Java Programs for Practice : Know the Simple Java Programs for Beginners

December 27, 2022 2023-01-03 11:43Java Programs for Practice : Know the Simple Java Programs for Beginners

# Java Programs for Practice : Know the Simple Java Programs for Beginners

Java is the universal standard for creating and distributing embedded and mobile apps, gaming, Website content, and enterprise solutions, and is the basis for nearly any other sort of networked program. **Java**, used by more than 9 million developers worldwide, streamlines the creation, distribution, and consumption of innovative software and services.

Practice and working through exercises are the most effective ways to learn new stuff. By working through the tasks, ranging from the simplest to the most advanced, you can get some hands-on experience with the Java programming language’s concepts.

Hopefully, you’ll put your newfound knowledge of Java to good use by completing these exercises. Enrich your Java fundamentals & programming skills by practicing exercises. Enroll in the top **Java training in Chennai** and elevate your career.

## Java Code for Printing an Integer

This program will teach you how to print a user-entered number in Java. System.in stores the integer in a variable, whereas System.out displays it on the screen.

import java.util.Scanner;

public class HelloWorld {

public static void main(String[] args) {

// Creates a reader instance which takes

// input from standard input – keyboard

Scanner reader = new Scanner(System.in);

System.out.print(“Enter a number: “);

// nextInt() reads the next integer from the keyboard

int number = reader.nextInt();

// println() prints the following line to the output screen

System.out.println(“You entered: ” + number);

}

**Output : **

Enter a number: 22

Entered by user: 22

### Addition of Two Integers Using Java

This program will teach you how to save and add two integers in Java. The full sum is displayed on the screen following addition.

class Main {

public static void main(String[] args) {

int first = 20;

int second = 30;

// add two numbers

int sum = first + second;

System.out.println(first + ” + ” + second + ” = ” + sum);

}

}

**Output**

Enter two numbers

20 30

The sum is: 50

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#### Computing Quotient and Remainder Using Java

This Java program will teach you how to determine the quotient and remainder from a given dividend and divisor.

public class QuotientRemainder {

public static void main(String[] args) {

int dividend = 26, divisor = 6;

int quotient = dividend / divisor;

int remainder = dividend % divisor;

System.out.println(“Quotient = ” + quotient);

System.out.println(“Remainder = ” + remainder);

}

}

**Output**

Quotient = 4

Remainder = 2

#### Multiplication of two Floating-Point Numbers Using Java

This application will teach you how to multiply two floating-point values in Java, save the result, and output it to the screen.

public class MultiplyTwoNumbers

{

public static void main(String[] args) {

float first = 2.5f;

float second = 3.0f;

float product = first * second;

System.out.println(“The product is: ” + product);

}

}

**Output**

The product is: 7.5

#### Determine whether a given integer is a palindrome

A palindrome is a number that produces the same result when reversed. We find the inverse of the provided integer and determine whether or not it is equivalent.

public static void main(String[] args)

{

Scanner in = new Scanner(System.in);

String str = in.nextLine();

int length = str.length();

boolean isPalindrome = true;

for(int i = 0; i < length; i++)

{

if(str.charAt(i) != str.charAt(length-1-i)) {

System.out.println(“Snot a palindrome.”);

isPalindrome = false;

break;

}

}

if(isPalindrome) {

System.out.println(“palindrome.”);

}

}

#### Programming in Java to Determine If a Number Is Even or Odd

This software teaches you how to determine whether a user-inputted number is even or odd. The Java if…else statement and ternary operator will be used to do this.

import java.util.Scanner;

public class EvenOdd {

public static void main(String[] args) {

Scanner reader = new Scanner(System.in);

System.out.print(“Enter a number: “);

int num = reader.nextInt();

if(num % 2 == 0)

System.out.println(num + ” is even”);

else

System.out.println(num + ” is odd”);

}

}

**Output**

Enter a number: 17

12 is odd

#### Determine Whether a Letter Is a Vowel or Consonant with a Java Program

You will discover how to use Java’s if..else and switch statements to determine whether an alphabet is a vowel or a consonant in this program.

public class VowelConsonant {

public static void main(String[] args) {

char ch = ‘i’;

if(ch == ‘a’ || ch == ‘e’ || ch == ‘i’ || ch == ‘o’ || ch == ‘u’ )

System.out.println(ch + ” is vowel”);

else

System.out.println(ch + ” is consonant”);

}

}

**Output**

i is vowel

#### Finding the Largest of Three Numbers in Java

You will discover how to use Java’s if else and nested if..else statements to determine which of three values is the largest in this application.

public class Largest {

public static void main(String[] args) {

double n1 = -2.5, n2 = 5.1, n3 = 7.5;

if( n1 >= n2 && n1 >= n3)

System.out.println(n1 + ” is the largest number.”);

else if (n2 >= n1 && n2 >= n3)

System.out.println(n2 + ” is the largest number.”);

else

System.out.println(n3 + ” is the largest number.”);

}

}

**Output**

7.5 is the largest number.

