java.lang.numberformatexception 解析字符串输入数据库时

Question

I'm relatively new to Java and am trying to make a POS system with a checkout. I want to input invoices into a database by taking the values from a checkout table.

I have a table (jTable2) in which each of the items in the cells are objects. I have tried casting it to a string, and upon that failing, I used the toString() method, but I keep getting the same error. Here is my code

if(c<=itemcounter){
    String sql="INSERT into invoices(InvoiceID, ClientID, ProductName, ProductAmt, UnitPrice, TotalProductPrice) values (?,?,?,?,?,?)";
    Connection conn=MySqlConnection();

    PreparedStatement pstmt=conn.prepareStatement(sql);

    pstmt.setInt(1, InvoiceID);
    pstmt.setInt(2, Integer.parseInt(cIDField.getText()));
    pstmt.setString(3, (String)jTable2.getValueAt(c, 1));
    pstmt.setInt(4, Integer.parseInt(jTable2.getValueAt(c, 3).toString())); //THIS IS THE LINE I NEED HELP WITH
    pstmt.setDouble(5, Double.parseDouble((String) jTable2.getValueAt(c, 2)));
    pstmt.setDouble(6, Double.parseDouble((String) jTable2.getValueAt(c, 4)));
    pstmt.executeUpdate();
}

java.lang.numberformatexception for input string "(string that is a parsed cell c, 4 of jTable2)"

I don't understand what I can do to fix it. I would appreciate any help. Thank you!

Answer 1

Look at the line: Integer.parseInt(jTable2.getValueAt(c, 3).toString())

It get's the value from a table and converts it to an int. Guess what happens when the value retrieved is not an int? That's right, you get a NumberFormatException.

Create a safe helper method like:

private int safeConvertToInt(String value) {
  try {
    return Integer.parseInt(value);
  }
  catch (NumberFormatException e) {
    System.out.println("Error: Could not convert |" + value + "| to int");
    return 0;
  }
}

How safeConvertToInt behaves depends upon your needs. The above logs the error and returns the value zero. You may well want different error handling.