Trying to build a calculator in java but I keep getting the .class error -

i started java class summer program offering , tasked creating simple calculator. have different cases created , variables accounted reason keep getting .class error , have no clue know comes from:

cases(int fnum, int snum, string op);

import java.util.scanner;  public class day1{    public static void main(string [] args){       cases(int fnum, int snum, string op);    }    public static void input(){       scanner userinput = new scanner(system.in);        int fnum, snum;       string op;        system.out.println("enter first num: ");       fnum = userinput.nextint();        system.out.println("enter second num: ");       snum = userinput.nextint();        system.out.println("enter operation: ");       op = userinput.next();   }    public static void cases(int fnum, int snum, string op){       input();       switch(op){       case "+":          system.out.println(fnum + snum);          break;       case "-":          system.out.println(fnum - snum);          break;       case "*":          system.out.println(fnum * snum);          break;       case "/":          system.out.println(fnum / snum);          break;       default:          system.out.println(fnum % snum);          break;       }    }  } 

change code this.

 import java.util.scanner;  public class day1{     public static void main(string [] args){         int fnum = 5;         int snum = 5;         string op = "";         input(fnum, snum, op);     }     public static void input(int fnum, int snum, string op){         scanner userinput = new scanner(system.in);          system.out.println("enter first num: ");         fnum = userinput.nextint();          //rest of code          cases(fnum, snum, op);     }     public static void cases(int fnum, int snum, string op){            //your code     }  } 

you needed declare variables pass them function cases function can reference them. think teacher means keep things out of main don't input , cases code inside of main(). instead teacher wants use functions, you're doing.