Online Java tutorial

Introduction of Java

The language, initially called Oak. James Gosling initiated the Java language project in June 1991 for use in one of his many set-top box projects.

Java is an object-oriented language, and this is very similar to C++. Java Programming Language is simplified to eliminate language features that cause common programming errors. Java source code files are compiled into a format called bytecode, which can then be executed by a Java interpreter.

Java is slow in speed due to following reasons.

• Dynamic Linking Unlike C, linking is done at run-time , every time the program is run in Java.
• Run-time Interpreter The conversion of byte code into native machine code is done at run-time in Java which furthers slows down the speed

Points to remember

1. Java states Write Once, Run Anywhere
   This means java is platform independent language.
2. Java virtual machine (JVM) A Java virtual machine (JVM) is a virtual machine that can execute Java bytecode. It is the code execution component of the Java software platform
3. Java bytecode Java bytecode is an intermediate language which is typically compiled from Java, but it can also be compiled from other programming languages.
4. Java execution environment is termed the Java Runtime Environment, or JRE.
5. Programs intended to run on a JVM must be compiled into a standardized portable binary format, which typically comes in the form of .class files. A program may consist of many classes in different files. For easier distribution of large programs, multiple class files may be packaged together in a .jar file (short for Java archive).