Question

Well I searched a lot, but I didn’t find a precise answer how to export an Activity, so an app can start it with startActivityforResult.

How do I achieve that? Do I have to change the Manifest in some ways?

Answer 1

You need to declare an intent-filter in your Manifest (I took the following example from Barcode Scanner) :

<activity android:name="...">
    <intent-filter>
        <action android:name="com.google.zxing.client.android.SCAN" />
        <category android:name="android.intent.category.DEFAULT" />
    </intent-filter>
</activity>

Then create an intent with the same action string :

Intent intent = new Intent("com.google.zxing.client.android.SCAN");
startActivityForResult(intent, code);

Android should start your activity (or it will show a drop-down box if there are multiple apps sharing the same action string).