Question

I don’t know if I can explain this and post the proper code to make it clear, but I will try.
I have five classes. They are being used to check the validity of an ISBN number. I am getting the error “cannot find symbol – method getISBN(). I have a gui object which I have instantiated. The error comes from the Handler, here:

       public void actionPerformed(ActionEvent e)
   {
       if (e.getSource()==gui.validateButton)
       {
          try
          {
            gui.ISBNText.getISBN();/////////////error//////////
            gui.status.setText("ISBN " + ISBNText.bookNum + " is valid");
          }
          catch(ISBNException er)
          {
            gui.status.setText(er.getMessage());    
          }
       }
      else System.exit(0);

I wont post any code from the gui, you get the idea: theres a gui, it has a textfield called ISBNText, and in the ISBNText class, there is a method to retrieve my text, called getISBN, code:

    public ISBNText() 
{
    super(20);
}  
//retrieve the ISBN num from textfield
public String getISBN() throws ISBNException
{           
    bookNum = getText();    
    validateISBN(bookNum);
    return bookNum;      
}

I hope this is enough, but not too much, to go on. Any ideas?

Answer 1

Without seeing the GUI class, it’s difficult to say. But I would suspect that your ISBNText field is declared as is :

JTextField ISBNText = new ISBNText();

If that’s the case, then getISBN() can’t be found because the variable’s declared type is JTextField, and not ISBNText. You need to change it to

ISBNText ISBNText = new ISBNText();

Note that public variables should almost never be used, and that variables in Java should always start with a lower-case letter. You should thus call it isbnText rather than ISBNText.