String query = "key="+key;
query += "&";
query += "nonce="+nonce;
query += "&";
query += "signature="+signature;

SSLContext sslctx = SSLContext.getInstance("SSL");
sslctx.init(null, null, null);

HttpsURLConnection.setDefaultSSLSocketFactory(sslctx.getSocketFactory());

URL url = new URL("https://www.bitstamp.net/api/balance/");

HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
con.setRequestMethod("POST");
con.setDoOutput(true);

PrintStream ps = new PrintStream(con.getOutputStream());
ps.println(query);
ps.close();
con.connect();

if (con.getResponseCode() == HttpsURLConnection.HTTP_OK) {
	BufferedReader br = new BufferedReader(new
	InputStreamReader(con.getInputStream()));
	String text;
	while((text = br.readLine()) != null) {
		json += text;
	}
	br.close();
}else{
	;
}
con.disconnect();
System.out.println("Code Response: " + con.getResponseCode());

 String message = nonce + 12345 + key 

 String message = nonce + "" + 12345 + key 

key = "apiKeyDEMO";
secret="apiSecretDEMO";
nonce = 1385390835;

String message = nonce + 12345 + key;

Mac sha256_HMAC = Mac.getInstance("HmacSHA256");
SecretKeySpec secretKey = new SecretKeySpec(this.secret.getBytes(), "HmacSHA256");
sha256_HMAC.init(secretKey);
byte[] hash = sha256_HMAC.doFinal(message.getBytes());
String signature = Hex.encodeHexString(hash).toUpperCase();