could anyone tell me why am I getting this error?

Code :

Exception in thread "main" java.lang.NumberFormatException: For input string: "datafile.txt"
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
	at java.lang.Integer.parseInt(Integer.java:492)
	at java.lang.Integer.parseInt(Integer.java:527)
	at postfixstack.Main.main(Main.java:27)
Java Result: 1

the file contains

1 + 2 - 3

I'm creating two stacks 1: operands, and 2: operators, and then displaying it

line 27 in Main contains "oprand.push(Integer.parseInt(next));"

Code :

package postfixstack;
 
import java.util.*;
 
public class Main {
 
    public static void main(String[] args)
    {
        Stack<String> optor = new Stack();
        Stack<Integer> oprand = new Stack();
 
        Scanner in = new Scanner("datafile.txt");
 
        while(in.hasNext())
        {
            String next = in.next();
            if(optor.isOperator(next))
                optor.push(next);
            else
            {
                oprand.push(Integer.parseInt(next));
            }
 
        }
 
        System.out.println("Operators");
        optor.display();
 
        System.out.println("Operands");
        oprand.display();
    }
 
}