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
[sourcecode lang=”Java”]
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);
}
}
}
}
[/sourcecode]
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
[sourcecode lang=”java”]
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);
}
}
}
}
[/sourcecode]
Method 3 : Java Program to find Prime Number upto N number using Command line input
[sourcecode lang=”Java”]
class PrimeNumber
{
public static void main(String[] args)
{
int n,p;
n=Integer.parseint(args[0]);
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);
}
}
}
}
[/sourcecode]
Steps to run above program via command line :
- Compilation : C:\JavaPrograms>javac PrimeNumber.java
- Interpretation : C:\JavaPrograms>java PrimeNumber 20
Output :
2
3
5
7
11
13
17
19
for(int i=2 ; i & lt ; n ; i++)
{
p=0;
for(int j=2;j<i;j++)
what is this lt here?