// Build the void transaction
private static final int VOID_REQUEST_CODE = 4;
   private void startVoid() {
       // Build the void request
       MyPOSVoid voidEx = MyPOSVoid.builder()
               .STAN(27)
               .authCode("VISSIM")
               .dateTime("180129123753")
   	//.voidLastTransactionFlag(true) // this may void last transaction initialized by this terminal
               .build();
   			
   	// Start the void transaction
   	MyPOSAPI.openVoidActivity(MainActivity.this, voidEx, VOID_REQUEST_CODE, true);
   }

@Override
	void onActivityResult(int requestCode, int resultCode, Intent data) {
	    if (requestCode == VOID_REQUEST_CODE) {
			// The transaction was processed, handle the response
			if (resultCode == RESULT_OK) {
				// Something went wrong in the Payment core app and the result couldn't be returned properly
				if (data == null) {
					Toast.makeText(this, "Transaction cancelled", Toast.LENGTH_SHORT).show();
					return;
				}
				int transactionResult = data.getIntExtra("status", TransactionProcessingResult.TRANSACTION_FAILED);

				Toast.makeText(this, "Void transaction has completed. Result: " + transactionResult, Toast.LENGTH_SHORT).show();

				// TODO: handle each transaction response accordingly
				if (transactionResult == TransactionProcessingResult.TRANSACTION_SUCCESS) {
					// Transaction is successful
				}
			} else {
				// The user cancelled the transaction
				Toast.makeText(this, "Transaction cancelled", Toast.LENGTH_SHORT).show();
			}
		}
    }