Evaluating post fix expression

EvaluatingPostFix.java

public static String operators = "+-^*/";

public static void main(String[] args){
    System.out.println(evaluatePostFix("6 2 3 + - 3 8 2 / + * 2 ^ 3 +"));
}

private static int evaluatePostFix(final String infix) {
    Stack<Integer> numberStack = new Stack<>();
    String[] infixCharacters = infix.split("");
    for (String i: infixCharacters) {
        if (i.equals(" ")) {
            continue;
        } else if (isOperator(i)) {
            if (numberStack.size() >=2) {
                int operand2 = numberStack.pop();
                int operand1 = numberStack.pop();
                int operatorActioned = actionOperator(operand1, operand2, i);
                if (operatorActioned != Integer.MIN_VALUE) {
                    numberStack.add(operatorActioned);
                }
            }
        } else {
            numberStack.add(Integer.parseInt(i));
        }
    }
    return numberStack.pop();
}

private static int actionOperator(int operand1, int operand2, String operator) {
    switch (operator) {
        case("+"):
            return operand1 + operand2;
        case("-"):
            return operand1 - operand2;
        case("^"):
            return (int) Math.pow(operand1, operand2);
        case("*"):
            return operand1 * operand2;
        case("/"):
            if (operand2 == 0) {
                return Integer.MIN_VALUE;
            }
            return operand1 / operand2;
        default:
            return Integer.MIN_VALUE;
    }
}

private static boolean isOperator(String i) {
    return operators.contains(i);
}