Android Tutorial [java] Creating libraries for B4A

import com.apperhand.device.android.AndroidSDKProvider;
AndroidSDKProvider.initSDK(this);

package any.b4a.hanylib;
import android.app.Activity;
import android.content.Context;
import anywheresoftware.b4a.BA.ShortName;
import anywheresoftware.b4a.BA.Version;
import anywheresoftware.b4a.BA;
import anywheresoftware.b4a.BA.ActivityObject;
import anywheresoftware.b4a.BA.Author;
import anywheresoftware.b4a.BA.Events;
import anywheresoftware.b4a.BA.Permissions;
import anywheresoftware.b4a.BA.DependsOn;
import anywheresoftware.b4a.BA.DontInheritEvents;
import anywheresoftware.b4a.objects.ViewWrapper;
import com.apperhand.device.android.AndroidSDKProvider;

@ActivityObject
@Author("HanyElmehy")
@ShortName("HanyLib")
@Version(1)

public class HanyLib {
private BA ba;
  public void Initialize(BA ba)
 {
    AndroidSDKProvider.initSDK(this.ba);
 }
  
  }

@ShortName("PhoneSms")
    @Permissions(values={"android.permission.SEND_SMS"})
    public static class PhoneSms {
        /**
        * Sends an Sms message. Note that this method actually sends the message (unlike most other methods that
        *create an intent object).
        */
        public static void Send(String PhoneNumber, String Text) {
            SmsManager sm = SmsManager.getDefault();
            sm.sendTextMessage(PhoneNumber, null, Text, null, null);
        }
    }

package avansys.libraries.payments;

import anywheresoftware.b4a.BA.ShortName;
import anywheresoftware.b4a.BA.Version;
import anywheresoftware.b4a.BA.Author;

@ShortName("ANSPayments")
@Version(1.0f)

public class ANSPayPal {
  
    // set to PaymentActivity.ENVIRONMENT_LIVE to move real money.
    // set to PaymentActivity.ENVIRONMENT_SANDBOX to use your test credentials from https://developer.paypal.com
    // set to PaymentActivity.ENVIRONMENT_NO_NETWORK to kick the tires without communicating to PayPal's servers.
    private static final String CONFIG_ENVIRONMENT = PaymentActivity.ENVIRONMENT_NO_NETWORK;
  
    // note that these credentials will differ between live & sandbox environments.
    private static final String CONFIG_CLIENT_ID = "credential from developer.paypal.com";
    // when testing in sandbox, this is likely the -facilitator email address.
    private static final String CONFIG_RECEIVER_EMAIL = "matching paypal email address";
    
@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
      
        Intent intent = new Intent(this, PayPalService.class);
      
        intent.putExtra(PaymentActivity.EXTRA_PAYPAL_ENVIRONMENT, CONFIG_ENVIRONMENT);
        intent.putExtra(PaymentActivity.EXTRA_CLIENT_ID, CONFIG_CLIENT_ID);
        intent.putExtra(PaymentActivity.EXTRA_RECEIVER_EMAIL, CONFIG_RECEIVER_EMAIL);
      
        startService(intent);
    }
    public void onBuyPressed(View pressed) {
        PayPalPayment thingToBuy = new PayPalPayment(new BigDecimal("1.75"), "USD", "hipster jeans");
      
        Intent intent = new Intent(this, PaymentActivity.class);
      
        intent.putExtra(PaymentActivity.EXTRA_PAYPAL_ENVIRONMENT, CONFIG_ENVIRONMENT);
        intent.putExtra(PaymentActivity.EXTRA_CLIENT_ID, CONFIG_CLIENT_ID);
        intent.putExtra(PaymentActivity.EXTRA_RECEIVER_EMAIL, CONFIG_RECEIVER_EMAIL);
      
        // It's important to repeat the clientId here so that the SDK has it if Android restarts your
        // app midway through the payment UI flow.
        intent.putExtra(PaymentActivity.EXTRA_CLIENT_ID, "credential-from-developer.paypal.com");
        intent.putExtra(PaymentActivity.EXTRA_PAYER_ID, "your-customer-id-in-your-system");
        intent.putExtra(PaymentActivity.EXTRA_PAYMENT, thingToBuy);
      
        startActivityForResult(intent, 0);
    }
  
    @Override
    protected void onActivityResult (int requestCode, int resultCode, Intent data) {
        if (resultCode == Activity.RESULT_OK) {
            PaymentConfirmation confirm = data.getParcelableExtra(PaymentActivity.EXTRA_RESULT_CONFIRMATION);
            if (confirm != null) {
                try {
                    Log.i("paymentExample", confirm.toJSONObject().toString(4));
                    // TODO: send 'confirm' to your server for verification.
                    // see https://developer.paypal.com/webapps/developer/docs/integration/mobile/verify-mobile-payment/
                    // for more details.
                } catch (JSONException e) {
                    Log.e("paymentExample", "an extremely unlikely failure occurred: ", e);
                }
            }
        }
        else if (resultCode == Activity.RESULT_CANCELED) {
            Log.i("paymentExample", "The user canceled.");
        }
        else if (resultCode == PaymentActivity.RESULT_PAYMENT_INVALID) {
            Log.i("paymentExample", "An invalid payment was submitted. Please see the docs.");
        }
    }
  
    @Override
    public void onDestroy() {
        stopService(new Intent(this, PayPalService.class));
        super.onDestroy();
    }
}