Mysql - access denied + “Too many connections”

Question

I have just started developing Java application and using MySQL. The application was working before, but basically after I restarted the computer, it stopped working saying "Too many connection".

I know I have done something wrong when I was closing the connection, but I can't figured it out. If you can please point me where I am doing wrong, please.

    public class ProductFrame extends javax.swing.JFrame {

    /**
     * Creates new form ProductFrame
     */
    public ProductFrame() {
        initComponents();
        Show_Products_In_JTable();


    }

    public Connection getConnection()
    {

        Connection con = null;
        try {
            con = DriverManager.getConnection("jdbc:mysql://localhost/smart-mart","root","");
            return con;
        } catch (SQLException ex) {
            Logger.getLogger(ProductFrame.class.getName()).log(Level.SEVERE, null, ex);
            return null;
        }

    }




        public boolean checkInputs()
    {
        if(
              txt_name.getText() == null
           || txt_price.getText() == null
           || txt_quantity.getText() == null
            || txt_arrdate.getText() == null
            || txt_minreq.getText() == null
            || txt_maxreq.getText() == null    
                || txt_staff.getText() == null

          ){
            return false;
        }
        else{
            try{
                Float.parseFloat(txt_price.getText());
                return true;
            }catch(Exception ex)
            {
                return false;
            }
        }
    }

   //** Display Date in the ItemTable ** //
        //** Step 1- Create an arraylist and fill it with date **//

        public ArrayList<Product> getProductList ()
        {
            ArrayList<Product> productList  = new ArrayList<Product>();
            Connection con = getConnection();
            String query = "SELECT * FROM product";

            Statement st;
            ResultSet rs;

        try {
            st = con.createStatement();
             rs = st.executeQuery(query);
              Product product;


   Show_Products_In_JTable();



              while (rs.next())
              {
                  product  = new Product (rs.getInt("id"),rs.getString("name"), Float.parseFloat(rs.getString("price")),rs.getInt("quantity"), rs.getString("arrdate"), rs.getInt("minreq"),rs.getInt("maxreq"), rs.getString("staff"));
                  productList.add(product);
                  con.close();
              }
        } catch (SQLException ex) {
            Logger.getLogger(ProductFrame.class.getName()).log(Level.SEVERE, null, ex);

        }
        return  productList;
        }






        //** Stept 2- Populate the table ** //



    public void Show_Products_In_JTable()
    {
        ArrayList<Product> list = getProductList();
        DefaultTableModel model = (DefaultTableModel) J_Table_Products.getModel();






        Object[] row = new Object [8];
        for(int i = 0; i<list.size();i++)
        {
        row[0]=list.get(i).getId();
        row[1]=list.get(i).getName();
        row[2]=list.get(i).getPrice();
        row[3]=list.get(i).getQuantity();
        row[4]=list.get(i).getArrDate();
        row[5]=list.get(i).getMinReq();
        row[6]=list.get(i).getMaxReq();
        row[7]=list.get(i).getStaff();

        model.addRow(row);


    }
    }

  // Show Data In Inputs
    public void ShowItem(int index)
    {
            txt_id.setText(Integer.toString(getProductList().get(index).getId()));
            txt_name.setText(getProductList().get(index).getName());
            txt_price.setText(Float.toString(getProductList().get(index).getPrice()));
            txt_quantity.setText(Integer.toString(getProductList().get(index).getQuantity()));
            txt_arrdate.setText(getProductList().get(index).getArrDate());
            txt_minreq.setText(Integer.toString(getProductList().get(index).getMinReq()));
            txt_maxreq.setText(Integer.toString(getProductList().get(index).getMaxReq()));
            txt_staff.setText(getProductList().get(index).getStaff());
    }       

    private void btn_insertActionPerformed(java.awt.event.ActionEvent evt) {                                           
      if (checkInputs() && txt_name !=null){

          try {
           Connection con = getConnection();
          PreparedStatement ps;
              ps = con.prepareStatement("INSERT INTO product(name, price, quantity, arrdate, minreq, maxreq, staff)"+"values(?,?,?,?,?,?,?)");
               ps.setString(1, txt_name.getText());
                ps.setString(2, txt_price.getText());
                ps.setString(3, txt_quantity.getText());
                ps.setString(4, txt_arrdate.getText());
                ps.setString(5 , txt_minreq.getText());
                ps.setString(6 , txt_maxreq.getText());
                ps.setString(7, txt_staff.getText());




                ps.executeUpdate();

