Click on items in the list to select (highlight) them. Multiple selection mode allows multiple items to be selected at the same time.
Click on the list in the manner used on your system to bring up a Java pop-up menu (e.g., right mouse button click on Windows and Solaris, command key (i.e., "Apple" or "clover" key) and click on Macintosh), This will bring up an edit dialog with which you can delete selected items, replace selected items with the text typed into the text field, and insert or append new items typed into the text field. These operations work on all the selected items in the multiple selection mode case. The edit dialog floats on top but by default is modeless so you can go back and forth between the dialog and the list. You can optionally set the edit dialog to modal to force it to remain in control until dismissed by the user.
(NOTE: The Netscape Communicator and Microsoft Internet Explorer browsers both regard the modal flag as only applying to Java and not to the browser window, so true modal behavior does not occur. Applet viewers and standalone Java applications exhibit the correct behavior.)
(NOTE: Microsoft Internet Explorer also does not honor Java window activation calls properly with respect to the browser window, so the edit dialog can get hidden behind the browser window. Drag the edit dialog elsewhere on the screen to keep it visible and click on it to make it active. Explorer also has a bug so that pop-up click does not work on an already selected item. See "Installation & Compatibility" section.)
In the single selection mode list you can use the mouse to drag and reorder elements in the list. Click, drag, and release to move items. Dragging above or below the list will autoscroll the list in the desired direction.
Dragging of items is disabled in multiple selection mode. This is because the standard Java AWT List does not provide a way to determine the drag destination when multiple selections are enabled, even though highlighting is performed by the underlying system (see User Manual). Applications should switch to single selection mode for reordering and back to multiple selection mode to permit multiple selections.
(NOTE: Different platforms vary on what they do when you switch from multiple selection mode to single selection mode with multiple items selected. Some immediately deselect all but the most recently clicked, some single select on the next click, and some don't switch until you unclick all but one item.)
You may also wish to look at the source code for this applet.