Question

我有2个按钮btn_openport和btn_closeport，其代码如下： btn_openport打开套接字并允许新连接：正常运行 btn_closeport在asynctask中在后台调用以下方法：

private static class closePort extends AsyncTask {
@Override
protected Object doInBackground(Object[] objects) {
    Boolean closestatus = new OpenClosePort(port).closePort();

            ......rest of code
}

class openclose {
    private Socket socket = null;
    private ServerSocket server = null;

    private static final String TAG = "ports";

    private int port;

    void openPort() {
        try {
            server = new ServerSocket(port);
            socket = server.accept();
        } catch () {
        }
        ..........
    }

    Boolean closePort() {
        Log.e(TAG + "/closePort", ">>> Closing Port : " + this.port);
        try {
            socket.close();

            return true;

        } catch (Exception e) {
            Log.e(TAG + "/closePort", "Error closing port: ", e);
            return false;
        }
    }
}

但是，当执行此用于关闭端口的代码时，尽管客户端已连接到套接字，但我却收到 NullPointerException 。

我该如何解决？

错误：：

11-05 12:06:35.938 533-533/com.app.fi E/MyActivity/closePort: >>> Closing Port : 5556
11-05 12:06:35.941 533-533/com.app.fi E/MyActivity/closePort: Error closing port: 
   11-05 14:18:55.102 7460-8810/com.app.fi E/MyActivity/closePort: >>> Closing Port : 5556
11-05 14:18:55.104 7460-8810/com.app.fi E/MyActivity/closePort: Error closing port: 
    java.lang.NullPointerException: Attempt to invoke virtual method 'void java.net.Socket.close()' on a null object reference
        at com.app.fi.OpenClosePort.closePort(OpenClosePort.java:54)
        at com.app.fi.MainActivity$closePort.doInBackground(MainActivity.java:83)
        at android.os.AsyncTask$2.call(AsyncTask.java:333)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:245)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
        at java.lang.Thread.run(Thread.java:764)
11-05 14:18:55.109 7460-8810/com.app.fi W/checkPortStatus: Printing Socket value : Socket[address=localhost/127.0.0.1,port=5556,localPort=45524]

Answer 1

为什么要创建一个用于关闭端口的新对象？在这一行

new OpenClosePort(port).closePort();

尝试创建OpenClosePort类的对象，并在关闭端口时使用相同的对象。

打开和关闭插座

1 个答案: