7，编程题: 用最有效率的方法算出2乘以8等於几?

2 << 3，

因为将一个数左移n 位，就相当于乘以了2 的n 次方，那么，一个数乘以8 只要将其左移3 位即可，

而位运算cpu 直接支持的，效率最高，所以，2 乘以8 等於几的最效率的方法是2 << 3。

答:Server端程序: 
package test; 
import java.net.*; 
import java.io.*; 

public class Server { 
    private ServerSocket ss; 
    private Socket socket; 
    private BufferedReader in; 
    private PrintWriter out; 
    public Server() { 
       try { 
           ss=new ServerSocket(10000); 
           while(true) { 
           socket = ss.accept(); 
           String RemoteIP = socket.getInetAddress().getHostAddress(); 
           String RemotePort = ":"+socket.getLocalPort(); 
           System.out.println("client comein!IP:"+RemoteIP+RemotePort); 
           in = new BufferedReader(new 
           InputStreamReader(socket.getInputStream())); 
           String line = in.readLine(); 
           System.out.println("Cleint send is :" + line); 
out = new PrintWriter(socket.getOutputStream(),true); 
out.println("Your Message Received!"); 
out.close(); 
in.close(); 
socket.close(); 
} 
}catch (IOException e) 
{ 
out.println("wrong"); 
} 
} 
public static void main(String[] args) 
{ 
new Server(); 
} 
}; 
Client端程序: 
package test; 
import java.io.*; 
import java.net.*; 

public class Client 
{ 
Socket socket; 
BufferedReader in; 
PrintWriter out; 
public Client() 
{ 
try 
{ 
System.out.println("Try to Connect to 127.0.0.1:10000"); 
socket = new Socket("127.0.0.1",10000); 
System.out.println("The Server Connected!"); 
System.out.println("Please enter some Character:"); 
BufferedReader line = new BufferedReader(new 

InputStreamReader(System.in)); 
out = new PrintWriter(socket.getOutputStream(),true); 
out.println(line.readLine()); 
in = new BufferedReader(new InputStreamReader(socket.getInputStream())); 
System.out.println(in.readLine()); 
out.close(); 
in.close(); 
socket.close(); 
}catch(IOException e) 
{ 
out.println("Wrong"); 
} 
} 
public static void main(String[] args) 
{ 
new Client(); 
} 
};