Valid Parentheses

public class Solution {
public boolean isValid(String s) {
if (s == null || s.length() % 2 == 1) {
return false;
}
Stack<Character> stack = new Stack<>();
for (int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
if (c == '{' || c == '[' || c == '(') {
stack.push(c);
continue;
}
if (stack.isEmpty()) {
return false;
}
char top = stack.pop();
if ((top == '{' && c == '}')|| (top == '[' && c == ']') || (top == '(' && c == ')')) {
continue;
} else {
return false;
}
}
if (stack.isEmpty()) {
return true;
} else {
return false;
}
}
}