making list of prime numbers java

Now let’s learn java program to print prime numbers in a given range.

public class PrimeNumberRangeDemo 
{
   public static void main(String[] args) 
   {
      int lowerRange = 10, higherRange = 50;  
      while(lowerRange < higherRange) 
      {
         boolean flag = false;
         for(int a = 2; a <= lowerRange / 2; ++a) 
         {
            if(lowerRange % a == 0)
            {
               flag = true;
               break;
            }
         }
         if(!flag && lowerRange != 0 && lowerRange != 1)
             System.out.print(lowerRange + " ");
         ++lowerRange;
      }
   }
}

Now let’s see print first 10 prime numbers in java.

public class FirstTenPrimeNumbers
{
   public static void main(String[] args) 
   {
      int count = 0, number = 0, a = 1, b = 1;  
      while(number < 10)  
      {  
         b = 1;  
         count = 0;  
         while(b <= a)  
         {  
            if(a%b == 0)  
                count++;  
            b++;
         }  
         if(count == 2)  
         {  
            System.out.printf("%d ", a);  
            number++;  
         }  
         a++;  
      }
   }
}

public class Prime {

    public static void main(String[] args) {

        int num = 29;
        boolean flag = false;
        for(int i = 2; i <= num/2; ++i)
        {
            // condition for nonprime number
            if(num % i == 0)
            {
                flag = true;
                break;
            }
        }

        if (!flag)
            System.out.println(num + " is a prime number.");
        else
            System.out.println(num + " is not a prime number.");
    }
}