字符串反转--利用StringBuilder和普通方法对比

public String print(String s){
        String ch = " ";
        for (int i = s.length()-1; i >= 0; i--) {
            ch += s.charAt(i);
        }
        return ch;
    }
    public String stringReverse(String s){
        StringBuilder sb = new StringBuilder(s);

        sb.reverse();
        String s1 = sb.toString();
        return s1;
    }
}