Java Notes 10 Sept

Page 1

Sun distinguishes between its Software Development Kit (SDK) and Runtime Environment (JRE) which is a subset of the SDK,

the primary distinction being that in the JRE the compiler is not present.

There were five primary goals in the creation of the Java language:

1. It should use the object-oriented programming methodology.

2. It should allow the same program to be executed on multiple operating systems.

3. It should contain built-in support for using computer networks.

4. It should be designed to execute code from remote sources securely.

5. It should be easy to use by selecting what was considered the good parts of other object-oriented languages.

Difference between JDK, JRE and JVM JVM

JVM (Java Virtual Machine) is an abstract machine.

A specification that provides runtime environment in which java bytecode can be executed.

JVMs are available for many hardware and software platforms.

JVM, JRE and JDK are platform dependent because configuration of each OS differs. But, Java is platform independent.

The JVM performs following main tasks:

Loads code

Verifies code

Executes code

Provides runtime environment