want. – Justin Nov 12 '13 at 23:00
@LearnOpenGLES This question has nothing to do with the icon being in the app drawer, your link is broken, and setting values to NULL doesn't generally make things more efficient... – Justin Nov 12 '13 at 23:01
Do Not Forget to put `finish()` at the end, otherwise acts weird. – Jemshit Jul 10 '15 at 14:26
4

For this to work, your activity has to inherit from Activity, not AppCompactActivity. – Kof Jul 24 '15 at 21:23
4

@Kof: you can also just copy the contents of `Theme.NoDisplay` (only 6 attributes) to any extension of `Theme.AppCompat.*` in order to create your own `Theme.AppCompat.NoDisplay` that works with `AppCompatActivity`. – MH. Sep 07 '15 at 15:25
Its not work in 6.0 Marshmellow, Can you pleas provide solution for this version? – Hardik Chauhan May 09 '16 at 06:46
1

FYI, If anyone trying to set theme as "NoDisplay" on target version higher than 23, please revisit code once again. reference Link: https://commonsware.com/blog/2015/11/02/psa-android-6p0-theme.nodisplay-regression.html – rk_P Apr 16 '18 at 16:06

score 55 · Answer 2 · edited Jun 26 '12 at 11:52

55

In your manifest, when you declare the activity, use theme "@android:style/Theme.Translucent.NoTitleBar"

Ex:

<activity android:name="yourActivityName" android:label="@string/app_name" android:theme="@android:style/Theme.Translucent.NoTitleBar">

edited Jun 26 '12 at 11:52

yanchenko

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answered Apr 24 '10 at 14:31

strange quark

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This is the right answer if you also need the app to appear in the app drawer. – Learn OpenGL ES Dec 10 '12 at 23:53
4

This still opens invisible UI, which you have to press back before you continue using phone – Jemshit Jul 10 '15 at 14:18

score 39 · Accepted Answer · answered Apr 24 '10 at 11:26

39

You need to add the Intent flag,

intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

Or

call "finish();" after firing the intent.

answered Apr 24 '10 at 11:26

Vishwanath

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I'm not sure that the `FLAG_ACTIVITY_CLEAR_TOP` trick will work here, because the `Activity` being started will be from another application. `finish()` should definitely work, though. – CommonsWare Apr 24 '10 at 11:42
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Added finish(); and Translucent.NoTitleBar to manifest. Works like a charm. – fjmustak Apr 25 '10 at 07:58
@Vishwanath Intent basically not support finish(). can u detailed, where i can call finish and how? – user170317 Nov 14 '12 at 15:19
2

You call `finish()` at the end of the Activity's `onCreate()` method, just before it returns. – intrepidis May 11 '15 at 20:52

score 14 · Answer 4 · answered Jun 15 '17 at 10:04

14

Just in case you are using Android 6.0+ or Target SDK is 23+, having a theme android:theme = "@android:style/Theme.NoDisplay" will lead to a crash with error did not call finish() prior to onResume() completing. This in fact is a bug recognised by Google developers here.

So it is recommended to use an activity with following theme as a workaround.

android:theme = "@android:style/Theme.Translucent.NoTitleBar"

answered Jun 15 '17 at 10:04

arunwithasmile

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you can start a thread or runnable or service or whatever and call finish in onCreate – SAIR Dec 29 '17 at 17:19

score 8 · Answer 5 · edited Feb 27 '15 at 17:22

8

I think this would help you a lot:

<activity  android:name = "MyActivity" 
          android:label = "@string/app_name" 
          android:theme = "@android:style/Theme.NoDisplay" >

edited Feb 27 '15 at 17:22

Steve Blackwell

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answered Feb 16 '15 at 00:34

Fermin Genao

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Welcome to Stack Overflow! Stack Overflow generally works in English; please make sure your post is as useful as possible to others by translating it. – Nathan Tuggy Feb 16 '15 at 00:53
When using this method make sure to pay attention to arunwithasmile's comment – marchinram Jul 28 '17 at 16:41
Where would I put this? – d51 Nov 19 '20 at 08:00

score 8 · Answer 6 · edited Nov 24 '11 at 21:05

Using

<activity android:name="yourActivityName" android:label="@string/app_name" android:theme="@android:style/Theme.Translucent.NoTitleBar">

mentioned by Brian515 works great. This method is useful for creating an entry point Activity that decides on which activity to call, start, services, etc without having to show a UI to the user. Remember to use finish() after you have started your intent.

score 5 · Answer 7 · answered Dec 10 '19 at 12:53

I am using AppCompatActivity and the solutions provided in this SO did not solve my problem. Here is what worked for me.

