“文本域验证工作不正常”

Question

验证部分出现问题，没有关于空字段的消息显示。立即提供帮助

private void addbtnActionPerformed(java.awt.event.ActionEvent evt) {

    try{

    Class.forName("com.mysql.cj.jdbc.Driver");

    Connection con =DriverManager.getConnection("jdbc:mysql://localhost:3306/dbfinance","root","1234");

    String sql="insert into util(type_,due_date,month_,amount,units,status_) values(?,?,?,?,?,?)";

    PreparedStatement pstm =con.prepareStatement(sql);

    pstm.setString(1,electype.getSelectedItem().toString());

    pstm.setString(2,date.getText().toString());

    pstm.setString(3,jComboBox1.getSelectedItem().toString());

    pstm.setDouble(4,Double.parseDouble(amount.getText()));

    pstm.setString(5,unit.getText());

    pstm.setString(6,status.getText());

   pstm.executeUpdate();

   JOptionPane.showMessageDialog(null, "success");

   con.close();

        }catch(Exception e){

            JOptionPane.showMessageDialog(null,e);

        }

     if(amount.getText().isEmpty()||unit.getText().isEmpty()||status.getText().isEmpty()){

            JOptionPane.showMessageDialog(null,"please enter data");

           // errorname2.setText("fill this field");

    }        

}

Answer 1

在验证之前，您不应该将数据插入数据库。仅当数据不为空时才插入数据。至于检查数据是否为空，最好修剪文本，以便在给定的空白表示某个值的情况下，任何空白都会被修剪掉。if(amount.getText().trim().isEmpty()||unit.getText().trim().isEmpty()||            status.getText().trim().isEmpty()){        JOptionPane.showMessageDialog(null,"please enter data");        // errorname2.setText("fill this field");    }请确保您将修剪后的数据插入到数据库中。

Answer 2

在应用语句之前尝试验证您的金额字段是否为空try-catch：if(amount.getText().isEmpty()||unit.getText().isEmpty()||status.getText().isEmpty()){        JOptionPane.showMessageDialog(null,"please enter data");        // errorname2.setText("fill this field");    }else{        try{            Class.forName("com.mysql.cj.jdbc.Driver");            Connection con =DriverManager.getConnection("jdbc:mysql://localhost:3306/dbfinance","root","1234");            String sql="insert into util(type_,due_date,month_,amount,units,status_) values(?,?,?,?,?,?)";            PreparedStatement pstm =con.prepareStatement(sql);            pstm.setString(1,electype.getSelectedItem().toString());            pstm.setString(2,date.getText().toString());            pstm.setString(3,jComboBox1.getSelectedItem().toString());            pstm.setDouble(4,Double.parseDouble(amount.getText()));            pstm.setString(5,unit.getText());            pstm.setString(6,status.getText());            pstm.executeUpdate();            JOptionPane.showMessageDialog(null, "success");            con.close();        }catch(Exception e){            JOptionPane.showMessageDialog(null,e);        }    }