Java Reference
In-Depth Information
Let's take a close look at the new things in this program. First, notice that the program
now imports both the
java.awt
and
java.awt.event
packages. The
java.awt
package is
needed because it contains the
FlowLayout
class, which supports the flow layout manager.
The
java.awt.event
package is needed because it defines the
ActionListener
interface and
the
ActionEvent
class.
Next, the class
ButtonDemo
is declared. Notice that it implements
ActionListener
. This
means that
ButtonDemo
objects can be used to receive action events. Next, a
JLabel
ref-
erence is declared. This reference will be used within the
actionPerformed( )
method to
display which button has been pressed.
The
ButtonDemo
constructor begins by creating a
JFrame
called
jfrm
. It then sets the
layout manager for the content pane of
jfrm
to
FlowLayout
, as shown here:
