Javafx mediaViewer / mediaPlayer引发java.lang.reflect.InvocationTargetException和java.lang.NullPointerException

Question

So I have this code here:

package sample;

import javafx.beans.binding.Bindings;
import javafx.beans.property.DoubleProperty;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.media.Media;
import javafx.scene.media.MediaPlayer;
import javafx.scene.media.MediaView;
import javafx.stage.FileChooser;

import java.io.File;
import java.net.URL;
import java.util.ResourceBundle;

public class Controller implements Initializable {

    private MediaPlayer mediaPlayer;

    @FXML
    private MediaView mediaView;

    private String filePath;

    @FXML
    private void handleButtonAction (ActionEvent event){
        FileChooser fileChooser = new FileChooser();
        FileChooser.ExtensionFilter filter = new FileChooser.ExtensionFilter("Select a File (*.mp4)", "*.mp4");
        fileChooser.getExtensionFilters().add(filter);
        File file = fileChooser.showOpenDialog(null);
        filePath = file.toURI().toString();

        if(filePath != null) {
            Media media = new Media(filePath);
            mediaPlayer = new MediaPlayer(media);
            mediaView.setMediaPlayer(mediaPlayer);
            DoubleProperty width = mediaView.fitWidthProperty();
            DoubleProperty hight = mediaView.fitHeightProperty();

            width.bind(Bindings.selectDouble(mediaView.sceneProperty(), "width"));
            hight.bind(Bindings.selectDouble(mediaView.sceneProperty(), "hight"));

            mediaPlayer.play();
        }
    }

    @Override
    public void initialize(URL url, ResourceBundle rb) {
        // TODO
    }
}

And you can run it. But if you try to open a file using the openfile button, the video wont appear and I just get a list of exceptions. I'dont know if it's just me or if I did something wrong.

The NullPointerExeption is in line 38, trusting IntelliJ wich I am using.

Caused by: java.lang.NullPointerException
 at sample.Controller.handleButtonAction(Controller.java:38))

So is it something with the mediaPlayer/mediaViewer then? (mediaView.setMediaPlayer(mediaPlayer);)

Answer 1

所以我忘了做这行（或通过SceneBuilder添加）

<MediaView fx:id="mediaView" fitHeight="200.0" fitWidth="200.0" />