Mine

import java.util.Stack;
import java.util.StringTokenizer;
import java.net.*;

public class Calculate {
    private double plusVal;
    private double minusVal;
    private double mulVal;
    private double divVal;
	
    public static void main(String []args){
	Calculate calc = new Calculate();
	calc.parseTokens(args[0]);
	
    }	

    public void parseTokens(String uttrykk){
	String delim = "()*/-+";
	StringTokenizer str = new StringTokenizer(uttrykk, delim, true);
	Stack <String> stack = new Stack();
	
	while(str.hasMoreTokens()){
	    String token = str.nextToken();
	    stack.push(token);
	       
	}

	try{

	    while (stack.contains("(")){
		int index = stack.indexOf("(");
		stack.removeElementAt(index); //removing the ( operator
		
		while (stack.contains("*")){
		    int index2 = stack.indexOf("*");
		    stack.removeElementAt(index2); //removing the * operator
		    operatorMul(Double.parseDouble(stack.elementAt(index2-1)), Double.parseDouble(stack.elementAt(index2)));
		    stack.removeElementAt(index2);
		    stack.insertElementAt(Double.toString(mulVal), index2);
		    stack.removeElementAt(index2-1);
		
		}
	
		while (stack.contains("/")){
		    int index2 = stack.indexOf("/");
		    stack.removeElementAt(index2);
		    operatorDiv(Double.parseDouble(stack.elementAt(index2-1)), Double.parseDouble(stack.elementAt(index2)));
		    stack.removeElementAt(index2);
		    stack.insertElementAt(Double.toString(divVal), index2);
		    stack.removeElementAt(index2-1);
			
		}
		while (stack.contains("-")){
		    int index2 = stack.indexOf("-");
		    stack.removeElementAt(index2);
		    operatorMinus(Double.parseDouble(stack.elementAt(index2-1)), Double.parseDouble(stack.elementAt(index2)));
		    stack.removeElementAt(index2);
		    stack.insertElementAt(Double.toString(minusVal), index2);
		    stack.removeElementAt(index2-1);
			
		}
	 
		while (stack.contains("+")){
		    int index2 = stack.indexOf("+");
		    stack.removeElementAt(index2);	
		    operatorPlus(Double.parseDouble(stack.elementAt(index2-1)), Double.parseDouble(stack.elementAt(index2)));
		    stack.removeElementAt(index2);
		    stack.insertElementAt(Double.toString(plusVal), index2);
		    stack.removeElementAt(index2-1);
		
		}
	    }	
	    while (stack.contains(")")){
		int index = stack.indexOf(")");
		stack.removeElementAt(index); //removing the ) operator
	    }

	    while (stack.contains("*")){
		int index = stack.indexOf("*");
		stack.removeElementAt(index); //removing the * operator
		operatorMul(Double.parseDouble(stack.elementAt(index-1)), Double.parseDouble(stack.elementAt(index)));
		stack.removeElementAt(index);
		stack.insertElementAt(Double.toString(mulVal), index);
		stack.removeElementAt(index-1);
		
	    }
	
	    while (stack.contains("/")){
		int index = stack.indexOf("/");
		stack.removeElementAt(index);
		operatorDiv(Double.parseDouble(stack.elementAt(index-1)), Double.parseDouble(stack.elementAt(index)));
		stack.removeElementAt(index);
		stack.insertElementAt(Double.toString(divVal), index);
		stack.removeElementAt(index-1);
			
	    }
	    while (stack.contains("-")){
		int index = stack.indexOf("-");
		stack.removeElementAt(index);
		operatorMinus(Double.parseDouble(stack.elementAt(index-1)), Double.parseDouble(stack.elementAt(index)));
		stack.removeElementAt(index);
		stack.insertElementAt(Double.toString(minusVal), index);
		stack.removeElementAt(index-1);
			
	    }
	 
	    while (stack.contains("+")){
		int index = stack.indexOf("+");
		stack.removeElementAt(index);	
		operatorPlus(Double.parseDouble(stack.elementAt(index-1)), Double.parseDouble(stack.elementAt(index)));
		stack.removeElementAt(index);
		stack.insertElementAt(Double.toString(plusVal), index);
		stack.removeElementAt(index-1);
		
	    }
	 	 
	    if (stack.size() == 1){
		System.out.println("svaret er: "+stack.pop());
	    }  
	 
	}
	catch(Exception e)
	    {
		System.out.println("feil i uttrykk:"+e);
	    }
    }

    public double operatorPlus(double first, double last){
	return plusVal = first + last;	
    }
    public double operatorMinus(double first, double last){
	return minusVal = (first - last);
    }

    public double operatorMul(double first, double last){
	return mulVal = (first * last);
    }

    public double operatorDiv(double first, double last){
	return divVal = (first / last);
    }
}