java - "Textfield validation not working properly"

Question

验证部分出现问题，没有显示有关空字段的消息。立即帮助

私有(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，以便在给定空白表示某个值的情况下，删除任何空白。

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。