Forem: Ashwin vijay

what are primitive data types in java?

Ashwin vijay — Wed, 18 Feb 2026 05:22:29 +0000

Types of data

1. byte
size:1 byte
Default value:0
Description:Small integer(-128 to 127)
Eg:byte b=100;
2. short

size:2 bytes
Default value:0
Description:Medium integer(-32768 to 32,767)
Eg:short s=10000;
3. int
size:4 bytes
Default value:0
Description:Standard integer(-2^31 to 2^31)
Eg:int i=100000;
4. long
size:8 bytes
Default value:0L
Description:Large integer(-2^63 to 2^63)
eg:long l=10000000000L

5. float
size:4 bytes
Default value:0.0f
Description:Decimal number(single precision)(−3.4×10^38 to + 3.4×10^38)
eg:float f=5.75f
6. double
size:8 bytes
Default value:0.0d
Description:Decimal number (double precision)(−1.8*10^308 to 1.8*10^308)
Eg:double d=19.99
7. char
size:2 bytes
Default value:'\u0000'
Description:Single Unicode character
Eg:char c='A'
8. boolean
size:1 bytes
Default value:false
Description:True or False
Eg:boolean flag=true

what are data types in Java?

Ashwin vijay — Mon, 09 Feb 2026 04:54:29 +0000

A data type specifies the type of data a variable can store.

Java has two main categories
1)primitive Data types-basic building blocks.
2)Non-primitive Data Types(Reference Types)-objects,arrays,strings,etc

What is class?

Ashwin vijay — Sat, 07 Feb 2026 05:30:19 +0000

In Java, classes and objects form the foundation of Object-Oriented Programming (OOP). They help model real-world entities and organize code in a structured way.

A class is a blueprint used to create objects that share common properties and behavior.
An object is an instance of a class. It represents a specific entity created from the class template.
For Example, Dog is a class, Tommy is an object of that class.

Java class
A class is a blueprint that defines data and behavior for objects. It groups related fields and methods in a single unit. Memory for its members is allocated only when an object is created.

Acts as a template to create objects with shared structure.
Does not occupy memory for fields until instantiation
Can contain fields, methods, constructors, nested classes and interfaces.

what is JVM?

Ashwin vijay — Wed, 04 Feb 2026 04:34:57 +0000

JVM(Java Virtual Machine)

JVM is the heart of Java
Loads .class files
Verifies bytecode
Converts bytecode to machine code
Manages memory
Runs the program

what is JDK?

Ashwin vijay — Wed, 04 Feb 2026 04:17:38 +0000

JDK(Java development kit) which is used by developers to write programs contains

JRE(Java Runtime Environment).
Java C(compiler)
Debugger

-other dev tools

It’s a Java application and applet development environment. JRE, a compiler, an interpreter or loader, and a number of development tools are all included in the Java Development Kit. Now we will walk through these development tools which come along with JDK:

Java(loader/executor): responsible for launching Java applications
javac(compiler): It is responsible for compilation of java programs
Javadoc: provides support for generation of API documentation
Jar: responsible for creating and managing all JAR files.

Difference between null and undefined?

Ashwin vijay — Tue, 03 Feb 2026 05:19:34 +0000

Undefined

undefined is a primitive value automatically assigned to the variable in certain situations like

Difference ==(Loose Equality) and ===(Strict Equality)?

Ashwin vijay — Fri, 21 Nov 2025 07:10:07 +0000

==(Loose Equality)

Compares value only.
Does type coercion if the types are different. eg:console.log(5=='5') it will return true.it will convert the string to number
It is converted to number instead of string because number as it is simple eg: console.log(0==false) in this line false boolean type is converted to 0 and finally 0==0 which it will return true.

===(Tight Equality)

Compares both value and type
It will not do type coercion , eg:console.log(5==='5').it will return false console.log(0==false).will return false.

What is scripting language?

Ashwin vijay — Thu, 30 Oct 2025 15:37:55 +0000

A scripting language is an interpreted programming language meaning its code is executed line by line by ab interpreter(like Python,JavaScript,Bash),rather than being compiled into machine code first (like C or Java).

Main Purpose

To automate repetitive tasks
To Control or connect other software
To add interactivity to web pages or application
It is interpreted by browser or Node.js

What is JavaScript?

Ashwin vijay — Thu, 30 Oct 2025 15:15:07 +0000

JavaScript(high-level,interpreted programming language) is the programming language for web.
It can update and change both HTML and CSS.
It can change and manipulate data.

What is HTML?

Ashwin vijay — Sun, 28 Sep 2025 15:37:25 +0000

HTML(Hyper Text Mark Up Language) is most building block of the web.It defines the meaning and structure of the web content.HTML with other technologies are used to create presentation of web page and functionality of web page.
Eg: HTML skeleton

<html>
     <head>
     </head>
        <body>
           content
        </body>

   </html>

HI,from now onwards i'm interested to learn with this dev community.

Ashwin vijay — Thu, 18 Sep 2025 18:06:00 +0000