                Show_Products_In_JTable();
                JOptionPane.showMessageDialog(null, "Data Inserted");

                ps.close();
          } catch (SQLException ex) {
              JOptionPane.showMessageDialog(null, ex.getMessage());
          }

      }
      else{
          JOptionPane.showMessageDialog(null, "One or more field empty");
      }


          System.out.println("Name=>" + txt_name.getText());
          System.out.println("Price=>" + txt_price.getText());
          System.out.println("Quantity=>" + txt_quantity.getText());
          System.out.println("Arrdate=>" + txt_arrdate.getText());
          System.out.println("MinReq=>" + txt_minreq.getText());
          System.out.println("MaxReq=>" + txt_maxreq.getText());
           System.out.println("Staff=>" + txt_staff.getText());



    }                                          

    private void btn_updateActionPerformed(java.awt.event.ActionEvent evt) {                                           
if (checkInputs() && txt_id.getText () !=null)
{
       String UpdateQuery = null;
    PreparedStatement ps = null;
    Connection con = getConnection ();

    try {


    UpdateQuery = "UPDATE product SET name=?, price=?,quantity=?, arrdate=?, minreq=?,maxreq=?, staff=? WHERE id=?";
    ps = con.prepareStatement(UpdateQuery);
                   ps.setString(1, txt_name.getText());
                ps.setString(2, txt_price.getText());
                ps.setString(3, txt_quantity.getText());
                ps.setString(4, txt_arrdate.getText());
                ps.setString(5 , txt_minreq.getText());
                ps.setString(6 , txt_maxreq.getText());
                ps.setString(7, txt_staff.getText());
                ps.setInt(8, Integer.parseInt(txt_id.getText()));


        ps.executeUpdate();
        ps.close();
    } catch (SQLException ex) {
        Logger.getLogger(ProductFrame.class.getName()).log(Level.SEVERE, null, ex);
    }
}else{
    JOptionPane.showMessageDialog(null, "One or more fields are Empty");
}
    }                                          

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

        if (!txt_id.getText().equals(""))

        {

            try {
                Connection con = getConnection();
                PreparedStatement ps = con.prepareStatement("DELETE FROM product WHERE id = ?");
                int id = Integer.parseInt(txt_id.getText());
                ps.setInt(1, id);
                ps.executeUpdate();


                JOptionPane.showMessageDialog(null, "Item Deleted!");
                ps.close();
            } catch (SQLException ex) {
                Logger.getLogger(ProductFrame.class.getName()).log(Level.SEVERE, null, ex);
                JOptionPane.showMessageDialog(null, "Item Not Deleted!");
                 ex.printStackTrace();

                    } finally {

}

        }
        else{
            JOptionPane.showMessageDialog(null, " Product not found. Please enter the product ID!");
        }

    }                                          

    private void J_Table_ProductsMouseClicked(java.awt.event.MouseEvent evt) {                                              
        int index = J_Table_Products.getSelectedRow();
        ShowItem(index);
    }                                             




    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(ProductFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(ProductFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(ProductFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(ProductFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new ProductFrame().setVisible(true);
            }
        });
    }

C.

Answer 1

You are creating a new connection each time that you are you invoking the method getConnection but you don't close it and lose the reference each time that the program is getting out of the function context, so the connection will be opened until the program is running. This situation provokes this issue ( too many connections ).

Close the connection one you have used it, or keep a reference to just one opened connection to to reuse it and avoid the process of Open-Use-Close.