title: JCombobox string item (visible) and integer key (inherent)
body: <p>I have a database schema =  which will be shown in a JCombobox as a JTable column to select a name. But I want the ID field to insert (as a foreign key) in another table. </p>
  
  <p>Usually, selecting an Item in drop down, bring the selected item to the shown area of the combo box. </p>
  
  <p>What I want to do is, when select any item (string) in the combo box its corresponding integer key (can be kept in  a sorted map) should be shown in the combobox placeholder area, so that when take the value of the JTable.getValueAt(row, column), I get the integer key, not the string item value. 
  Please help me how can I do that?</p>