USB Permissions without prompt

I have 2 activities within my app. Say FirstActivity and SecondActivity. FirstActivity is the MAIN and LAUNCHER activity. SecondActivity uses usb devices. I want the prompt for USB permission to appear only once within lifetime of the app.

If there was only one Activity, the following lines in manifest solved my purpose:

<activity android:name=".FirstActivity">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
        <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
    </intent-filter>

    <meta-data
        android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
        android:resource="@xml/usb_device_filter" />
</activity>

This was doing the following:

Launching FirstActivity whenever usb device (mentioned in xml) is connected is app is not already open.
Prompt for usb device permission appears only once.

How do I modify this to achieve the following:

If SecondActivity is already running and a new usb device is attached, I must be able to use the device without relaunching the app. So I have written a broadcast receiver for the same as follows:

public class TriggerReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals(UsbManager.ACTION_USB_DEVICE_ATTACHED)) { 
        read connected usb devices and register serial port call listener back.
    }
}

But the problem is FirstActivity gets relaunched again when usb device is attached while SecondActivity is running. How do I avoid this ?

Will add more information if needed. Would be thankful for any help.

Solution

Try "remove" intent filter <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" /> from FirstActivity like in this question

Update

FirstActivity triggers on every USB_DEVICE_ATTACHED (even SecondActivity is running) because You set <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" /> filter for it in AndroidManifest.xml file. So You should disable this filter when SecondActivity running. You can do this by that way:

1) add (e.g. AliasFirstActivity) in AndroidManifest.xml to your FirstActivity and move <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" /> filter to alias description (You should remove <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />from FirstActivity description) like that:

        <activity-alias
            android:targetActivity=".FirstActivity"
            android:name=".AliasFirstActivity"
            android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>

            <intent-filter>
                <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
            </intent-filter>

            <meta-data android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
                       android:resource="@xml/device_filter" />
        </activity-alias>

2) add this code to onCreate() (or to onResume()) of SecondActivity

PackageManager pm = getApplicationContext().getPackageManager();
        ComponentName compName =
                new ComponentName(getPackageName(), getPackageName() + ".AliasFirstActivity");
        pm.setComponentEnabledSetting(
                compName,
                PackageManager.COMPONENT_ENABLED_STATE_DISABLED,
                PackageManager.DONT_KILL_APP);

to suppress intent filter USB_DEVICE_ATTACHED for FirstActivity. You should have in SecondActivity something like that:

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);

        triggerReceiver = new TriggerReceiver();

        IntentFilter filter = new IntentFilter();
        filter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
        registerReceiver(triggerReceiver, filter);

        PackageManager pm = getApplicationContext().getPackageManager();
        ComponentName compName =
                new ComponentName(getPackageName(), getPackageName() + ".AliasFirstActivity");
        pm.setComponentEnabledSetting(
                compName,
                PackageManager.COMPONENT_ENABLED_STATE_DISABLED,
                PackageManager.DONT_KILL_APP);
    }

That should solve Your issue. 3) if it is needed, You can restore <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" /> filter for FirstActivity in onDestroy() (or in onPause()) of SecondActivity by using this code:

    PackageManager pm = getApplicationContext().getPackageManager();
    ComponentName compName =
            new ComponentName(getPackageName(), getPackageName() + ".AliasFirstActivity");
    pm.setComponentEnabledSetting(
            compName,
            PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
            PackageManager.DONT_KILL_APP);