HELP

package projekt;

public class Plus extends Operator {

    @Override
    public int prioritet() {
        // TODO Auto-generated method stub
        return 2;
    }

    @Override
    public void evaluera(Stack operand) {
        double ett=Double.parseDouble((String)operand.pop());
        double två=Double.parseDouble((String)operand.pop());
        operand.push(ett+två);

    }

    @Override
    public void hantera(Stack operator, Stack operand) {
        while(operator.empty()!=true&&((Operator) operator.top()).prioritet()>=this.prioritet()){
             ((Operator) operator.pop()).evaluera(operand);
        }

        operator.push(this);

    }

}





MAIN


package projekt;

import java.util.Scanner;

public class Main {

    static Stack operator;
    static Stack operand;
    static Scanner sc=new Scanner(System.in);
    static String string;


    public static void main (String[] args){
        operator=new Stack();
        operand=new Stack();
        System.out.println("Skriv in ditt tal");
        string=sc.nextLine();

        String[] in=string.split(" ");
        tilldela(in);
        System.out.println(operand.top());



    }

    public static void tilldela(String[] lista){
        for(String s: lista){
            switch(s){

            case "+":
                new Plus().hantera(operator, operand);
                break;

            case "-":
                new Minus().hantera(operator, operand);
                break;

            case "*":
                new Multi().hantera(operator, operand);
                break;

            case "/":
                new Division().hantera(operator, operand);
                break;

            case "(":
                new VParantes().hantera(operator, operand);
                break;

            case ")":
                break;
            default:
                operand.push(s);
                break;
            }

        }


    }
}