使用FXML将setText转换为TextFiend JavaFX

Question

I have that java class. It's initialized in JavaClassContainer . The problem is that it returns that error: java.lang.NullPointerException . A no set the text to the textfield .

import gnu.io.CommPortIdentifier; 
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent; 
import gnu.io.SerialPortEventListener; 
import java.io.BufferedReader;
import java.io.InputStreamReader; 
import java.io.OutputStream; 
import java.util.Enumeration;
import javafx.fxml.FXML;
import javafx.scene.control.TextField;

public class RXTX implements SerialPortEventListener{

    @FXML private static TextField carlos;

   // MORE CODE
@FXML
    private void GetData(String Data) {
            if(Data.contains("Temperature")){
                carlos.setText("Hola");
            }
        }
}

If I put a System.Out.Println for instance it works. So, The problem is in the setText to the TextField no in GetData class.

Ok, I will put also the main controller:

public class FXMLDocumentController implements Initializable {

    @FXML
    private Label label;

    @FXML
    private void handleButtonAction(ActionEvent event) {
        System.out.println("You clicked me!");
        label.setText("Hello World!");
    }

    @Override
    public void initialize(URL url, ResourceBundle rb) {
        RXTX main = new RXTX();
        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");
    }    

}

Answer 1

Well - what makes you believe that your RXTX.carlos is injected a value? You are creating the instance yourself so you are responsible to set a value to the STATIC field there.

I think you should:

1. learn about how to use a debugger in your IDE
2. learn more about how FXML works