Error when getting values from the JTable

Question

I coded for getting values from the JTable and get that value for do calculations.

//getting user input for selling qty 
        String Qty=JOptionPane.showInputDialog("Insert Selling Quantity :");
        double sellingqty=Double.parseDouble(Qty);

      //getting user input for specific item discount
        String discount = JOptionPane.showInputDialog("Insert Item Discount");
        double idiscount=Double.parseDouble(discount);

for(j=0;j<100;j++){
           double icost =(double) tableSale.getModel().getValueAt(j,2); 
        System.out.print(icost);

      //calculating Gross Total  
        double grosstotal = (sellingqty*icost)-idiscount;

        System.out.println(grosstotal);

        for(i=0;i<100;i++){
         //setting qty input value to table sale  
        tableSale.getModel().setValueAt(sellingqty,i, 3);
        //setting input value to table sale  
        tableSale.getModel().setValueAt(idiscount,i, 4); 
        //setting grosstotal value to table sale
        tableSale.getModel().setValueAt(grosstotal,i, 5); 
        }

       }

When I execute the code shows a null pointer exception.

java.lang.NullPointerException at 
com.bit.project.Newsale.add_btnActionPerformed(Newsale.java: 710) at 
com.bit.project.Newsale.access$800(Newsale.java: 37) at 
com.bit.project.Newsale$12.actionPerformed(Newsale.java: 469) at 
javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java: 2022) at 
javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java: 2022) at 
javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java: 2346)

This line shows the Null Pointer Exception

 double icost =(double) tableSale.getModel().getValueAt(j,3);

What is the error here?

So either tableSale is null, of the value returned by tableSale.getModel() is null. Use your debugger to find out, or just add traces in the code. — JB Nizet, Jul 26 '15 at 11:55
@tenten are you sure that `tableSale.getModel()` is not null? — Karthik, Jul 26 '15 at 11:55
@FastSnail currently no rows.. I coded to add specific row, when click of a button. above code executes after adding the row. — tenten, Jul 26 '15 at 11:57
@tenten as JB Nizet said, you should put a debug point at line 710, and check what is null in that line. — Karthik, Jul 26 '15 at 11:59

Error when getting values from the JTable

0 Answers0