Java

 Public class Hello world{

public static void main(String

Technical note:

What is .bat or .sh files? 

A .bat file is a windows batch file it contains a sequence of windows/dos commands. These cannot be used in a Unix shell prompt.

A .sh file is a unix shell script it contains a series of unix commands. These cannot be ran in a Windows DOS or Powershell prompt.

How to create .bat or .sh file? 

You just need to create the file, similar to the way we created a Java file, and set the proper extension: either .bat or .sh depending on the Operating system of your computer.

How to edit .bat or .sh file? 

You can edit these files in the simple text editor. So, you can make the mouse right-click on the file, and select "open with notepad" and edit it in the notepad.

What is IDE

Integrated Development Environment is a software application that provides comprehensive facilities to computer programmers for software development.

Consists of a source code editor, build automation, tools, debugger, and compiler.

Most popular IDE for java development 

Eclipse 

completely free 

standard IDE  in the majority of companies

it has a huge community 

A lot of free extensions and plugins

It has free tools for EE development (JSP syntax, support, sprint support)

Intelijidea

NetBeans 

Android Studio 

what is IDE 

Java comments 

The java comments are statements that are not executed by JVM 

Used to make code maintenance easier 

Can provide information about a specific pieces of code 

can be used todo 

DEMO

Primitive types and variables 

what data types exist in java?

Data types 

Primitive types

 integers 

floating point number 

booleans

Characters

Reference Types 

Classes 

Annotations 

Interfaces 

Enumerations 

Arrays

Java is a strongly typed language 

Every language has a type 

Every expression has a type

Each type is strictly defined 

Variable 

a piece of memory, each variable has a type, is defined by the combination of identifier and a type, you can declare the variable with "var" 

 Number Systems 

Data types 

Decimal base 10  (0,1,2,3,4,5,6,7,8,9)

Binary Base 2 (0,1)

Octal Base value 8 (0,1,2,3,4,5,6,7,)

Hexadecimal Base value 16 (1,2,3,4,5,6,7,8,9A,B,C,D,E,F)

Binary Number System 

Radix is 2 

0,1

1 0 1 1

Arrays overview 

An array is an object which contains elements of similar data types and supports access to them by index 

index of the first element in Array is 0 

No dynamic size 

can't change