IO流的一编程题 -_J2SE

IO流的一编程题求助--在线等
从键盘输入若干个字符，当输入字符“#”时中止输入。统计输入字符的个数，并将他们按输入时的逆序输出。如：
输入：inputstream#
输出：maertstupni

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Java code

import java.io.*;import java.util.*;class hh {    public static void main(String[] args)throws Exception     {        BufferedReader br =             new BufferedReader(new InputStreamReader(System.in));        StringBuffer sb = new StringBuffer();        String line = null;        while((line=br.readLine())!=null){            if(line.equals("#"))                break;                        sb.append(line);            sb.reverse();            System.out.println(sb);        }    //    System.out.println("Hello World!");    }}
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Java codeimport java.util.Scanner;public class Test {    public static void main(String[] args) {        int num = 0;        Scanner input = new Scanner(System.in);        StringBuffer sb = new StringBuffer();        while(!input.hasNext("#")){            sb.append(input.next());        }                System.out.println(sb.length());        System.out.println(sb.reverse());    }}
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Java codeimport java.util.Scanner;public class Test {    public static void main(String[] args) {        Scanner in = new Scanner(System.in);        StringBuilder sd = new StringBuilder();        String s = "";        while(!(s = in.next()).equals("#"))        {            sd.append(s);        }        System.out.println(sd.toString().length());        System.out.println(sd.reverse());    }}