Aim: To write a Java program that prompts the user for an integer and then prints out all prime numbers up to that integer.

import java.io.*;
import java.lang.*;

class Demo
{
int step,i,k;
void prime(int n)
{
       System.out.println("prime numbers are as follows");
       for(i=2;i<=n;i++)
       {
step=1;
for(k=2;k<=(i/2);k++)
{
  if(i%k==0)
   step=0;
               }
          if (step==1)
            System.out.println(" "+i);
                   }
               }
}
class PrimeDemo
{
public static void main(String args[])throws IOException
 {
      InputStreamReader obj=new InputStreamReader(System.in);
      BufferedReader br=new BufferedReader(obj);
      System.out.println("enter last number");
      int n=Integer.parseInt(br.readLine());
      Demo ob=new Demo();
      ob.prime(n);
    }
}