Learn Java Programming in 24 Hours

Learn Java Programming in 24 Hours

Learn with Complete Bible

By Alex Nordeen

Copyright 2021- All Rights Reserved – Alex Nordeen,

ALL RIGHTS RESERVED. No part of this publication may be reproduced or transmitted in any form whatsoever, electronic, or mechanical, including photocopying, recording, or by any informational storage or retrieval system without express written, dated and signed permission from the author.

Table of Contents

Introduction:  

Chapter 1: Introduction 

What is Java Platform ?

Working of Java Virtual Machine(JVM) & its Architecture

How to install Java JDK 8 and Java 8 download

Creating Your First Java Program

Chapter 2: OOPS

Easily understand concept of Object Oriented Programming(OOP's)

What is Abstraction in OOPS ?

Learn Java Encapsulation in 10 Minutes

Java Inheritance & Polymorphism

Chapter 3 Data Type

Java Variables and Data Types

Objects and Classes in Java

Java Array

Java String Tutorial

How to Split a String in Java

How to convert a Java String to Integer?

Working with HashMap in Java

How to use Java Arraylist

Chapter 4 Must Know Stuff!

Java THIS Keyword

Java Command Line Arguments

Chapter 5 Java Inheritance 

Java Abstract Class and Methods

Concept of Inheritance Java and Java Polymorphism

Chapter 6 Memory

Java Stack and Heap

Java Static Methods and Variables

How Garbage Collection Works in Java?

Chapter 7 Conditional Loops

How to Loop/Iterate an array in Java

Java Switch Case Tutorial

Chapter 8 Exception Handling

Java Exception Handling

Guide to Java Exception Hierarchy

Create User Defined Exception in Java

How to use throws keyword in Java Exception

Chapter 9 Math

Java Math Class Tutorial

Chapter 10 Important Stuff

Multithreading in Java

How to use Date in Java

How to use Java Timer and Example

Chapter 1: Introduction

What is Java Platform ?

To understand JAVA programming language, we need to understand some basic concept of how a computer program can run a command and execute the action.

Java is a programming language as well as a Platform

How about recollecting some basic concept of computing?

What is PC?

A computer is an electronic device capable of performing computations, and we all know that it composed of a monitor, keyboard, mouse and memory to store information. But the most important component of the computer is a PROCESSOR. Which does all thinking of computer, but the question is how the computer does this thinking? How does it understand text, images, videos, etc.?

The computer is an electronic device, and it can only understand electronic signals or binary signals. For example, the 5-volt electronic signal may represent binary number 1 while 0 volts may represent binary number 0. So your PC is continuously bombarded with these signals. 

Eight bits of such signals are group together to interpret Text, numerical and symbols.

For example, the # symbol is identified by computer by 10101010. Similarly, the pattern for adding a function is represented by 10000011.

This is known as 8-bit computing. Current day processor is capable of decoding 64 bit time. But what is the relation of this concept with the programming language JAVA. Let understand these with an example.

Suppose if you want to tell the computer to add two number (1+2) which is represented by some binary numbers (10000011), how are you going to tell the computer? Yes, we going to use assembly language to get our code executed.

Assembly Language is the most elementary form of software development languages.

We are going to give the command to a computer in this format as shown below. Your code to add two numbers in this language would be in this order

Store number 1 at memory location say A

Store number 2 at memory location say B

Add contents of Location A & B

Store results

But how are we going to do this? Back in 1950's when computers were huge and consumed great deal of power, you would convert your assembly code into corresponding machine code to 1 and 0’s using mapping sheets. Later these code will be punched into the machine cards and feed to the computer. The computer will read these code and execute the program. These would be a long process then until ASSEMBLER came to help.

What are Assembler and Compiler?

With the advancement in technology i/o devices were invented you could directly type your program into the PC using a program called ASSEMBLER. It converts it into corresponding machine code (110001..) and feed to your processor. So coming back to our example addition of (1+2), the assembler will convert this code into machine code and give the output.

That apart, you will also have to make calls to create Operating System provided functions to display the output of the code.

But alone assembler is not involved in this whole process, it also requires the compiler to compile the long code into a small chunk of codes. With advancement in software development languages, this entire assembly code could shrink into just one line print f 1+2 A with the help of software called COMPILER. It is used to convert your c language code into assembly code, and the assembler converts it into corresponding machine code, and this machine code will be transmitted to the processor. The most common processor used in PC or Computers are Intel processor.

Though present day compilers come bundled with assembler can directly convert your higher language code into machine code.

Now, suppose Windows operating system is running on this Intel processor, a combination of Operating System plus the processor is called the PLATFORM. The most common platform in the world is the Windows and Intel called the Wintel Platform. The other popular platforms are AMD and Linux , Power PC, and Mac OS X.

Now, with a change in processor, the assembly instructions will also change. For example the

Add instruction in Intel may be called ADDITION for AMD

OR Math ADD for Power PC

And obviously with a change in Operating System, the level and nature of O.S level calls will also change.

As a developer, I want my software program to work on all platforms available, to maximize my revenues. So I would have to buy separate compilers which