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) {
	  //如果为空返回""
        // write code here
        if(str==null||str==""){
            return "";
        }
	  //用栈的反转来找出反转字符串
        int len=str.length();
        Stack<Character> stack=new Stack<>();
        for(int i=0;i<len;i++){
            stack.add(str.charAt(i));
        }
        String returnStr="";
        while(!stack.isEmpty()){
            returnStr+=stack.pop();
        }


        return returnStr;
    }
}