Valid Parentheses

public class Solution {
    public boolean isValid(String s) {
		// Start typing your Java solution below
		// DO NOT write main() function
		Stack<Character> stack = new Stack<Character>();
		for(int i = 0; i < s.length(); i++){
			char cur = s.charAt(i);
			if(cur == '(' || cur == '[' || cur == '{')
				stack.push(cur);
			else if(cur == ')'){
				if(stack.empty() || stack.pop() != '(')
					return false;
			}
			else if(cur == ']'){
				if(stack.empty() || stack.pop() != '[')
					return false;
			}
			else if(cur == '}'){
				if(stack.empty() || stack.pop() != '{')
					return false;
			}
		}
		if(!stack.empty())
			return false;
		return true;
	}
}