CODEWITHSUNDEEP
javastringswingjtableclasscastexception
Vsal
Vsal

Reputation: 83

how to solve java.lang.ClassCastException error

I have designed default table model in JTable properties of swing eclipse. so when i tried to do calculations get error......Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer 

public class punchingPBill extends JFrame
{
    DefaultTableModel model;
    Double rate,discount,amount,exciseduty,outputvat;

    {
        String[] columnNames =  {"Sr.No", "Description Of Goods", "quantity", "Rate", "Per", "Discount", "Basic Excise Duty", "Output Vat", "Amount"};
        Object[][] data = { {new Integer(1),"",new Integer(1), new Double(0.0),new Double(0.0),new Double(0.0),new Double(0.0),new Double(0.0),new Double(0.0)}};

    model = new DefaultTableModel(data, columnNames);
    }       
        table.setModel(model);
        table.setRowHeight(25);

private void setTableModelListener()
    {
        System.out.println("enter listen");
        TableModelListener tableModelListener = new TableModelListener() 
{
         public void tableChanged(TableModelEvent e)
            {
               if (e.getType() == TableModelEvent.UPDATE)
                {
                    System.out.println("Cell " + e.getFirstRow() + ", "
                            + e.getColumn() + " changed. The new value: "
                            + table.getModel().getValueAt(e.getFirstRow(),
                                    e.getColumn()));
                    int row = e.getFirstRow();
                    int column = e.getColumn();

                    if(column == 2||column == 3||column == 5)
                    {
                     Integer    quantity = ((Integer) model.getValueAt(row, 2)).intValue();
                   rate = ((Double) model.getValueAt(row, 3)).doubleValue(); 
                   discount=((Double) model.getValueAt(row, 5)).doubleValue();
                   amount=new Double(rate-(quantity*rate*(discount/100)));

                   model.setValueAt(amount, row, 8);

                 }

                }
            }
        };
        table.getModel().addTableModelListener(tableModelListener);
}

got errors at- Integer quantity = ((Integer) model.getValueAt(row, 2)).intValue();.......rate = ((Double) model.getValueAt(row, 3)).doubleValue();......discount=((Double) model.getValueAt(row, 5)).doubleValue();

Upvotes: 1

Views: 10237

Answers (3)

AxelH
AxelH

Reputation: 14572

You forgot to tell that this happened when you change the value.

Since you are editing the value, it use an JTextComponent (A JTextField most likely) to get the value (the cell showing a cursor), so the result is coming for JTextComponent.getText() as a String, not an Integer. So you need to parse the value with :

Integer.parseInt(string)

Of course, this will throw an exception if you input a not integer value.

EDIT : You can see the type changement if you print the class of it :

System.out.println(model.getValueAt(row, 2));
System.out.println(model.getValueAt(row, 2).getClass());

Before you update it, it will output

1
Integer

After you input anything (let say 2)

2
String

Here is one way to be sure this will work before and after and edit : (with correct format input, won't work if you input alphabetic value)

if (column == 2 || column == 3 || column == 5) {
    Integer quantity = Integer.parseInt(model.getValueAt(row, 2).toString());
    rate = Double.parseDouble(model.getValueAt(row, 3).toString());
    discount = Double.parseDouble(model.getValueAt(row, 5).toString());
    amount = new Double(rate - (quantity * rate * (discount / 100)));

    model.setValueAt(amount, row, 8);
}

The solution would be to manage the editing to parse the value directly but this would ask more code

Upvotes: 1

Neeraj Jain
Neeraj Jain

Reputation: 7730

I am assuming below line is throwing this exception:

Integer    quantity = ((Integer) model.getValueAt(row, 2)).intValue();

Try debugging what is getting returned from model.getValueAt(row, 2), if it returns String then you need to use:

Integer.parseInt(returnedValueFromMethodCall);

Upvotes: 1

Jeet
Jeet

Reputation: 248

You can use Integer.parseInt("StringValue") in place of casting where "StringValue" should be a proper number value which can be converted to Integer

Upvotes: 1

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