As you may have guessed, the object that represents the application is an instance of the ClickMeApp class, the object that represents the custom component is an instance of ClickMe, and the spot is represented by an instance of Spot. Because the object that represents the spot on the screen is very simple, let's look at its code. The Spot class declares three instance variables: size contains the spot's radius, x contains the spot's current horizontal location, and y contains the spot's current vertical location. It also declares two methods and a constructor — a subroutine used to initialize new objects created from the class.

To develop java applications you need to set-up the Java platform. Followings are required:
• Java Development Kit (JDK),it’s a java development,running (deployment) environment and includes:
1. Java Runtime Environment (JRE),that contains Java Virtual Machine and base APIs such as about I/O,RMI…etc.
2. Development tools & APIs such as the Java compiler and Java launcher tools
You can refer to the site from Sun Microsystems below to download JDK installation package

After you compile and update your generated Java code in your Java Editor, you may reverse engineer the code into a class diagram. Select Utilities - Preferences to select Java. Select Utilities - Reverse Directory. Select the Java files to be reversed. Select OK. With Class reads the Java files and creates the class diagram. You may reverse any Java code that successfully compiles. Below is the reversed class diagram from the Car Transportation System. This diagram shows the Unified Method graphic symbols. The trailing $, e.g. Car$, indicate an overloaded function name

The steps below are to install the JDK version for Microsoft Windows OS:
• Run the executable file of the downloaded installation package. The name of this file under format JDK-version-windows-chipset_type.exe
• Select all features as below:

The ClickMe component responds to mouse clicks by displaying a spot at the click location. Any object can detect mouse clicks on a component. It just needs to implement the MouseListener interface and register with the component as a mouse listener. The MouseListener interface declares five methods, each of which is called for a different kind of mouse event: when the mouse is clicked, when the mouse moves outside of the component, and so on. Even though the ClickMe component responds only to mouse clicks, its mouse listener implementation must have all five methods. The methods for the events that the object isn't interested in are empty