public class MyActivity extends Activity {private static final String TAG = "MainActivity";private Button button;private static final int REQUEST_CODE_PAYMENT = 1;private static PayPalConfiguration paypalConfig = new PayPalConfiguration().environment(PayPalConfiguration.ENVIRONMENT_SANDBOX).clientId(Config.PAYPAL_CLIENT_ID);private List<PayPalItem> productsInCart = new ArrayList<PayPalItem>();@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);button = (Button) findViewById(R.id.button);button.setOnClickListener(new View.OnClickListener() {public void onClick(View v) {addToCart(new Product("1", "sinny", "fredric_sinny", null, new BigDecimal(1), "1232131"));PayPalPayment thingsToBuy = prepareFinalCart();Intent intent = new Intent(MyActivity.this,PaymentActivity.class);intent.putExtra(PayPalService.EXTRA_PAYPAL_CONFIGURATION, paypalConfig);intent.putExtra(PaymentActivity.EXTRA_PAYMENT, thingsToBuy);startActivityForResult(intent, REQUEST_CODE_PAYMENT);}});}private PayPalPayment prepareFinalCart() {PayPalItem[] items = new PayPalItem[productsInCart.size()];items = productsInCart.toArray(items);// Total amountBigDecimal subtotal = PayPalItem.getItemTotal(items);// If you have shipping cost, add it hereBigDecimal shipping = new BigDecimal("0.0");// If you have tax, add it hereBigDecimal tax = new BigDecimal("0.0");PayPalPaymentDetails paymentDetails = new PayPalPaymentDetails(shipping, subtotal, tax);BigDecimal amount = subtotal.add(shipping).add(tax);PayPalPayment payment = new PayPalPayment(amount,Config.DEFAULT_CURRENCY,"Description about transaction. This will be displayed to the user.",PayPalPayment.PAYMENT_INTENT_SALE);payment.items(items).paymentDetails(paymentDetails);payment.custom("This is text that will be associated with the payment that the app can use.");return payment;}public void addToCart(Product product) {PayPalItem item = new PayPalItem(product.getName(), 1,product.getPrice(), Config.DEFAULT_CURRENCY, product.getSku());productsInCart.add(item);Toast.makeText(getApplicationContext(),item.getName() + " added to cart!", Toast.LENGTH_SHORT).show();}@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {super.onActivityResult(requestCode, resultCode, data);PaymentConfirmation confirm = data.getParcelableExtra(PaymentActivity.EXTRA_RESULT_CONFIRMATION);String paymentId;try {paymentId = confirm.toJSONObject().getJSONObject("response").getString("id");String payment_client = confirm.getPayment().toJSONObject().toString();Log.e(TAG, "paymentId: " + paymentId + ", payment_json: "+ payment_client);} catch (JSONException e) {// TODO Auto-generated catch block
            e.printStackTrace();}}
}