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An anonymous class that extends an existing class

The program illustrates the use of an anonymous class that extends the WindowAdapter class, to instantiate an object to handle window events fired by the close button in theupper-right corner of the Frame object shown in Figure 2 . This class also uses the source-listener event model, and uses an instance initializer todisplay the name of the class file.

The screen output

The program produces the screen output shown in Figure 4 when

  • The program is started
  • Each button shown in Figure 2 is clicked once in succession, going from left to right
  • The close button in the upper-right corner of the Frame object in Figure 2 is clicked

When the close button is clicked, the program produces the last line of text in Figure 4 and terminates. I will identify the code that produces each line of output text in the discussion of the program that follows.

The controlling class

The controlling class for the program is shown in Listing 1 .

As you can see, the controlling class is very simple, with the main method instantiating an object of the GUI class. This results in the GUI that is pictured in Figure 2 .

Local and anonymous classes inside GUI constructor

The local class and the three anonymous classes are defined inside the constructor for the GUI class.

(Recall that local classes and anonymous classes are defined inside code blocks, which often place them inside methods and constructors, but you canalso place them inside static initializer blocks and instance initializers.)

The first four lines of the output text in Figure 4 are produced by constructors and instance initializers in the local and anonymous classes.Therefore, those four lines of text are produced when the new object of the GUI class is instantiated.

The GUI class

As is often the case, the GUI class used to create the visual GUI shown in Figure 2 consists solely of a constructor. Basically, this constructor

  • places three buttons in the frame and
  • registers event handlers on the buttons and on the frame.

Once the GUI object is constructed and appears on the screen, all furtheractivity in the program occurs under control of the event handlers associated with the buttons and the frame.

(You can learn more about event handling here .)

The GUI constructor

The GUI class, and the constructor for that class begin in Listing 2 .

As you can see, the GUI class extends Frame , so that an object of the class is a frame.

The constructor code shown in Listing 2 simply sets values for the layout, size, and title properties of the frame.

The BaldButton class

The definition of the BaldButton class begins in Listing 3 . This is a local class that extends Button .

Extending the Button class makes it possible to override the processMouseEvent method in order to handle mouse events that are fired by the button.

This is a form of low-level event handling that will be contrasted with source-listenerevent handling later in the program.

Listing 3 shows the constructor for the BaldButton class.

Enable mouse events

The most important code in the constructor is the statement that enables mouse events on the button.

Questions & Answers

what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
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