用java语言编写输入一些数字,并且用a结束,最后统计输入了多少个数字?

package com.testinterface ;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.*;

public class Test {
public static void main (String[] args)
{
BufferedReader cin = new BufferedReader( new InputStreamReader( System.in ) );
try
{
String str="";;
L:while(true)
{
String s = cin.readLine () ;
str+=s;
if(s.indexOf("a")!=-1)
{
break L;
}
System.out.print (s) ;
}
System.out.println ("in put count="+(str.length()-1)) ;
}
catch (IOException ex)
{
}
}

}