Applets java programs Example:
To minimize download time, applets can be delivered in the form of a jar file. In the case of this example, if all necessary classes are placed in the compressed archiveexample.jar, the following embedding code could be used instead:
<p>Here it is: <applet archive="example.jar" code="HelloWorld" height="40" width="200">
This is where HelloWorld.class runs.
</applet></p>
Applet inclusion is described in detail in Sun's official page about the APPLET tag.[31]
Advantages:
A Java applet can have any or all of the following advantages:[32]
- It is simple to make it work on FreeBSD, Linux, Microsoft Windows and OS X—that is, to make it cross platform. Applets are supported by most web browsers.
- The same applet can work on "all" installed versions of Java at the same time, rather than just the latest plug-in version only. However, if an applet requires a later version of the Java Runtime Environment (JRE) the client will be forced to wait during the large download.
- Most web browsers cache applets so they will be quick to load when returning to a web page. Applets also improve with use: after a first applet is run, the JVM is already running and starts quickly (the JVM will need to restart each time the browser starts afresh). It should be noted that JRE versions 1.5 and greater stop the JVM and restart it when the browser navigates from one HTML page containing an applet to another containing an applet.
- It can move the work from the server to the client, making a web solution more scalable with the number of users/clients.
- If a standalone program (like Google Earth) talks to a web server, that server normally needs to support all prior versions for users which have not kept their client software updated. In contrast, a properly configured browser loads (and caches) the latest applet version, so there is no need to support legacy versions.
- The applet naturally supports the changing user state, such as figure positions on the chessboard.
- Developers can develop and debug an applet directly simply by creating a main routine (either in the applet's class or in a separate class) and calling init() and start() on the applet, thus allowing for development in their favorite Java SE development environment. All one has to do after that is re-test the applet in the AppletViewer program or a web browser to ensure it conforms to security restrictions.
- An untrusted applet has no access to the local machine and can only access the server it came from. This makes such an applet much safer to run than a standalone executable that it could replace. However, a signed applet can have full access to the machine it is running on if the user agrees.
- Java applets are fast - and can even have similar performance to native installed software.
Disadvantages:
Java applets depend on a Java Runtime Environment (JRE), which is a reasonably complex and heavy-weight software package. It also normally requires a plug-in for the web browser. Some organizations only allow software installed by an administrator. As a result, some users can only view applets that are important enough to justify contacting the administrator to request installation of the JRE and plug-in.A Java applet may have any of the following disadvantages compared to other client-side web technologies:
- If an applet requires a newer JRE than available on the system, or a specific JRE, the user running it the first time will need to wait for the large JRE download to complete.
- Some browsers, notably mobile browsers on Apple iOS or Android, do not run Java applets at all.[33]
- Unlike the older
applettag, theobjecttag needs workarounds to write a cross-browser HTML document. - There is no standard to make the content of applets available to screen readers. Therefore, applets can harm the accessibility of a web site to users with special needs.
Sun has made considerable efforts to ensure compatibility is maintained between Java versions as they evolve, enforcing Java portability by law if required. Oracle seems to be continuing the same strategy.
2002 Sun vs Microsoft
Microsoft continued to ship its own unmodified Java virtual machine. Over the years it became extremely outdated yet still default for Internet Explorer. A later study revealed that applets of this time often contain their own classes that mirror Swing and other newer features in a limited way.[36] In 2002 Sun filed an antitrust lawsuit, claiming that Microsoft's attempts at illegal monopolization had harmed the Java platform. Sun demanded Microsoft distribute Sun's current, binary implementation of Java technology as part of Windows, distribute it as a recommended update for older Microsoft desktop operating systems and stop the distribution of Microsoft's Virtual Machine (as its licensing time, agreed in the prior lawsuit, had expired).[35] Microsoft paid $700 million for pending antitrust issues, another $900 million for patent issues and a $350 million royalty fee to use Sun's software in the future.[37][38]
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