如何将 integer 数据从数据库带到 swing 用户界面中的 JTextField

Question

I tried making a swing user interface component which have two TextField one take the name of product for which it returns the price of product present in database. There are some mistakes in code please refer some solution. code is as follow:

class Swingui implements ActionListener
{
    JFrame jf=new JFrame("PRODUCT DETAILS");
    JLabel jl1=new JLabel("Product:");
    JTextField jtf1=new JTextField();
    JTextField jtf2=new JTextField();
    JLabel jl2=new JLabel("Price:");
    JButton jb=new JButton("enter");
    Swingui()
    {
        jf.setSize(500,500);
        jf.setVisible(true);
        jf.setLayout(null);
        jf.setDefaultCloseOperation(jf.EXIT_ON_CLOSE);
        jl1.setBounds(50,70,100,30);
        jf.add(jl1);
        jtf1.setBounds(50,100,100,30);
        jf.add(jtf1);
        jl2.setBounds(50,150,100,30);
        jf.add(jl2);
        jb.setBounds(50,250,100,30);
        jf.add(jb);
        jtf2.setBounds(50,200,100,30);
        jf.add(jtf2);
        jb.addActionListener(this);
    }
    public static void main(String arg[])
    {
        new Swingui();
    }

    public void actionPerformed(ActionEvent ae){
        try 
        {
            Class.forName("com.mysql.cj.jdbc.Driver");
            String url="jdbc:mysql://localhost/product";
            Connection con=DriverManager.getConnection(url,"root","");
            /*error*/Statement stmt=con.createStatement();
            String qry="select price from price where good='"+jtf1.getText().toString()+"'";
            /*error*/ResultSet resultSet= stmt.executeQuery(qry);
            int price = resultSet.getInt("price");
            JLabel jl3=new JLabel();
            String str;
            str=String.valueOf(price);
            jl3.setText(str);
            jl3.setBounds(50,300,100,50);
            jf.add(jl3);
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
}

MySQL database details are:

         database: product
         table : price
         columns are 
         good      price
         ==============
         gold10gm   35000
         dollar       78

Answer 1

Add the localhost port number in the URL. The resultSet maintains a cursor to the current row of data fetched. And initially, the cursor will be pointing before the current row and so you cannot directly fetch the results from the result set. Try iterating it before accessing the values.

ResultSet rs = stmt.executeQuery(query);
while(rs.next())
    rs.getInt("price");

Answer 2

   String qry="select * from price where good= ? ";
   PreparedStatement stmt=con.prepareStatement(qry);
   stmt.SetString(jtf1.getText().toString);
   stmt.execute();
   
   ResultSet resultSet= stmt.getResultSet();
   while (resultSet.next()) {
     int price = resultSet.getInt("price");
   }

   JLabel jl3=new JLabel();
   String str;
   str=Integer.toString(price);
   jl3.setText(str);
   stmt.close(); // close the prepare statement if you don't need it further