私は2つのJComboBoxを使用しています
String arr1[] = {"text1", "text2", "text3"};
String arr2[] = {"text1", "text2", "text3"};
JComboBox box1 = new JComboBox(arr1);
JComboBox box2 = new JComboBox(arr2);
次のような条件を探している場所
if(text1 in box1 is selected)
only text2 and text3 is selectable/enabled in box2