The solution of @Chrispix is dangerous! Trusting all certificates allows anybody to do a man in the middle attack! Just send ANY certificate to the client and it will accept it!
Add your certificate(s) to a custom trust manager like described in this post: Trusting all certificates using HttpClient over HTTPS
Although it is a bit more complex to establish a secure connection with a custom certificate, it will bring you the wanted ssl encryption security without the danger of man in the middle attack!