Java's Advanced User Interface Components (
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Last time, we mastered some basic UI components and worked on how to add them to panels, organize their layout, and manage their events. Having covered all the basic techniques that we’ll need to get started with Java interface programming in our first article, Java's Basic User Interface Components, we will move on to some advanced UI components. Today, I’ll be covering scrolling lists, scrollbars, and canvases, and their functionality. It is amazing to see how many of complex tasks are simplified with the help of these advanced user interface components.Last time, we mastered some basic UI components and worked on how to add them to
panels, organize their layout, and manage their events. Having covered all the
basic techniques that we’ll need to get started with Java interface programming
in our first article, Java's Basic User Interface Components, we will move on to
some advanced UI components. Today, I’ll be covering scrolling lists,
scrollbars, and canvases, and their functionality. It is amazing to see how many
of complex tasks are simplified with the help of these advanced user interface
components.
The List Class The list class allows us to
create a scrolling list of values. We can enable single or multiple selections
using a list. All that the user has to do is double-click on an item to make a
selection. A scrolling list is functionally similar to a choice menu in that it
lets us pick several options from a list, but scrolling lists differ in two
significant ways:
- Scrolling lists are not pop-up menus. They're displayed as a list of items
from which you can choose one or more items. If the number of items is larger
than the list box, a scrollbar is automatically provided so that you can see the
other items.
- You can choose more than one item in the list (if the list has been defined
to allow multiple selection).
In short, scrolling lists provide a
menu of items that can be selected or deselected. Unlike choice menus, scrolling
lists are not pop-up menus and can be defined to allow multiple selections. To
create a scrolling list, an instance of the
List class is created and
then we add individual items to that list.
To create a scrolling list
use, one of the following constructors:
- List() creates an empty scrolling list that enables only one
selection at a time.
- List(int, boolean) creates a scrolling list with the indicated
number of items visible on the list (there is no limit as to the number of
actual items you can add to the list). The boolean argument indicates whether
this list enables multiple selections (true) or not (false).
After creating a
List object, add items to it using the
addItem() method and then add the list itself to the panel that
contains it. Here's an example that creates a list five items high that allows
multiple selections
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