how to print prime numbers and sum of the prime numbers in java code example

Example 1: Java program to print prime numbers upto n

// Java program to print prime numbers upto n
import java.util.Scanner;
public class PrimeNumberUptoN
{
   public static void main(String[] args)
   {
      Scanner sc = new Scanner(System.in);
      int a = 0;
      int n = 0;
      String strPrime = "";
      System.out.println("Please enter the value of n: ");
      int number = sc.nextInt();
      for(a = 1; a <= number; a++)
      {
         int counter = 0;
         for(n = a; n >= 1; n--)
         {
            if(a % n == 0)
            {
               counter = counter + 1;
            }
         }
         if(counter == 2)
         {
            strPrime = strPrime + a + " ";
         }
      }
      System.out.println("prime numbers upto n are: ");
      System.out.println(strPrime);
      sc.close();
   }
}

Example 2: sum of prime numbers in a digit in java

import java.util.*;
public class PrimeDigit
{
    public boolean IsPrime(int i)
    {
        boolean b=true;
        int d=2;
        while(d<i/2)
        {
            if (i%d==0)
            {
                b=false;
                break;
            }
            d++;
        }
        return b;
    }
    public static void main(String []args)
    {
       Scanner sc=new Scanner(System.in);
       System.out.print("Enter A Number : ");
       int i=sc.nextInt();
       int s=0,r;
       PrimeDigit pd=new PrimeDigit();
       while(i>0)
       {
            r=i%10;
            if(pd.IsPrime(r))
			{
                s = s + r;
			}
            i = i / 10;
       }
       System.out.print("Sum Of The Prime Digits : " + s );
    }
}