In this article, we will understand how to display all the prime numbers from 1 to N in Java. All possible positive numbers from 1 to infinity are called natural numbers. Prime numbers are special numbers who have only two factors 1 and itself and cannot be divided by any other number.
A number is a prime number if its only factors are 1 and itself. 11 is a prime number. Its factors are 1 and 11 itself. Some examples of prime numbers are 2, 3, 5, 7, 11, 13 and so on. 2 is the only even prime number. All other prime numbers are odd numbers.
Below is a demonstration of the same −
Input
Suppose our input is −
Enter the value of n :10
Output
The desired output would be −
2 3 5 7
Algorithm
Step1- Start Step 2- Declare an integer : n Step 3- Prompt the user to enter an integer value/ Hardcode the integer Step 4- Read the values Step 5- Using a while loop from 1 to n, check if the 'i' value is divisible by any number from 2 to i. Step 6- If yes, check the next number Step 7- If no, store the number as a prime number Step 8- Display the 'i' value as LCM of the two numbers Step 9- Stop
Example 1
Here, the input is being entered by the user based on a prompt. You can try this example live in ourcoding ground tool .
import java.util.Scanner; public class PrimeNumbers{ public static void main(String arg[]){ int i,n,counter, j; Scanner scanner = new Scanner(System.in); System.out.println("Required packages have been imported"); System.out.println("A reader object has been defined "); System.out.print("Enter the n value : "); n=scanner.nextInt(); System.out.print("Prime numbers between 1 to 10 are "); for(j=2;j<=n;j++){ counter=0; for(i=1;i<=j;i++){ if(j%i==0){ counter++; } } if(counter==2) System.out.print(j+" "); } } }
Output
Required packages have been imported A reader object has been defined Enter the n value : 10 Prime numbers between 1 to 10 are 2 3 5 7
Example 2
Here, the integer has been previously defined, and its value is accessed and displayed on the console.
public class PrimeNumbers{ public static void main(String arg[]){ int i,n,counter, j; n= 10; System.out.printf("Enter the n value is %d ", n); System.out.printf("\nPrime numbers between 1 to %d are ", n); for(j=2;j<=n;j++){ counter=0; for(i=1;i<=j;i++){ if(j%i==0){ counter++; } } if(counter==2) System.out.print(j+" "); } } }
Output
Enter the n value is 10 Prime numbers between 1 to 10 are 2 3 5 7