我的方法不抽象，不能覆蓋另一種方法

Question

我一直在試圖創建一個音樂播放器，並且需要聽一個時間滑塊。所以我加入的時間幻燈片，這是我得到的錯誤：

我一直在試圖讓我的頭圍繞如何解決這個錯誤，並覆蓋全業務。

任何人都可以指出我正確的方向如何解決這個錯誤？

我的代碼：

public class graphicalController implements Initializable 
{ 
    //GUI Decleration 
    @FXML 
    public Button centreButton; 
    @FXML 
    public Button backButton; 
    @FXML 
    public Button forwardButton; 
    @FXML 
    public ToggleButton muteToggle; 
    @FXML 
    public MenuItem loadFolder; 
    @FXML 
    public Text nameText; 
    @FXML 
    public Text albumText; 
    @FXML 
    public Text timeText; 
    @FXML 
    public Text artistText; 
    @FXML 
    public Slider timeSlider; 
    @FXML 
    public Slider volumeSlider; 

    //Controller Decleration 
    String absolutePath; 
    SongQueue q = new SongQueue(); 
    MediaPlayer player; 
    Status status; 
    boolean isPlaying = false; 
    boolean isMuted = false; 
    boolean isPaused = false; 
    private Duration duration; 

    /** 
    * The constructor. The constructor is called before the initialize() 
    * method. 
    * 
    * Anything in regards to CSS styling with FXML MUST be done within the initialize method. 
    */ 

    public graphicalController() { 

    } 

    /** 
    * Initializes the controller class. This method is automatically called 
    * after the fxml file has been loaded. 
    */ 

    @FXML 
    public void initialize(URL location, ResourceBundle resources) 
    { 

     centreButton.setStyle("-fx-background-image: url('/Resources/Play_Button.png')"); 
     centreButton.setText(""); 

     backButton.setStyle("-fx-background-image: url('/Resources/Back_Button.png')"); 
     backButton.setText(""); 

     forwardButton.setStyle("-fx-background-image: url('/Resources/Forward_Button.png')"); 
     forwardButton.setText(""); 

     muteToggle.setStyle("-fx-background-image: url('/Resources/ToggleSound_Button.png')"); 
     muteToggle.setText(""); 

     nameText.setText(""); 
     albumText.setText(""); 
     artistText.setText(""); 

     volumeSlider.valueProperty().addListener(new ChangeListener<Number>() { 
       @Override 
       public void changed(ObservableValue<? extends Number> observable, 
       Number oldValue, Number newValue) { 
        double sliderValue = newValue.intValue(); 
        handleVolumeSlider(sliderValue); 
       } 
      }); 

     timeSlider.valueProperty().addListener(new ChangeListener<Number>() { 
       @Override 
       public void changed(ObservableValue<? extends Number> observable, 
       Number oldValue, Number newValue) { 

        //outputTextArea.appendText("Slider Value Changed (newValue: " + newValue.intValue() + ")\n"); 
       } 
      }); 

     timeSlider.valueProperty().addListener(new InvalidationListener() { 
       public void invalidated(Observable ov) { 
        if (timeSlider.isValueChanging()) { 
         // multiply duration by percentage calculated by slider position 
         if(duration!=null) { 
          player.seek(duration.multiply(timeSlider.getValue()/100.0)); 
         } 
         updateValues(); 
        } 
       } 
      }); 

    } 


    public void setSongText() { 
     String file = q.peek().fileName; 
     String songName = q.peek().songName; 
     String albumName = q.peek().albumName; 
     String artistName = q.peek().artistName; 
     if (songName == "") { 
      songName = "Song name not specified in metadata."; 
     } 
     else if (albumName == "") 
     { 
      albumName = " Album name not specified in metadata."; 
     } 
     else if (artistName == "") 
     { 
      artistName = "Artist name not specified in metadata."; 
     } 
     nameText.setText(songName); 
     albumText.setText(albumName); 
     artistText.setText(artistName); 
    } 
} 

你會發現我在初始化方法的問題。

Answer 1

您使用的是正確的Observable類型嗎？它應該是javafx.beans.Observable。