Java applet

A Java applet is a small application which is written in Java and delivered to users in the form of bytecode. The user launches the Java applet from a web page, and the applet is then executed within a Java Virtual Machine (JVM) in a process separate from the web browser itself. A Java applet can appear in a frame of the web page, a new application window, Sun's AppletViewer, or a stand-alone tool for testing applets. Java applets were introduced in the first version of the Java language, which was released in 1995.

Java applets can be written in any programming language that compiles to Java bytecode. They are usually written in Java, but other languages such as Jython,JRuby,Pascal,Scala, or Eiffel (via SmartEiffel) may be used as well.

Java applets run at very fast speeds and, until 2011, they were many times faster than JavaScript. Unlike JavaScript, Java applets had access to 3D hardware acceleration, making them well-suited for non-trivial, computation-intensive visualizations. As browsers have gained support for hardware-accelerated graphics thanks to the canvas technology (or specifically WebGL in the case of 3D graphics), as well as just-in-time compiled JavaScript, the speed difference has become less noticeable.

Java package

A Java package is a technique for organizing Java classes into namespaces similar to the modules of Modula, providing modular programming in Java. Java packages can be stored in compressed files called JAR files, allowing classes to be downloaded faster as groups rather than individually. Programmers also typically use packages to organize classes belonging to the same category or providing similar functionality. A package provides a unique namespace for the types it contains. Classes in the same package can access each other's package-private and protected members.

Overview

In general, a package can contain the following kinds of types. A package allows a developer to group classes (and interfaces) together. These classes will all be related in some way – they might all have to do with a specific application or perform a specific set of tasks. The Java API is a collection of packages – for example, the javax.xml package. The javax.xml package and its subpackages contain classes to handle XML.