Warum ist der COM4-Port meines Computers frei, während mein Telefonmodem ihn benutzt?

Question

Hier ist mein Code:

import java.io.*; 
import java.util.*; 
import javax.comm.*; 

public class SMS { 


    public static void main(String[] args) { 
      Enumeration lists=CommPortIdentifier.getPortIdentifiers(); 
      System.out.println(CommPortIdentifier.PORT_SERIAL); 
      System.out.println(lists.hasMoreElements()); 
      while (lists.hasMoreElements()){ 
       CommPortIdentifier cn=(CommPortIdentifier)lists.nextElement(); 

       if ((CommPortIdentifier.PORT_SERIAL==cn.getPortType())){ 
        System.out.println("Name is serail port "+cn.getName()+" Owned status "+cn.isCurrentlyOwned()); 

        try{ 
         SerialPort port1=(SerialPort)cn.open("ComControl",800000); 
         port1.setSerialPortParams(9600, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE); 
         System.out.println("Before get stream"); 
         OutputStream out=port1.getOutputStream(); 
         InputStream input=port1.getInputStream(); 
         System.out.println("Before write"); 
         out.write("AT".getBytes()); 
         System.out.println("After write"); 
         int sample=0; 
         //while(((sample=input.read())!=-1)){ 
         System.out.println("Before read"); 
          //System.out.println(input.read() + "Testing "); 
         //} 
          System.out.println("After read"); 
         System.out.println("Receive timeout is "+port1.getReceiveTimeout()); 
        }catch(Exception e){ 
         System.err.println(e.getMessage()); 
        } 
       } 

       else{ 
        System.out.println("Name is parallel port "+cn.getName()+" Owned status "+cn.isCurrentlyOwned()+cn.getPortType()+" "); 
       } 
      } 
    } 

} 

Dies ist die Ausgabe:

 
1 
true 
Name is serail port COM1 Owned status false 
Before get stream 
Before write 
After write 
Before read 
After read 
Receive timeout is -1 
Name is serail port COM2 Owned status false 
Before get stream 
Before write 
After write 
Before read 
After read 
Receive timeout is -1 
Name is serail port COM3 Owned status false 
Before get stream 
Before write 
After write 
Before read 
After read 
Receive timeout is -1 
Name is serail port COM4 Owned status false 
Before get stream 
Before write 
After write 
Before read 
After read 
Receive timeout is -1 
Name is parallel port LPT1 Owned status false2  
Name is parallel port LPT2 Owned status false2  

Mein COM4 durch mein Telefon-Modem verwendet wird, sondern nach dem Code seines Status ist frei. Gibt es etwas, das ich im Code verpasst habe und wie kann ich diese aussortieren?

Answer 1

Könnte es sein, dass die Software, die Ihr Telefon steuert, sich im Energiesparmodus befindet, oder so ähnlich?