Thread: Different approach to this code

Instructor informed me today that my code is similar to another students and I must redo it. I am not quite sure what to change to give her what she is asking for. Any suggestions? new to JAVA.

<import java.util.*;
import java.io.*;
import java.text.SimpleDateFormat;
 
public class A2RE5161843 {
 
    public static void main(String[] args) throws IOException {
        Scanner input = new Scanner(System.in);
        int firstNum = 0, secondNum = 0;
        boolean valid = false;
        while (!valid) {
            System.out.print("Enter first number :");
            firstNum = input.nextInt();
            if (firstNum < 0) {
                System.out.println("Enter positive number ");
            } else if (firstNum > 1000) {
                System.out.println("Enter number less than 1000");
            } else {
                valid = true;
            }
        }
        valid = false;
        while (!valid) {
            System.out.print("Enter second number :");
            secondNum = input.nextInt();
            if (secondNum < 0) {
                System.out.println("Enter positive number ");
            } else if (secondNum > 1000) {
                System.out.println("Enter number less than 1000");
            } else if ((secondNum - firstNum) < 10) {
                System.out.println("Second number should be at least 10 greater than first number");
            } else {
                valid = true;
            }
        }
        FileWriter fw = new FileWriter(new File("A2RE5161843.txt"));
        //Use a for loop to perform the following steps:
        //Continue writing to the same file as before.
        //Write ad label as before.
        //Output all odd numbers between firstNum and secondNum inclusive, one number per line.
        fw.write("1. All odd numbers between firstNum and secondNum inclusive");
        fw.write(System.getProperty("line.separator"));
        for (int i = firstNum; i <= secondNum; i++) {
            if (i % 2 != 0) {
                fw.write(i + "");
                fw.write(System.getProperty("line.separator"));
            }
        }
        //Output the sum of all numbers between firstNum and secondNum exclusive.
        fw.write("2. The sum of all numbers between firstNum and secondNum exclusive");
        fw.write(System.getProperty("line.separator"));
        int sum = 0;
        for (int i = firstNum + 1; i < secondNum; i++) {
            sum += i;
        }
        fw.write(sum + "");
        fw.write(System.getProperty("line.separator"));
        //Output all numbers from secondNum to firstNum in a single line with commas separating the numbers.
        fw.write("3. All numbers from secondNum to firstNum in a single line with commas separating the numbers");
        fw.write(System.getProperty("line.separator"));
        for (int i = firstNum; i <= secondNum; i++) {
            fw.write(i + ",");
        }
        fw.write(System.getProperty("line.separator"));
        //Write the date and time as the last line in the file in the format yyy-mm-dd hh:mm:ss.
        fw.write("4. The date and time as the last line in the file in the format yyy-mm-dd hh:mm:ss");
        fw.write(System.getProperty("line.separator"));
        fw.write((new SimpleDateFormat("yyyy-mm-dd hh:mm:ss")).format(new Date()));
        System.out.println("File Assignment2.txt written");
        fw.close();
    }
}>

thanks! Done!