ServerSocker.accept() 处的 java.lang.NullPointerException

Question

我遇到以下异常:

java.lang.NullPointerException at
 gr.test.asterisk.AsteriskServerSocket.run(AsteriskServerSocket.java:72)

这是我的代码:

public class AsteriskServerSocket  extends Thread{

    private Socket server = null;
    private ServerSocket serverSocket = null;
    private String serverPortString = null;

    public AsteriskServerSocket(){
         serverPortString = "50050";

        try {
            serverSocket = new ServerSocket(Integer.parseInt(serverPortString));
            serverSocket.setSoTimeout(1000000000);
        } catch (SocketTimeoutException s) {
            WriteExceptions.writeToFile(s);
        } catch (IOException e) {
            WriteExceptions.writeToFile(e);
        }
    }

    public void run() {
        while (true) {
            try {
                server = serverSocket.accept();<---- This is the line which I get the exception
                ......
            }
            } catch (SocketTimeoutException s) {
                System.err.println("Σφάλμα στην Server run. Socket timed out. \n" + s);
                break;
            } catch (IOException e) {
                System.err.println("Σφάλμα στην Server run.\n" + e);
                break;
            }
        }
    }
}

还有AsteriskServerSocket，我在主类中调用它:

public static void main(String[] args) {
    AsteriskServerSocket aSS = new AsteriskServerSocket();
}

我的操作系统是 CentOS 版本 5.10(最终版)，我的 JDK 版本是 1.8.0_45。我不知道为什么会抛出这个异常。我在这里遗漏了什么吗？

我在构造函数中的异常是:

My exception in the constructor is 0 :java.net.BindException: Address already in use at java.net.PlainSocketImpl.socketBind(Native Method) at java.net.AbstractPlainSocketImpl.bind(AbstractPlainSocketImpl.java:382) at java.net.ServerSocket.bind(ServerSocket.java:375) at java.net.ServerSocket.(ServerSocket.java:237) at java.net.ServerSocket.(ServerSocket.java:128)

Answer 1

您忽略构造函数中的异常并将其写入日志，因此 serverSocket 为 null。检查日志和/或重新抛出这些异常。