alpha : testing in own organization
beta : testing in public
nightly build : daily build or nightly build is the practice of completing software build of the latest version of program on a daily basis.
JEE - Java Enterprise Edition (for enterprise level applications)
JSE - Java Standard Edition (for stand alone)
JME - Java Micro Edition (for mobiles)
History of Java
Benefits of Java and its features
- Simple and easy to learn.
- Java is almost fully OOP.
- Java is robust and secure.
- Architecture neutral and portable.
- Provides High Performance
How is Java platform independent?
The meaning of platform independent is that, the java source code can run on all operating systems.
A program is written in a language which is a human readable language. It may contain words, phrases etc which the machine does not understand. For the source code to be understood by the machine, it needs to be in a language understood by machines, typically a machine-level language.
So, here comes the role of a compiler. The compiler converts the high-level language (human language) into a format understood by the machines. Therefore, a compiler is a program that translates the source code for another program from a programming language into executable code.
This executable code may be a sequence of machine instructions that can be executed by the CPU directly, or it may be an intermediate representation that is interpreted by a virtual machine. This intermediate representation in Java is the Java Byte Code.
Step by step Execution of Java Program
- Whenever, a program is written in JAVA, the javac compiles it. The result of the JAVA compiler is the .class file or the bytecode and not the machine native code (unlike C compiler).
- The bytecode generated is a non-executable code and needs an interpreter to execute on a machine. This interpreter is the JVM and thus the Bytecode is executed by the JVM.
- And finally program runs to give the desired output.
Write once, run everytime.