Android : Presenting transparent activity causes crash

Question

Basically, I have an app with two Activities.

#1 - MainActivity
This has a solid black background and a button.
When the button is pressed TransparentActivity should be presented.

#2 - TransparentActivity
I want this to be transparent (so the phones normal UI can be seen through).

I've tried using the following code:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setTheme(android.R.style.Theme_Translucent);
    setContentView(R.layout.activity_trick);
}

But it causes the app to crash with an NullPointerException.

Please have a look at http://stackoverflow.com/questions/2176922/how-to-create-transparent-activity-in-android I hope this helps Regards — Androidme, Jan 16 '14 at 02:39
If I apply the Theme to MainActivity it gets transparent, but if I set the TransparentActivity's theme to be transparent it crashes. — Jakob Halskov, Jan 16 '14 at 02:51
From a user called Max - AppCompatActivity hasn't the Theme_Translucent(maybe the Theme_Translucent is null),you should create your own style — WhatsThePoint, Nov 29 '17 at 08:36

Shobhit Puri · Accepted Answer · 2014-01-16T03:08:37.400

2

Try1:

Make super.onCreate(savedInstanceState); call after setTheme(android.R.style.Theme_Translucent);. So do as:

setTheme(android.R.style.Theme_Translucent);
super.onCreate(savedInstanceState);

Try 2:

If that doesn't work, I find the following way easiest to make my activity transparent:

<activity android:name=".your.activity.declaration.here" 
android:theme="@android:style/Theme.Translucent.NoTitleBar" />

Basically add android:theme="@android:style/Theme.Translucent.NoTitleBar" to your activity declaration in manifest. I can see that you are trying to do a similar thing programatically but by specifying it in manifest never crashed for me. If it does, then there might be other reasons.

Hope it helps.

edited Jan 16 '14 at 03:08

answered Jan 16 '14 at 02:53

Shobhit Puri

25,769
11
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Thanks for your suggestions; Try 1 did the same and Try 2 simply made the app unresponsive when tapping the button. I have a lot of iOS experience but is very new to Android Development. – Jakob Halskov Jan 16 '14 at 03:11
For 1) Can you post the stacktrace/log please? For 2) By unresponsive you mean that nothing happen when you click the button or it hangs? – Shobhit Puri Jan 16 '14 at 03:16
Update: 2) almost works - the second activity is shown with a transparent background. But it is on top of the first. The goal is to see the 'home screen' of the Android Phone through the TransparentActivity (having MainActivity being 100% invisible so to speak) – Jakob Halskov Jan 16 '14 at 03:17
Is your second `TransparentActivity` are you using `android:width="match_parent` and `android:height="match_parent"` in the outermost layout of the layout xml file? If yes change them to `wrap_content`. This will only cover the necessary space. Rest of the `MainActivity` will be visible then. – Shobhit Puri Jan 16 '14 at 03:24
I want to do the opposite :) Making the TransparentActivity transparent and MainActivity should not be seen at all. So the user will see the content of TransparentActivity and under that the normal Android UI. – Jakob Halskov Jan 16 '14 at 03:26
You must be using intents to start the second activity. So before you start the `TransparentActivity` from the `MainActivity`, call `MainActivity.finish()`( after calling `startActivity(..)` function). Your MainActivity will end and a new activity will start which will be transparent. – Shobhit Puri Jan 16 '14 at 03:29
Great it works, apart from the fact I can't go back to the MainActivity since I've finished it? – Jakob Halskov Jan 16 '14 at 03:42
It depends when do you want to go back to the `MainActivity`. If you want to go to the main activity when you press the `back` button, then override the `onBackPressed` function from inside `Activity` and again start the `MainActivity` using intent. Otherwise you can again start it from any button press etc. Glad it helped. Feel free to upvote/accept the answer :) – Shobhit Puri Jan 16 '14 at 03:45

score 0 · Answer 2 · edited Nov 29 '17 at 09:42

0

AppCompatActivity hasn't the Theme_Translucent(maybe the Theme_Translucent is null),you should create your own style.

edited Nov 29 '17 at 09:42

user4261201

2,324
19
26

answered Nov 29 '17 at 08:16

Max

1

This does not provide an answer to the question it is more of a comment, when you have hit 50 reputation you can [comment everywhere](https://stackoverflow.com/help/privileges/comment) for now i have added the comment for you – WhatsThePoint Nov 29 '17 at 08:35

Android : Presenting transparent activity causes crash

2 Answers2