BeerShop Inventory Management System using Java

 DefaultTableModel m;
 int sum = 0;
 
        if(txtKing.isSelected())
        {
            String kingfish = "King Fisher";
            int  price = 200;
            int  qty = Integer.parseInt(txtKgQty.getText());
            int tot = price * qty;   
            m = (DefaultTableModel)jTable1.getModel();
            
            m.addRow(new Object[]          
            {
                kingfish,
                price,
                qty,
                tot 
            }        
             );    
        }
        
        if(txtHay.isSelected())
        {
            String Haywards = "Haywards";
            int  price = 100;
            int  qty = Integer.parseInt(txtHayQty.getText());
            int tot = price * qty;   
            m = (DefaultTableModel)jTable1.getModel();
            
            m.addRow(new Object[]          
            {
                Haywards,
                price,
                qty,
                tot 
            }        
             );    
        }
        
         if(txtRoyal.isSelected())
        {
            String Royal = "Royal Challenge";
            int  price = 300;
            int  qty = Integer.parseInt(txtRoyQty.getText());
            int tot = price * qty;   
            m = (DefaultTableModel)jTable1.getModel();
            
            m.addRow(new Object[]          
            {
                Royal,
                price,
                qty,
                tot 
            }        
             );    
        }
        
        if(Knock.isSelected())
        {
            String Knock = "Knock Out";
            int  price = 350;
            int  qty = Integer.parseInt(txtKnoQty.getText());
            int tot = price * qty;   
            m = (DefaultTableModel)jTable1.getModel();
            
            m.addRow(new Object[]          
            {
                Knock,
                price,
                qty,
                tot 
            }        
         );    
        }
        
        for(int i=0; i<jTable1.getRowCount(); i++)
        {
            sum = sum + Integer.parseInt(jTable1.getValueAt(i, 3).toString());  
        }
        
        txtPay.setText(Integer.toString(sum));

i have attached the video link below. which will do this tutorials step by step