Question

I am trying to use a data key pair in a combobox that is filled from a database. To update records in the database.
I am able to fill the combobox with data from the database, however when I go to update a record with data from the combobox I receive an error stating the I have a null pointer if the select index of the combobox is blank.
I am trying to devise a way to check if the box is blank, so that if it is I don’t use it for the update.
I am thoroughly stumped on this.

Here is the code I have so far to check for null values and run the update if the values is not null. The updates work by themselves but when I try getting data from a combobox where I have to cast the datatype and nothing is selected I receive the error.

public Boolean checkStrNull(String strTest) {
    if (strTest == null) {
        return false;
    } else if (strTest.isEmpty()) {
        return false;
    } else if (strTest == "") {
        return false;
    } else {
        return true;
    }
}

public Boolean checkIntNull(int intTest) {
    if (intTest == 0) {
        return false;
    } else {
        return true;
    }
}

public void updateIntAnimal(Animal a, String strField, Integer intNew)
        throws SQLException {
    if (checkIntNull(intNew)) {
        a.updateIntField(strField, intNew);
    }
}

public void updateStrAnimal(Animal a, String strField, String strNew)
        throws SQLException {
    if (checkStrNull(strNew)) {
        a.updateStrField(strField, strNew);
    }
}

Answer 1

You can use the getSelectedIndex() method on the combobox to see if there is a selection:

[…] Returns -1 if there is no selected item or if the user specified an item which is not in the list.