Question

我正在使用Platform.RunLater来更新TextField。在这里你可以看到代码：

public class FXMLDocumentController implements Initializable {

    @FXML
    private TextField carlos;
    RXTX main = new RXTX();

    public void Test(){
    Platform.runLater(new Runnable() {
                    @Override public void run() {
                        carlos.setText("Test");    
                  }
                });

    }



    @Override
    public void initialize(URL url, ResourceBundle rb) {
        main.initialize();
        Thread t=new Thread() {
            public void run() {
                //the following line will keep this app alive for 1000 seconds,
                //waiting for events to occur and responding to them (printing incoming messages to console).
                try {Thread.sleep(1000000);} catch (InterruptedException ie) {}
            }
        };
        t.start();
        System.out.println("Started");
    }    

}

那：

public class RXTX implements SerialPortEventListener{


    private String Temperature;

        SerialPort serialPort;
        /** The port we're normally going to use. */
    private static final String PORT_NAMES[] = { 
            "COM4" // Windows
    };
    /**
    * A BufferedReader which will be fed by a InputStreamReader 
    * converting the bytes into characters 
    * making the displayed results codepage independent
    */
    private BufferedReader input;
    /** The output stream to the port */
    private OutputStream output;
    /** Milliseconds to block while waiting for port open */
    private static final int TIME_OUT = 2000;
    /** Default bits per second for COM port. */
    private static final int DATA_RATE = 9600;

    public void initialize() {
        CommPortIdentifier portId = null;
        Enumeration portEnum = CommPortIdentifier.getPortIdentifiers();

        //First, Find an instance of serial port as set in PORT_NAMES.
        while (portEnum.hasMoreElements()) {
            CommPortIdentifier currPortId = (CommPortIdentifier) portEnum.nextElement();
            for (String portName : PORT_NAMES) {
                if (currPortId.getName().equals(portName)) {
                    portId = currPortId;
                    break;
                }
            }
        }
        if (portId == null) {
            System.out.println("Could not find COM port.");
            return;
        }

        try {
            // open serial port, and use class name for the appName.
            serialPort = (SerialPort) portId.open(this.getClass().getName(),
                    TIME_OUT);

            // set port parameters
            serialPort.setSerialPortParams(DATA_RATE,
                    SerialPort.DATABITS_8,
                    SerialPort.STOPBITS_1,
                    SerialPort.PARITY_NONE);

            // open the streams
            input = new BufferedReader(new InputStreamReader(serialPort.getInputStream()));
            output = serialPort.getOutputStream();

            // add event listeners
            serialPort.addEventListener(this);
            serialPort.notifyOnDataAvailable(true);
        } catch (Exception e) {
            System.err.println(e.toString());
        }
    }

    /**
     * This should be called when you stop using the port.
     * This will prevent port locking on platforms like Linux.
     */
    public synchronized void close() {
        if (serialPort != null) {
            serialPort.removeEventListener();
            serialPort.close();
        }
    }

    /**
     * Handle an event on the serial port. Read the data and print it.
     */
    public synchronized void serialEvent(SerialPortEvent oEvent) {
        if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
            try {
                String inputLine=input.readLine();
                System.out.println(inputLine);
                                GetData(inputLine);
            } catch (Exception e) {
                System.err.println(e.toString());
            }
        }
        // Ignore all the other eventTypes, but you should consider the other ones.
    }

        @FXML
    private void GetData(String Data) {

            if(Data.contains("Temperature")){
                FXMLDocumentController main = new FXMLDocumentController();
                main.Test();
            }

        }
}

好吧，所以我没有工作。它返回一个错误：

runnable java.lang.NullPointerException中的异常 openpilot.FXMLDocumentController $ 1.run（FXMLDocumentController.java:35）在 com.sun.javafx.application.PlatformImpl $ 4 $ 1.run（PlatformImpl.java:182）在 com.sun.javafx.application.PlatformImpl $ 4 $ 1.run（PlatformImpl.java:179）在java.security.AccessController.doPrivileged（Native Method）at com.sun.javafx.application.PlatformImpl $ 4.run（PlatformImpl.java:179）在 com.sun.glass.ui.InvokeLaterDispatcher $ Future.run（InvokeLaterDispatcher.java:76） at com.sun.glass.ui.win.WinApplication._runLoop（Native Method）at com.sun.glass.ui.win.WinApplication.access $ 100（WinApplication.java:17）在 com.sun.glass.ui.win.WinApplication $ 3 $ 1.run（WinApplication.java:67）在java.lang.Thread.run（Thread.java:744）

Answer 1

请勿使用new创建FXML控制器，请使用FXMLLoader.load()。

在您的特定情况下，最好使用Platform.runLater（）在JavaFX应用程序线程上调用load（）。

FXMLLoader可以创建@FXML带注释节点的实例。因此，除非您使用加载器，否则永远不会创建@FXML节点。所以在这种情况下，你的＆＃34;卡洛斯＆＃34; TextField为null，因为没有任何东西会创建这样的TextField，导致你的NullPointerException。

NullPointerException错误与runLater工作或不工作无关。

您的代码中可能还有其他一些错误。

我建议在处理与串口通信的多线程应用程序之前，先花更多时间编写基本的单线程JavaFX应用程序。

稍后运行并不能使用JavaFX

1 个答案: