算法Valid Parentheses (in java)

Description：Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

An input string is valid if:

Open brackets must be closed by the same type of brackets.
Open brackets must be closed in the correct order.

Example 1:

Input: s = "()"
Output: true
Example 2:

Input: s = "()[]{}"
Output: true
Example 3:

Input: s = "(]"
Output: false
Example 4:

Input: s = "([)]"
Output: false
Example 5:

Input: s = "{[]}"
Output: true

Constraints:

1 <= s.length <= 104
s consists of parentheses only '()[]{}'.

After trying to finish this problem,I did solve the question with a not very good way.And I found a better solution on Internet.

class Solution {
    public boolean isValid(String s) {
        Stack<Character> x = new Stack<Character>();
        for(int i = 0; i < s.length(); i++){
            //判断，如果为左侧符号，压入栈中（先进后出）
            //检查字符用“==”，检查String用“isEqual()”
            if(s.charAt(i) == '{')
                x.push('}');
            else if(s.charAt(i) == '[')
                x.push(']');
            else if(s.charAt(i) == '(')
                x.push(')');
            else if(x.size() == 0 || x.pop() != s.charAt(i))
                return false;
        }
        return x.size() ==0;
   
    }
}

Quote:https://blog.csdn.net/yang_csdnForOBTS/article/details/79769746