SSL sockets - Java and certificates?

I am trying to implement SSL sockets between an Android application and a Python API.

The code below...

SSLSocketFactory ssf = (SSLSocketFactory) SSLSocketFactory.getDefault();
Socket s = ssf.createSocket("10.0.2.2", 5001);
DataOutputStream myDataOut = new DataOutputStream(s.getOutputStream());
myDataOut.writeUTF("Hello Server");
myDataOut.flush();
myDataOut.close();
s.close();

As you can see it doesn't work:

590.0750 - Establishing connection to ('127.0.0.1', 50888)
590.0970 - Error while connecting
590.0970 - Error information: [SSL: SSLV3_ALERT_CERTIFICATE_UNKNOWN] sslv3 alert certificate unknown (_ssl.c:590)

I believe it's not because I didn't specify the certificate. See a working example in Python for the client:

import socket, ssl, pprint

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

ssl_sock = ssl.wrap_socket(s,
                           ca_certs="server.crt",
                           cert_reqs=ssl.CERT_REQUIRED)

ssl_sock.connect(('localhost', 5001))

print repr(ssl_sock.getpeername())
print ssl_sock.cipher()
print pprint.pformat(ssl_sock.getpeercert())

ssl_sock.write("Hello from the client...")

How to specify certificate in Java like in Python?