I added the following in my styles.xml.

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <!-- Customize your theme here. -->
</style>

<style name="AppTheme.NoDisplay">
    <item name="android:windowBackground">@null</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowIsTranslucent">true</item>
    <item name="android:windowAnimationStyle">@null</item>
    <item name="android:windowDisablePreview">true</item>
    <item name="android:windowNoDisplay">true</item>
</style>

Then, for any activity that I want to disable the display, I modified like so:

<activity 
    android:name=".NoDisplayActivity"
    android:theme="@style/AppTheme.NoDisplay">

Cheers!

you mean the androidmanifest.xaml file? I am not able to edit that file — d51, Nov 19 '20 at 23:36
I found out another way, but maybe later I'll ask a question bout it — d51, Nov 20 '20 at 22:22

score 4 · Answer 8 · answered Aug 05 '15 at 16:51

4

In your manifest add @android:style/Theme.Translucent.NoTitleBar" as mentioned in some of the answers above.

Also remove the setContentView(R.layout.your_activity); line from your activity.java file.

answered Aug 05 '15 at 16:51

Vipul Behl

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score 3 · Answer 9 · edited Aug 17 '13 at 23:11

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I had used moveTaskToBack(true) in onResume() to put the entire activity stack in background.

edited Aug 17 '13 at 23:11

Sled

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answered Aug 17 '13 at 22:49

Tarak

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I had to use this method because I want the activity to show some times but not other times. – Randy Dec 04 '16 at 15:26

score 2 · Answer 10 · edited May 23 '17 at 12:26

2

Looks similar to the question asked here: Removing an activity from the history stack

If it is, then you can use:

FLAG_ACTIVITY_NO_HISTORY

This should work to wipe activities off of the stack.

If you need to exclude from recent apps (long press home key) you can use this flag:

FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS

edited May 23 '17 at 12:26

Community

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answered Oct 26 '11 at 05:17

Sreedevi J

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This has nothing to with removing an activity from the history stack. – Justin Nov 12 '13 at 23:02
@Justin I'm quite sure that the question has this part: "If that is not possible, is there a way to remove the main activity from the stack so that clicking the back button does not take you to a blank UI?" Which I believe, is rather closely tied to the history stack, but I could be mistaken. – Sreedevi J Nov 14 '13 at 04:17
I apologize... I didn't notice the last two sentences in the question. In any case, I don't think this solves the problem. I may be mistaken but I don't think either of these flags would remove the activity from the back stack (e.g. pressing the back button would still take the user to the blank UI) – Justin Nov 26 '13 at 18:54
@Justin, no, it doesn't take user back to a blank UI. This flag or the manifest equivalent will not add the activities to the stack, so there is nothing to go back to. – Sreedevi J Nov 28 '13 at 03:07

score 2 · Answer 11 · answered Dec 26 '11 at 21:44

2

If you are not interacting with the UI, what you are trying to do sounds more like an android service.

answered Dec 26 '11 at 21:44

sebastianf182

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In some cases yes.... but not in all cases. It seemed to be something that came up often-enough that the Android framework engineers created a specific theme for activities that don't have a UI. – Justin Feb 01 '12 at 19:43
If I use, for instance, a third-party library for selecting fonts or colors, it is typically designed to require the Activity that launches it to implement some callback interface. But I may be launching the color picker from a popup window. If I want to encapsulate the entire flow in the code for my popup window, rather than polluting my main Activity's interface, then I need a temporary (invisible) activity to act as the listener for the color chooser – Stevey Mar 23 '17 at 20:53

How to launch an Activity without a UI?

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