JAVA Applet Introduction
- JAVA Applet is another special java program where the user is communicating with HTML(Hyper Text Markup Language).
- An applet is nothing but a java byte code which is embedded in a HTML page, that means applet=java byte code + HTML page.
- That means to create an applet, we have to write a java program and compile it to get byte code(.class file).Then we will include it into HTML page in a particular location. Then this page is stored in the web server.
- A client machine communicates with the web server, the server then sends HTML page that contains applet. The page is then transmitted to the client where the applet is executed on the client's web browser.
- To create an applet, we need to import java.applet package and JApplet class of javax.swing package.
- Applets are used on internet for creating dynamic web pages.
- Applets are used for creating animations and games where the images can be displayed or moved.
There are some important differences between an applet and a standalone Java application, including the following:
- An applet is a Java class that extends the java.applet.Applet class.
- A main() method is not invoked on an applet, and an applet class will not define main().
- Applets are designed to be embedded within an HTML page.
- When a user views an HTML page that contains an applet, the code for the applet is downloaded to the user's machine.
- A JVM is required to view an applet. The JVM can be either a plug-in of the Web browser or a separate runtime environment.
- The JVM on the user's machine creates an instance of the applet class and invokes various methods during the applet's lifetime.
- Applets have strict security rules that are enforced by the Web browser. The security of an applet is often referred to as sandbox security, comparing the applet to a child playing in a sandbox with various rules that must be followed.
- Other classes that the applet needs can be downloaded in a single Java Archive (JAR) file.