java的交互 BuferedReader

import java.io.*;
import java.util.*;
public class TestBufferedReader 
{
	public static void main(String[] args)throws Exception 
	{
        BufferedReader  br = new BufferedReader(new InputStreamReader(System.in));
		String str="null";
		while((str=br.readLine())!=null){
		System.out.println(str);
		}

	}
}