exception could not create connection to database server

Question

when i run my project sometimes message appear which like "exception could not create connection to database server" I'm using net beans and MySQL and i added MySQL_connector jar file to library

import AnswerAnalysis.CheckConstraint;
import AnswerAnalysis.ConstStatus;
import RetriveFromDataBase.Retirving_from_skills;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;
import AnswerAnalysis.ValueFeature;

import AnswerAnalysis.StudentAnswerElement;

Answer 1

If your code sometimes work and sometimes don't, without changes (ie. using the same jar/compiled class), so probably you have network problems.

Does MySQL is a available to other people? It could be misconfigured and it may be able to serve many concurrent sessions.