write a program in java input a number and check that number is prime or not

What is a Prime Number?

A prime number is a number that is only divisible by 1 or itself. For example, 11 is only divisible by 1 or itself. Other Prime numbers 2, 3, 5, 7, 11, 13, 17....

Note: 0 and 1 are not prime numbers. 2 is the only even prime number.
Java Program to check whether number is prime or not
Program Logic:

• We need to divide an input number, say 19 from values 2 to 19 and check the remainder. If remainder is 0 number is not prime.
• No number is divisible by more than half of itself. So we need to loop through just number To Check/2 . If input is 19, half is 9.5 and the loop will iterate through values 2 to 9
• If a number To Check is completely divisible by other number, flag isPrime is set to true and the loop is exited.

Program:

import java.util.*;
public class Prime_number
{
public static void main(String[] args)
{
  int remainder;
  boolean isPrime=true;
  int numberToCheck; // Enter the numberToCheckber you want to check for prime
  Scanner sc=new Scanner(System.in);
  System.out.println("Enter the number:");
  numberToCheck=sc.nextInt();
  //Loop to check whether the numberToCheckber is divisible any numberToCheckber other than 1 and iteself
  for(int i=2;i<=numberToCheck/2;i++)
  {
   //numberToCheckber is dived by itself
            remainder=numberToCheck%i;
            System.out.println(numberToCheck+" Divided by "+ i + " gives a remainder "+remainder);
           
       //if remainder is 0 than numberToCheckber is not prime and break loop. Elese continue loop
     if(remainder==0)
     {
        isPrime=false;
        break;
     }
  }
  // Check value true or false,if isprime is true then numberToCheckber is prime otherwise not prime
  if(isPrime)
     System.out.println(numberToCheck + " is a Prime numberToCheckber");
  else
     System.out.println(numberToCheck + " is not a Prime numberToCheckber");
    }
  }

Output:

Enter the number:
19

19 Divided by 2 gives a remainder 1
19 Divided by 3 gives a remainder 1
19 Divided by 4 gives a remainder 3
19 Divided by 5 gives a remainder 4
19 Divided by 6 gives a remainder 1
19 Divided by 7 gives a remainder 5
19 Divided by 8 gives a remainder 3
19 Divided by 9 gives a remainder 1
19 is a Prime numberToCheckber