Setup paypal in your android code

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

<service
       android:name="com.paypal.android.sdk.payments.PayPalService"
       android:exported="false" />
   <activity android:name="com.paypal.android.sdk.payments.PaymentActivity" />
   <activity android:name="com.paypal.android.sdk.payments.LoginActivity" />
   <activity android:name="com.paypal.android.sdk.payments.PaymentMethodActivity" />
   <activity android:name="com.paypal.android.sdk.payments.PaymentConfirmActivity" />
   <activity android:name="com.paypal.android.sdk.payments.PayPalFuturePaymentActivity" />
   <activity android:name="com.paypal.android.sdk.payments.FuturePaymentConsentActivity" />
   <activity android:name="com.paypal.android.sdk.payments.FuturePaymentInfoActivity" />
   <activity
       android:name="io.card.payment.CardIOActivity"
       android:configChanges="keyboardHidden|orientation" />
   <activity android:name="io.card.payment.DataEntryActivity" />

//set the environment for production/sandbox/no netowrk
 private static final String CONFIG_ENVIRONMENT = PayPalConfiguration.ENVIRONMENT_PRODUCTION;

intent.putExtra(PayPalService.EXTRA_PAYPAL_CONFIGURATION, config);
startService(intent);

PayPalPayment thingToBuy = new PayPalPayment(new BigDecimal(1),"USD", "androidhub4you.com",
                                 PayPalPayment.PAYMENT_INTENT_SALE);
                             Intent intent = new Intent(MainActivity.this, PaymentActivity.class);
                             intent.putExtra(PaymentActivity.EXTRA_PAYMENT, thingToBuy);

                             startActivityForResult(intent, REQUEST_PAYPAL_PAYMENT);

@Override
          protected void onActivityResult(int requestCode, int resultCode, Intent data) {
              if (requestCode == REQUEST_PAYPAL_PAYMENT) {
                  if (resultCode == Activity.RESULT_OK) {
                      PaymentConfirmation confirm = data
                              .getParcelableExtra(PaymentActivity.EXTRA_RESULT_CONFIRMATION);
                      if (confirm != null) {
                          try {
                          System.out.println("Responseeee"+confirm);
                              Log.i("paymentExample", confirm.toJSONObject().toString());
                           
                              JSONObject jsonObj=new JSONObject(confirm.toJSONObject().toString());
                             
                              String paymentId=jsonObj.getJSONObject("response").getString("id");
                              System.out.println("payment id:-=="+paymentId);
                              Toast.makeText(getApplicationContext(), paymentId, Toast.LENGTH_LONG).show(); 
                          } 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_EXTRAS_INVALID) {
                      Log.i("paymentExample", "An invalid Payment was submitted. Please see the docs.");
                  }
              }
             
              
        }