Which constructs a DataOutputStream？（）  A、 New dataInputStream（“in.txt”）；B、 New dataInputStream（new file（“in.txt”））；C、 New dataInputStream（new writer（“in.txt”））；D、 New dataInputStream（new FileWriter（“in.txt”））；E、 New dataInputStream（new InputStream（“in.tx

A、InputStream in=new FileReader(“file.txt”)

B、InputStream in=new FileInputStream(“file.txt”)

C、InputStream in=new InputStreamFileReader (“file.txt”,“read”)

D、FileInputStream in=new FileReader(new File(“file.txt”))

请完成下列Java程序：实现打印出自己的源文件的功能。

注意：请勿改动main()主方法和其他已有语句内容，仅在下划线处填入适当的语句。

import java.io.*;

import java.util.StringTokenizer;

public class ex27_2{

public static void main(String args[])throws IOException{

FileInputStream fis=new FileInputStream("ex27_2.java");

DataInputStream dis=new DataInputStream(fis);

String str=null;

while(true){

__________________;

if(str==null){

__________________;

}

StringTokenizer st=new StringTokenizer(str);

while(st.hasMoreTokens()){

System.out.print(st.nextToken()+ " " );

}

System.out.println();

}

}

}

在J2EE中，某一java程序中有如下代码：DataInputStream din=new DataInputStream（new BufferedInputStream（new FileInputStream（"employee.dat"）））；System.out.print（din.readByte（））；假设在employee.dat文件中只有如下一段字符：abcdefg。则：System.out在屏幕上打印（）。

A.a

B.b

C.97

D.98

A.Compilation fails.

B.Nothing is added to the file system.

C.Only a new file is created on the file system.

D.Only a new directory is created on the file system.

E.Both a new file and a new directory are created on the file system.

A. mv /old_dir/file /new_dir

B. mv -p /old_dir/file /new_dir

C. mv -k /old_dir/file /new_dir

D. mv /old_dir/file /new_dir/new_file

下面创建一个新文件对象方法错误的是( )。

A．File myFile; myFile=new File("mulu/file");

B．File myFile=new File();

C．myFile=new FileC/mulu","filel");

D．File myDir=new file("/mulu"); myFile=new File(Dir, "filer');