com.mysql.jdbc.exceptions.jdbc4。MySQLIntegrityConstraintViolationException:列“id”不能为空?

im having difficulty inserting datas to database table from java classes. I'm getting "Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Column 'id' cannot be null"... I did some digging and couldn't figure it out. Let me post my codes... before that i explain what i want to do... This project contains Servlet class,JSP , and java classes. I'm using JSP html Form to get datas and records them to into a database. Codes here...im having difficulty inserting datas to databas