JavaFX 2.0 :: Combobox Inside A Tablecell

I have a combo box inside a table cell for each row. I have defined a value change listener for each combobox. Whenever the combo box value is changed, the selected item is placed inside a MAPVOBean. The problem i am facing is when the user scrolls Up and down the tableview , the change listener is fired even without clicking on it the explicitly, and this changes the my value in my data structure. How to handle this. The source code is attached.

My Model:

Person class

Has first name, last name and MAPVOBean.

Address is stored in a MAPVOBean. It has a map and key is house number and the value is the state where the house is. It is assumed that the person can have one house in each state.

Columns in table view:

Column 1: First Name
Column 2: Last name
Column 3: State combo box. This shows the state in which the person owns a house. 

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package taleviewtester;
import java.io.IOException;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;

[Code] .....