Java Introduction - The Coding Shala

Home >> Learn Java >> Java Introduction

Java Introduction

Java is an Object-Oriented Programming(OOP) language rather than process-oriented. Java is a multi-purpose and cross-platform programming language developed by Sun Microsystems. Java is simple and easy to use and Java is platform-independent language so being described as a "Write once, run anywhere".  Whenever we compile the Java code it produces bytecode. and Java Virtual Machine (JVM) works as an interpreter for the bytecode. 
Java Introduction - The Coding Shala

 The process-oriented programs contain a series of linear steps. C is a Procedural Programming language. Object-oriented programming organizes a program around its data that is an object and a set of the well-defined interface to that data.

Abstraction is a necessary part of object-oriented programming language. Abstraction is the process to hide certain details and only shows the essential features of the object. Encapsulation, Inheritance, and polymorphism are the main principles of OOP language. Encapsulation is the mechanism that binds code and the data together and prevents it from misuse. we can think encapsulation as a protective wrapper that keeps safe the code and data from being accessed by the other code defined outside the wrapper. In Java, Class is the basis of encapsulation. 

A class defines the structure and behavior (data and code) basically class is a blueprint. The class contains objects, each object of a given class contains the behavior defined by the class. Objects are referred to as instances of a class. whenever we create a class, we specify the code and data(like variables, methods) in it all these elements called members of the class.

Inheritance is a process by which one class can acquire the properties and methods of another class.  A class derived from another class is called subclass or child class, whereas the class from which a subclass is derived is called a superclass.

Polymorphism means "many forms". Polymorphism in Java is a concept by which we can perform a single action in different ways. In Java "compile-time and runtime polymorphism" is there.



We will discuss all these terms and topics in detail in later topics. This is just a brief introduction.


Block of Code

If two or more statements are grouped together between the opening and closing curly braces then its called blocks of code or code blocks. For example- 

for(int i=0;i<5;i++){ //begin a block
//code inside for loop
System.out.println("Value of i is: " + i);
}//end of block

Whitespace

In Java, whitespace is space, tab or newline. In Java, we do not need to follow any indentation rules. Java programs can be written all on one line or many.

Identifiers

In Java, identifiers are class names, method names, and variable names. Identifiers can have letters, numbers, underscore and dollar sign characters. There are some rules for identifiers like they must not start with a number and Java is case-sensitive so Var is different identifier than var.

Some examples of valid identifier are - 
Count
temp
var4
$test
var_one

some examples of invalid identifiers are-
1count
count-one
not/this

Literals

In Java, Literals are constant values. For examples 10, 34, 'X', 'Y', 22.22, "This is also" all are literals.

Comments

Comments are ignored by Java compilers. They used to describe the code and other useful information. There are single-line comments and multi-line comments in Java.

Java Keywords

In Java, there are currently 50 keywords that are reserved. These keywords cannot be used as names of classes, variables or methods. The following are the list of keywords - 
Java Keywords - The Coding Shala
The keyword const and goto are reserved but not used in java. In Java, true, false, and null are also reserved. 

Other Posts You May Like
Please leave a comment below if you like this post or found some error, it will help me to improve my content.
By

Comments

Post a Comment

Popular Posts from this Blog

Java Program to Convert Binary to Decimal - The Coding Shala

Home >> Java Programs >> Convert Binary to Decimal  Hey there, welcome back to another post. In this post, we will learn how to convert Binary to Decimal in Java. Java Program to Convert Binary to Decimal You have given a binary number, convert it to a decimal number. Example:  Input: 101 Output: 5 Input: 111 Output: 7 Binary to Decimal Conversion in Java Approach We will the below formula to convert binary to decimal: decimal number = (2^0) * (rightmost digit) + (2^1) * (second rightmost digit) + ...  for example:  binary number = 110 decimal number = 2^0 * 0 + 2^1 * 1 + 2^2 * 1 = 1 * 0 + 2 * 1 + 4 * 1 = 0 + 2 + 4 = 6 Java Program:  import java.util.Scanner; /** * https://www.thecodingshala.com/ */ public class Main { public static void printDecimal( int num) { int decimal = 0; int twos = 1; // 2^0 = 1 initial value while (num > 0) { int temp = num
Read more

