Always-on VPN switch on programmatically android

Can Always-on VPN switch be on programmatically?

I have added the device admin permission. After that i have set always on in with device admin

mDPM = (DevicePolicyManager) getSystemService(Context.DEVICE_POLICY_SERVICE);
    mDeviceAdminSample = new ComponentName(this, DeviceAdminReceiver.class);
    isAdminApp = mDPM.isAdminActive(mDeviceAdminSample);

    if (isAdminApp) {
        try {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                mDPM.setAlwaysOnVpnPackage(mDeviceAdminSample,"", true);
            }
        } catch (PackageManager.NameNotFoundException namenotfoundexception) {
            namenotfoundexception.printStackTrace();
        } catch (Exception ex) {
        }
    }

but it's not enabling the always on.

i have added package name insted of

mDPM.setAlwaysOnVpnPackage(mDeviceAdminSample,"my.app.package.name", true);

but still not enabling the switch.

Then what this code is doing? How can i enable it programatically?

I want this to be like below image

from Always-on VPN switch on programmatically android