Aatul Palandurkar

Java Program to find prime number upto N number

Posted on: March 13, 2016

Objectives :

  • Write a Java program to find prime number upto N number
  • Write a Java program to print prime number upto N number
  • Write a Java program to find prime number upto N number using Command Line Arguments
  • Write a Java Program to find prime number upto N number via Command Line Arguments
  • Write a Java program to find prime number upto N number using Scanner class

 

Java Program / Code :

Method 1 : Java Program to find Prime Number upto N number using Scanner class


import java.util.Scanner;
class PrimeNumber
{
public static void main(String[] args)
{
int n,p;
Scanner s=new Scanner(System.in);
System.out.println(“Enter number : ”);
n=s.nextInt();
for(int i=2;i<n;i++)
{
p=0;
for(int j=2;j<i;j++)
{
if(i%j==0)
p=1;
}
if(p==0){
System.out.println(i);
}
}
}
}

Method 2 : Java Program to find Prime Number upto N number using Scanner class and writing function to find prime number

Method isPrime() for checking if a number is prime or not

public class PrimeNumber{
 public boolean isPrime(int num) {
 if ( num < 2 ){
 return false;
 }
 for (int i = 2; i <= Math.sqrt(num); i++) {
 if ( num % i == 0 ) {
 return false;
 }
 }
 return true;
 }
}


// Mock Test Class to test above code
import java.util.Scanner;

public class Demo
{
 public static void main(String[] args) 
 {
 Scanner scanner = new Scanner(System.in);

 System.out.println("Please enter a number: ");
 int num = scanner.nextInt();
 
 if ( num < 2 ) {
 System.out.println("\n There are no Prime Numbers available");
 System.exit(0);
 }
 System.out.println("\n Prime Numbers from 1 to "+ num);
 PrimeNumber primeNum = new PrimeNumber();

 for (int i = 3; i <= num; i++) {
 if ( primeNum.isPrime(i) ) {
 System.out.print(", " + i);
 }
 }
 } 
}

Method 3 : Java Program to find Prime Number upto N number using Command line input


class PrimeNumber
{
public static void main(String[] args)
{
int n,p;
n=Integer.parseint(args[0]);
for(int i=2;i&lt;n;i++)
{
p=0;
for(int j=2;j&lt;i;j++)
{
if(i%j==0)
p=1;
}
if(p==0){
System.out.println(i);
}
}
}
}

Steps to run above program via command line :

  1. Compilation : C:\JavaPrograms>javac PrimeNumber.java
  2. Interpretation : C:\JavaPrograms>java PrimeNumber 20

Output :

2

3

5

7

11

13

17

19

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,

1 Response to "Java Program to find prime number upto N number"

for(int i=2 ; i & lt ; n ; i++)
{
p=0;
for(int j=2;j<i;j++)
what is this lt here?

Like

Comments are closed.

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

Join 13,239 other followers

Tweets

YouTube

Archives

%d bloggers like this: