// 字符串反转
public class StringReverse {
    public static void main(String[] args) {
        String input="sdtrv";
        String reverseStr = reverse(input);
        System.out.println(reverseStr);
    }

    static String reverse(String input){
        StringBuilder tmp=new StringBuilder();
        for(char ch:input.toCharArray()){
            tmp.insert(0, ch);
        }
        return tmp.toString();
    }
}