小编mkw*_*eid的帖子

美好的一天 .我想使用pepraredStatement插入数据库.但是每当我添加数据库部分(连接和pepraredStatement)时,"UPLOAD"按钮就会没有响应.但当我删除任何与数据库相关的内容时,我的所有按钮都正常工作.你可以在这里找到代码http://pastebin.com/euKdWhr2.

我将非常感谢任何帮助或建议.可能我在数据库部分缺少一些东西.

public void actionPerformed(ActionEvent ev)
        {
            String file = fileField.getText();
            SetGetQuestionFileName pattern = new SetGetQuestionFileName(file);
                ConnectToDatabase database = new ConnectToDatabase();
            try
            {

            ///////// check whether textfile is empty or not 

            if( ev.getActionCommand().equals("UPLOAD"))
            {
                if(fileField.getText().isEmpty())
                {
                    JOptionPane.showMessageDialog(null,"File field can not be empty!!! Please try again.","ALERT", JOptionPane.ERROR_MESSAGE);
                }
                else
                    {
                        File fi = new File(fileField.getText());
                        ////////////////  perform upload 

                        try 
                            {

                    String sql = "INSERT INTO testsystem.questionnaire (category_questions, questions, correct_answer)" + "VALUES (?, ?, ?)";

                    PreparedStatement st =  null; …