session expired and Invalid session credentials in Response

session is vaid for few mins but req key is valid for almost whole day. so you can serialize usermodel parameters and deserialize it.please refer below code.

if(kiteConnect!=null)
{
return kiteConnect;
}
else
{
// First you should get request_token, public_token using kitconnect login and then use request_token, public_token, api_secret to make any kiteconnect api call.
// Initialize KiteSdk with your apiKey.
KiteConnect kiteconnect = new KiteConnect("xxx");

// set userId
kiteconnect.setUserId("xxxx");
String url = kiteconnect.getLoginUrl();
System.out.println(url);

// Set session expiry callback.
kiteconnect.registerHook(new SessionExpiryHook() {
@Override
public void sessionExpired() {
System.out.println("session expired");
}
});

SaveToken token = new SaveToken();
UserModel userModel = null;
if(token.getFile())
{
userModel = token.deSerializeUserModel();
}
else
{
try {
userModel = kiteconnect.requestAccessToken(new Scanner(System.in).next(), "xxxxx");
} catch (JSONException | KiteException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

token.serializeUserModel(userModel);
}
kiteconnect.setAccessToken(userModel.accessToken);
kiteconnect.setPublicToken(userModel.publicToken);
setKiteConnect(kiteconnect);
return kiteconnect;