Byte to Int; Bluetooth

Hey guys,

I want to send a number from my smartphone to my arduino Uno. I use the appinventor and a HC-05 bluetooth module. If I click on a button at the app, I’m going to send 1 Byte. If I show the recieved message on the Serial monitor, I get the right number. But if I print the Integer value of the recieved message, I only get a -1. If I print the Byte number, I get a 255.
How can I get the right Integer value for further calculations?

Thank you!!!

Unbenannt1.PNG

You can't read the serial twice to get the same value. Also, if you just check for availability (not the amount), you can't read more then once inside the while.

So you're just printing a part of the buffer that's not filled.