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#### Check the Leap Year with Java

You will learn how to determine whether a given year is a leap year in this program. A if statement is used to check this.

public class Main {

public static void main(String[] args) {

// year to be checked

int year = 2008;

boolean leap = false;

// if the year is divided by 4

if (year % 4 == 0) {

// if the year is century

if (year % 100 == 0) {

// if year is divided by 400

// then it is a leap year

if (year % 400 == 0)

leap = true;

else

leap = false;

}

// if the year is not century

else

leap = true;

}

else

leap = false;

if (leap)

System.out.println(year + ” is a leap year.”);

else

System.out.println(year + ” is not a leap year.”);

}

}

**Output**

2008 is not a leap year.

#### Programming in Java to Determine a Number's Positive or Negative Sign

You’ll discover how to determine whether a given number is positive or negative in this program. In Java, this is accomplished by using an if else statement.

public class PositiveNegative {

public static void main(String[] args) {

double number = 11.8;

// true if number is less than 0

if (number < 0.0)

System.out.println(number + ” is a negative number.”);

// true if number is greater than 0

else if ( number > 0.0)

System.out.println(number + ” is a positive number.”);

// if both test expression is evaluated to false

else

System.out.println(number + ” is 0.”);

}

}

**Output**

11.8 is a positive integer

#### Finding each Root of a Quadratic Equation Using Java

This application teaches you how to use Java’s format() method to locate the roots of a quadratic equation and print them.

public class Main {

public static void main(String[] args) {

// value a, b, and c

double a = 2.3, b = 4, c = 5.6;

double root1, root2;

// calculate the determinant (b2 – 4ac)

double determinant = b * b – 4 * a * c;

// check if determinant is greater than 0

if (determinant > 0) {

// two real and distinct roots

root1 = (-b + Math.sqrt(determinant)) / (2 * a);

root2 = (-b – Math.sqrt(determinant)) / (2 * a);

System.out.format(“root1 = %.2f and root2 = %.2f”, root1, root2);

}

// check if determinant is equal to 0

else if (determinant == 0) {

// two real and equal roots

// determinant is equal to 0

// so -b + 0 == -b

root1 = root2 = -b / (2 * a);

System.out.format(“root1 = root2 = %.2f;”, root1);

}

// if determinant is less than zero

else {

// roots are complex number and distinct

double real = -b / (2 * a);

double imaginary = Math.sqrt(-determinant) / (2 * a);

System.out.format(“root1 = %.2f+%.2fi”, real, imaginary);

System.out.format(“\nroot2 = %.2f-%.2fi”, real, imaginary);

}

}

}

**Output**

root1 = -0.87+1.30i and root2 = -0.87-1.30i

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#### Calculating the Sum of Natural Numbers using Java

You’ll discover how to use Java’s for loop and while loop to compute the sum of natural numbers in this application.

public class SumNatural

{

public static void main(String[] args)

{

int num = 100, sum = 0;

for(int i = 1; i <= num; ++i)

{

// sum = sum + i;

sum += i;

}

System.out.println(“Sum = ” + sum);

}

}

**Output**

Sum = 5050

#### Java Code to Determine the Factorial of a Number

In this program, you’ll discover how to use Java’s for and while loops to calculate the factorial of a given number.

public class Factorial {

public static void main(String[] args) {

int num = 10;

long factorial = 1;

for(int i = 1; i <= num; ++i)

{

// factorial = factorial * i;

factorial *= i;

}

System.out.printf(“Factorial of %d = %d”, num, factorial);

}

}

**Output**

Factorial of 5 = 120

#### Create multiplication tables using a Java program

You will discover how to create a multiplication table for a given integer in this program. Java’s for and while loops are used to do this.

public class MultiplicationTable {

public static void main(String[] args) {

int num = 5;

for(int i = 1; i <= 10; ++i)

{

System.out.printf(“%d * %d = %d \n”, num, i, num * i);