N-th Tribonacci Number Solution - The Coding Shala

Home >> Programming >> N-th Tribonacci Number  Hey there, welcome back to another post. In this post, we will learn how to solve the N-th Tribonacci Number problem and will implement its solution in Java. N-th Tribonacci Number Problem Statement The Tribonacci sequence Tn is defined as follows: T0 = 0, T1 = 1, T2 = 1, and Tn+3 = Tn + Tn+1 + Tn+2 for n >= 0. Given n, return the value of Tn.  Example 1:  Input: n = 4 Output: 4 Explanation: T_3 = 0 + 1 + 1 = 2 T_4 = 1 + 1 + 2 = 4 N-th Tribonacci Number Java Solution using Bottom-Up DP This problem is similar to the Fibonacci series. We can solve it using the Bottom-Up approach of dynamic programming. Time Complexity: O(n) Space Complexity: O(n) The space complexity can be reduced to O(1) by using variables to store the previous three values instead of using an array. Java Program:  class Solution { public int tribonacci( int n) { if (n == 0) return 0; if (n == 1 || n == 2
Read more

Shell Script to Create a Simple Calculator - The Coding Shala

Home >> Scripting >> simple calculator Shell Script to Create a Simple Calculator Write a shell script to create a simple calculator using a switch-case statement? Code:  #! / bin / bash echo "simple calculator" sum = 0 i = "y" echo "enter first number" read n1 echo "enter second number" read n2 while [ $ i = "y" ] do echo "1.Addition" echo "2.Subtraction" echo "3.Multiplication" echo "4.Division" echo "Enter choice" read ch case $ch in 1 ) sum =$(echo " $n1 + $n2" | bc - l) echo "Addition is =" $ sum ;; 2 ) sum =$(echo "$n1 - $n2" | bc - l) echo "Sub is =" $ sum ;; 3 ) sum =$(echo "$n1 * $n2" | bc - l) echo "Mul is =" $ sum ;; 4 ) sum =$(echo "$n1 / $n2" | bc - l) echo "div is =" $ sum ;; * )echo "invalid choice" esac echo "Do y
Read more

Shell Script to find sum, product and average of given numbers - The Coding Shala

Home >> Scripting >> Sum, product and average Shell Script to find the sum, product, and the average of given numbers Read four integer numbers from the user and find the sum, product, and average of these four numbers? Code:  #! / bin / bash echo "enter four integers" read a b c d sum =$(echo "$a + $b + $c + $d" | bc - l) average=$(echo "$sum / 4" | bc - l) product=$(echo "$a * $b * $c * $d" | bc - l) echo "sum = $sum" echo "Average = $average" echo "Product = $product" Other Posts You May Like Shell script to print sum of the digits of a number Shell Script to print number in descending order Shell script to find out biggest number from three numbers Shell script to find out factorial of a number Shell Script to create a simple calculator Please leave a comment below if you like this post or found some error, it will help me to improve my content.
Read more

Java Program to Convert Decimal to Binary - The Coding Shala

Home >> Java Programs >> Convert Decimal to Binary  Hey there, welcome back to another post. In this post, we will learn how to convert decimal to binary in Java. Java Program to Convert Decimal to Binary You have given a decimal number. Write a Java program to convert decimal to binary. Example 1:  Input: 7 Output: 111 Input: 10 Output: 1010 Decimal to Binary Conversion using Array Approach To convert decimal to binary we can follow the below steps: Store the remainder in the array when we divide the number by 2. Divide the number by 2. Follow the above two steps until the number is above 0. Print the array in reverse order. For example:  4 % 2 = 0 => 4/2 = 2 2 % 2 = 0 => 2/2 = 1 1 % 2 = 1 => 1/2 = 0 Binary of 4 is: 100 Java Program:  import java.util.ArrayList; import java.util.List; import java.util.Scanner; /** * https://www.thecodingshala.com/ */ public class Main { public static void printBinary( int num) {
Read more