Question

I plan to do an app which contains only one activity and without any app icon, where I need to open this activity by using the keypad. Say for example, whenever you dial 12345 my application activity should open without an app icon. Is this possible in Android? How?

Answer 1

You must specify drawable resource for android:icon attribute in application element of AndroidManifest.xml. From documentation:

This attribute must be set as a reference to a drawable resource containing the image (for example “@drawable/icon”). There is no default icon.

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But the drawable specified doesn’t need to be an icon. It can be defined as color in your resources:

<?xml version="1.0" encoding="utf-8"?>
<resources>
   <drawable name="color_icon">#ff0000</drawable>
</resources>

And then specify it in your AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest ...>  
    <application android:icon="@drawable/color_icon" ...>
       ...
    </application>  
</manifest> 

And you’ll see something like this in your application launchpad: