题解 | #反转字符串#

import java.util.*;


public class Solution {
    /**
     * 反转字符串
     * @param str string字符串 
     * @return string字符串
     */
    public String solve (String str) {

        if (str == null || str.length() == 0) {
            return str;
        }

        Stack<Character> stack = new Stack<>();

        char[] chars = str.toCharArray();

        for (char c : chars) {
            stack.push(c);
        }

        StringBuilder result = new StringBuilder();

        while (!stack.isEmpty()) {
            result.append(stack.pop());
        }

        return result.toString();
    }
}