method to find if no is prime or not java code example

Example 1: how to check if number prime in java

public class PrimeNumberInJava
{
   public static void main(String[] args)
   {
      int a, b = 0, flag = 0;
      int number = 17;
      b = number / 2;
      if(number == 0 || number == 1)
      {
         System.out.println(number + " is not prime number");
      }
      else
      {
         for(a = 2; a <= b; a++)
         {
            if(number % a == 0)
            {
               System.out.println(number + " is not prime number.");
               flag = 1;
               break;
            }
         }
         if(flag == 0)
         {
            System.out.println(number + " is prime number.");
         }
      }
   }
}

Example 2: Program to check whether the number is prime or not in java

public class Main 
{
public static void main(String[] args) 
{
int num = 100;
boolean flag = false;
for (int i = 2; i <= num / 2; ++i) 
{
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");
}
}

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Java Example