What do you get when you download JDK 1.2? You get the same kinds of things as you did with prior JDK releases--just a lot more of everything.
Although demos and C native methods are not described in this lesson, you can download JDK 1.2 and run the demos yourself to see them in action.
- Java Virtual Machine (JVM) and core Java API class libraries
- Core source code for the Java API libraries
- Developer and administrative tools
- Demos showing the new JDK 1.2 features
- C header files to extend the core platform with C native methods
Java Virtual MachineThe Java Virtual Machine (JVM) is a platform-independent abstract computing machine and execution environment. Programs written in the Java language using the Java API libraries execute in the JVM. With JDK 1.2, the JVM has a strong security architecture to prevent applets and applications from executing outside their secure environment or sandbox.
Java API LibrariesJava API libraries consist of the core libraries and standard extensions. The API libraries covered in The Java Tutorial comprise some of the core Java APIs and the Servlets standard extension.
Licensees are required to adopt all core platform packages. Licensees are individuals or companies who take the Java original equipment manufacturer (OEM) source code and merge it into a commercial product by adapting the platform-dependent portions of the licensed source code to their platform.
The core source code is provided for your information and use when using the JDK 1.2 API libraries to write Java programs. The source code is for reference only; it cannot be compiled because of licensing agreements.
Standard ExtensionsJava APIs that enable vertical solutions such as JavaMail or collaboration applications are available as standard extensions. Extensions are packages of Java classes (and any associated native code) that application developers can use to extend the functionality of the core platform.
Developer and Administrative ToolsWith JDK 1.2 you get a full array of software development and administration tools. New tools like keytool and jarsigner support the new JDK 1.2 security architecture, while other tools introduced in earlier JDK releases have been enhanced. Visit the JDK 1.2 Solaris Tools and Windows Tools pages for a full list of tools and descriptions.
Java Runtime EnvironmentThe Java Runtime Environment (JRE) consists of the Java Virtual Machine (JVM) core API libraries, and other supporting files. It is the runtime part of the JDK with no compiler, debugger, or tools. The JRE is the smallest set of executables and files that constitute the standard Java platform.
If you have the JDK, the JRE is included so you can run Java programs. If you do not have the JDK, you can download the JRE to bundle with applications that might run on systems that do not have the JDK or JRE already installed.
JRE 1.2 has the same security architecture as JDK 1.2.
Licensees can license the Java Application Environment (JAE), which is the JRE source code, to adapt the JRE to their product.