title: Android:add PayPal payments
body: <p>I'm building an Android application, integrated with Paypal.
  I wrote this:</p>
  
  <pre><code>PayPal pp = PayPal.initWithAppID(this, "APP-80W284485P519543T", PayPal.ENV_SANDBOX);
      LinearLayout lay = (LinearLayout)findViewById(R.id.layout_faq);
  
      CheckoutButton launchSimplePayment = pp.getCheckoutButton(this, PayPal.BUTTON_194x37, CheckoutButton.TEXT_PAY);
      launchSimplePayment.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
              PayPalPayment payment = new PayPalPayment();
  
              payment.setSubtotal(new BigDecimal("8.25"));
  
              payment.setCurrencyType("USD");
  
              payment.setRecipient("bss_45@gmail.com");
  
              payment.setPaymentType(PayPal.PAYMENT_TYPE_GOODS);
  
              Intent checkoutIntent = PayPal.getInstance().checkout(payment, getApplicationContext());
  
              startActivityForResult(checkoutIntent, 1);
          }});
      lay.addView(launchSimplePayment);
  </code></pre>
  
  <p>When i run the emulator, the app crashes. Log cat says:</p>
  
  <pre><code>05-03 12:48:41.768: E/AndroidRuntime(748): FATAL EXCEPTION: Thread-85
  05-03 12:48:41.768: E/AndroidRuntime(748): java.lang.NullPointerException
  05-03 12:48:41.768: E/AndroidRuntime(748):  at com.paypal.android.b.e.j(Unknown Source)
  05-03 12:48:41.768: E/AndroidRuntime(748):  at com.paypal.android.b.e.v(Unknown Source)
  05-03 12:48:41.768: E/AndroidRuntime(748):  at com.paypal.android.b.e.c(Unknown Source)
  05-03 12:48:41.768: E/AndroidRuntime(748):  at com.paypal.android.b.f.run(Unknown Source)
  </code></pre>
  
  <p>The library that i've imported is PayPal_MPL.jar.</p>
  
  <p>Have i need to import other jar? or what?</p>
  
  <p>Thanks.</p>