Print Prime Number in Given Range

In this tutorial we will learn to write a Java program that will output all prime numbers that are in a given range.

Problem

1. Our program takes two numbers as input.
2. Now the program will output all prime numbers between 3 and 13.
3. So the output will be 3, 5, 7, 11 and 13. Because these are the only five numbers that are prime numbers.

What is a prime number?

Prime numbers are the numbers that have only 2 factors: 1 and the number itself. It is defined only for the number that is greater than 1. 2′ is the smallest prime number.

Some examples

1. 7 is a prime number because only the factors of 7 are ‘1 and 7’.
2. 11 is a prime number because only the factors of 11 are ‘1 and 11’.
3. 10 is not a prime number because the factors of 10 are ‘1,2,5 and 10’.

Print prime number in Java in given range

import java.util.*;

public class Main {
	
    public static void main(String[] args) {
	    int i=0,fNum,sNum, temp,temp1=1;
	    Scanner sc = new Scanner(System.in);
	    System.out.println("Please give the first number");
	    fNum= sc.nextInt();
	    System.out.println("Please give the second number");
	    sNum= sc.nextInt();
	    System.out.println("Prime numbers in range "+fNum+ " and " +sNum+"are");
	    
	    while(fNum<=sNum){
	        temp=0;
	        for(i=2;i<=(fNum/2);i++){
	            if(fNum%i==0){
	                temp=1;
	                break;
	            }
	        }
	        if(temp==0)
	            System.out.println(fNum);
	        fNum++;
	    }
    
   }
}

Explanation

The numbers entered are 3 and 25, so our program checks all numbers less than 25 and greater than 3. The numbers that have no other factor than 1 and themselves, i.e. prime numbers in the given range are 3, 5, 7, 11, 13, 17, 19, 23

Output

Please give the first number
3
Please give the second number
25
Prime numbers in range 3 and 25are
3
5
7
11
13
17
19
23

.