Java notes

1. Java Programming
CH 1 Introduction

2. Introduction

5. • 1. Object Oriented:
• In Java, everything is an Object. Java can be easily extended
since it is based on the Object model.
• 2. Platform Independent
• Java is guaranteed to be write-once, run-anywhere
language.
• On compilation Java program is compiled into bytecode.
This bytecode is platform independent and can be run on
any machine, plus this bytecode format also provide
security. Any machine with Java Runtime Environment can
run Java Programs.
• 3.Strong-type Checking:
• Java is a strongly typed programming language because
every variable must be declared with a data type. A
variable cannot start off life without knowing the range of
values it can hold, and once it is declared, the data type of
the variable cannot change.

6. • 4. Compile and Interpret:
• Java has two step process in java. You compile the
program and then you execute the program.
• 5. Garbage Collector:
• Java provides automatic garbage collector. It
automatically finds unused objects and variables and
remove them from memory to free a memory space
for program execution.
• 6. Multithreading:
• Java multithreading feature makes it possible to write
program that can do many tasks simultaneously.
Benefit of multithreading is that it utilizes same
memory and other resources to execute multiple
threads at the same time, like While typing,
grammatical errors are checked along.

7. • 7.Secure:
• It is secure by default. Because there is no
pointer in java. There is no possibilities of
having any memory leaks or references leaks
from the application.
• 8. Robust:
• Provides a very great exception handling
framework out of the box which developer
can use and implement to build resilient
applications.

8. How a Java Program runs

9. Anatomy of Java

10. Flavors of Java
• 1. J2SE
– Java 2 Standard Edition- if we are designing java application
without using client-server architecture or without distributing
java application logic on multiple machines that is called a
standalone.
– 5% Application
• 2. J2EE
– Java 2 Enterprise Edition-if we are designing java application
using client-server architecture or distributing java application
logic on multiple machines that is called as enterprise
application.
– 95% Application
– Eg. E-commerce, e-business
• 3. J2ME
– Java 2 Micro Edition
– Micro programming
– Mobile based Applications (used for nokia phones)