Evaluate postfix expression

import java.util.Stack;

class EvaluationPostfixExpression {
    static int evaluatePostfix(String postfix) {
        // stack to store operand 
        Stack stack = new Stack<>();
        int ex1, ex2, result;
        int i = 0;
        while(i < postfix.length()) {
            char ch = postfix.charAt(i);
            if(isOperand(ch)) {
                // if it's operand then add into stack 
                stack.push(Character.getNumericValue(ch));
            } else {
                // pop 2 values from stack and apply operator and 
                //store result back to stack 
                ex2 = stack.pop();
                ex1 = stack.pop();
                result = 0; // default value
                switch(ch) {
                    case '+': 
                        result = ex1 + ex2;
                        break;
                    case '-': 
                        result = ex1 - ex2;
                        break;
                    case '*': 
                        result = ex1 * ex2;
                        break;
                    case '/': 
                        result = ex1 / ex2;
                        break;
                }
                stack.push(result);
            }
            i++;
        }
        // return the stack top
        return stack.pop();
    }
    private static boolean isOperand(char ch) {
        switch(ch){
            case '+':
            case '-':
            case '*':
            case '/':
            case '^':
            case '(':
            case ')':
                return false;
        }
        return true;
    }
	public static void main (String[] args) {
		String postfix = "234*+82/-";
		System.out.println("Postfix : " + postfix + ", Result : " + evaluatePostfix(postfix));
	}
}

Output
Postfix : 234*+82/-, Result : 10