Java Program:

Example:

import java.util.Scanner;
public class NumberFactors{
  public static void main(String []args) {
    int num;
    Scanner userInput = new Scanner(System.in);
    System.out.print("Enter your number :");
    num = userInput.nextInt();

    System.out.println("Factors of "+num);
    for(int i=1; i<=num/2; i++) {
      if(num % i==0)
        System.out.print(i+" ");
    }
    System.out.print(num);
  }
}

Output:

  Enter your number : 18
  Factors of 18 : 1 2 3 6 9 18

You should know first :

Factor of N : All numbers which perfectly divides N

Main Logic :

for(int i=1; i<=num/2; i++) {
  if(num % i==0)  // Checking for the factor
    System.out.print(i+" ");
}
System.out.print(num);

We are running the loop num/2 Since, any number can have only factors under its half, except itself