}

}

}

**Output**

4 * 1 = 4

4 * 2 = 8

4 * 3 = 12

4 * 4 = 16

4 * 5 = 20

4 * 6 = 24

4 * 7 = 28

4 * 8 = 32

4 * 9 = 36

4 * 10 = 40

#### Java Program to Calculate the GCD of Two Numbers

You will learn how to find the GCD of two numbers in Kotlin in this application. If else statements are used in conjunction with for and while loops to accomplish this.

class Main {

public static void main(String[] args) {

// find GCD between n1 and n2

int n1 = 81, n2 = 153;

// initially set to gcd

int gcd = 1;

for (int i = 1; i <= n1 && i <= n2; ++i) {

// check if i perfectly divides both n1 and n2

if (n1 % i == 0 && n2 % i == 0)

gcd = i;

}

System.out.println(“GCD of ” + n1 +” and ” + n2 + ” is ” + gcd);

}

}

**Output**

GCD of 81 and 153 is 9

#### Java Code to Calculate the LCM of Two Numbers

You will learn how to find the LCM of two numbers both using and without the GCD in this application. Java’s for and while loops are used to do this.

public class Main

{

public static void main(String[] args)

{

int n1 = 72, n2 = 120, lcm;

// maximum number between n1 and n2 is stored in lcm

lcm = (n1 > n2) ? n1 : n2;

// Always true

while(true) {

if( lcm % n1 == 0 && lcm % n2 == 0 ) {

System.out.printf(“The LCM of %d and %d is %d.”, n1, n2, lcm);

break;

}

++lcm;

}

}

}

**Output**

The LCM of 72 and 120 is 360.

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#### Loop-based Java Program to Present the Alphabet (A to Z)

This application teaches you how to use Java’s for loop to print the English alphabet in both upper- and lowercase.

class Main {

public static void main(String[] args) {

char c;

for(c = ‘A’; c <= ‘Z’; ++c)

System.out.print(c + ” “);

}

}

**Output**

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

class Main {

public static void main(String[] args) {

char c;

for(c = ‘a’; c <= ‘z’; ++c)

System.out.print(c + ” “);

}

}

**Output**

a b c d e f g h i j k l m n o p q r s t u v w x y z

#### Programming in Java to Reverse a Number

This application teaches you how to use Java’s while loop and for loop to reverse a number.

class Main {

public static void main(String[] args) {

int num = 1234, reversed = 0;

System.out.println(“Original Number: ” + num);

// run loop until num becomes 0

while(num != 0) {

// get last digit from num

int digit = num % 10;

reversed = reversed * 10 + digit;

// remove the last digit from num

num /= 10;

}

System.out.println(“Reversed Number: ” + reversed);

}

}

**Output**

Reversed Number: 4321

#### Java Program for Power-of-Number Calculation

You will discover how to compute a number’s power both with and without the help of the pow() function in this application.

class Main {

public static void main(String[] args) {

int base = 3, exponent = 4;

long result = 1;

while (exponent != 0) {

result *= base;

–exponent;

}

System.out.println(“Answer = ” + result);

}

}

**Output**

Answer = 81

#### Create a Java program to swap two numbers

There are two ways to accomplish this: with and without a third variable.

public static void swapNumberswithtemp(int a, int b) { //using 3rd variable

int temp = x;

x = y;

y = temp;

}

public static void swapNumberswithouttemp(int a, int b) {//without using 3rd variable

y = y + x;

x = y – x;

x = y – x;

}

public static void main(String[] args) {

int x = 15;

int y = 14;

swapNumbers(x, y);

System.out.printf(“%d %d”, x, y);

#### Create a program that will print each element of the Fibonacci series

A Fibonacci sequence is represented by Fib(n)=Fib(n-1)+Fib (n-2)

public static int fibonacci(int number){

if(number == 1 || number == 2){ //base case

return 1;

}

return fibonacci(number-1) + fibonacci(number -2);

}

public static void main(String args[]) {

int number = new Scanner(System.in).nextInt();

for(int i=1; i<=number; i++){

System.out.print(fibonacci2(i) +” “);

}

}

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public static int fibonacci(int number) {

if (number == 1 || number == 2) { //base case

return 1;

}

return fibonacci(number – 1) + fibonacci(number – 2);

}

public static void main(String args[]) {

int number = new Scanner(System.in).nextInt();

for (int i = 1; i <= number; i++) {

System.out.print(fibonacci2(i) + ” “);

}

}