Java Reference
In-Depth Information
Othercomponentclassesalsodeclaretheirown
remove
x
Listener(
x
Listener)
methods.
ActionListener
declares a single method, but some listeners declare multiple
methods.Forexample,
WindowListener
declaressevenmethods.Becauseitcanbe
tedious to override each method wherever you need to implement the interface, AWT
alsoprovidestheconceptofan
adapter
,whichisaconvenienceclassthatimplements
a multimethod interface by providing an empty version of each method. For example,
the
java.awt.event
packageincludesa
WindowAdapter
class,whichyou'llsee
demonstrated shortly.
Demonstrating Components, Containers, Layout Managers, and
Events
Nowthatyou'velearnedsomebasicsofcomponents,containers,layoutmanagers,and
events(andeventlisteners),let'sfindouthowtocombinethemintoausefulAWT-based
GUI. I've created a simple temperature-conversion application that presents a GUI for
obtainingdegreeinput,displayingdegreeoutput,andtriggeringconversionstodegrees
Celsius/Fahrenheit.
Listing 7-1
presents the source code.
Listing 7-1
. A simple GUI consisting of two labels, two textfields, and two buttons
import java.awt.Button;
import java.awt.EventQueue;
import java.awt.Frame;
import java.awt.GridLayout;
import java.awt.Label;
import java.awt.Panel;
import java.awt.TextField;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
class TempVerter extends Frame
{
TempVerter()
