Home

JAVA APPLET

List boxes are significantly different from Choice boxes, and not just in appearance. While a Choice box drops down when you activate it, a List occupies some fixed number of lines on a screen all the time and doesn’t change. In addition, a List allows multiple selection: if you click on more than one item the original item stays highlighted and you can select as many as you want. If you want to see the items in a list, you simply call getSelectedItems( ), which produces an array of String of the items that have been selected. To remove an item from a group you have to click it again.

A problem with a List is that the default action is double clicking, not single clicking. A single click adds or removes elements from the selected group and a double click calls action( ).

When you press the button it adds items to the top of the list (because of the second argument 0 to addItem( )). Adding elements to a List is more reasonable than the Choice box because users expect to scroll a list box (for one thing, it has a built-in scroll bar) but they don’t expect to have to figure out how to get a drop-down list to scroll, as in the previous example.

However, the only way for action( ) to be called is through a double-click. If you need to monitor other activities that the user is doing on your List (in particular, single clicks) you must take an alternative approach.

A sample code for making simple Lists