在Java中检查NULL

Question

I am using a Bonded JComboBox. What I want to know is how do I check if that JComboBox has any items in it or not.

Thank you.

Answer 1

To test if the JComboxBox reference is null , you can compare it with null using the == operator. To test if the combo-box contains any items, you can use the instance method getItemCount , which returns the number of items it contains.

JComboxBox box = ...
boolean boxIsNull = (box == null); // answers the title of the question
boolean boxHasItems = (box.getItemCount() > 0);