javafx8 FXMLLoader返回null

Question

我相信這個唯一不同的是SceneBuilder的版本是8.3，我使用TreeTableView和TreeTableColumn與Oracle的Java 8 這裏是FXML

<?xml version="1.0" encoding="UTF-8"?> 

<?import javafx.scene.control.TreeTableColumn?> 
<?import javafx.scene.control.TreeTableView?> 

<TreeTableView maxHeight="1.7976931348623157E308" maxWidth="1.7976931348623157E308" minHeight="1" minWidth="1" prefHeight="400.0" prefWidth="600.0" showRoot="false" stylesheets="@org/cornova/AudioExplorer.css" xmlns="http://javafx.com/javafx/8.0.111" xmlns:fx="http://javafx.com/fxml/1" fx:controller="org.cornova.AudioExplorerController"> 
    <columns> 
    <TreeTableColumn fx:id="mixerName" editable="false" maxWidth="6000.0" minWidth="100.0" prefWidth="-1.0" text="Mixers" /> 
    <TreeTableColumn fx:id="lineNames" maxWidth="49.0" minWidth="100.0" prefWidth="-1.0" text="Lines" /> 
     <TreeTableColumn fx:id="controlNames" minWidth="100.0" prefWidth="-1.0" text="Controls" /> 
     <TreeTableColumn fx:id="formatsNames" minWidth="100.0" prefWidth="-1.0" text="Formats" /> 
    </columns> 
</TreeTableView> 

這裏是控制器類

/** 
* Sample Skeleton for 'AudioExplorer.fxml' Controller Class 
*/ 

package org.cornova; 

import java.net.URL; 
import java.util.ResourceBundle; 
import javafx.fxml.FXML; 
import javafx.scene.control.TreeTableColumn; 

public class AudioExplorerController { 

    @FXML // ResourceBundle that was given to the FXMLLoader 
    private ResourceBundle resources; 

    @FXML // URL location of the FXML file that was given to the FXMLLoader 
    private URL location; 

    @FXML // fx:id="mixerName" 
    private TreeTableColumn<?, ?> mixerName; // Value injected by FXMLLoader 

    @FXML // fx:id="lineNames" 
    private TreeTableColumn<?, ?> lineNames; // Value injected by FXMLLoader 

    @FXML // fx:id="controlNames" 
    private TreeTableColumn<?, ?> controlNames; // Value injected by FXMLLoader 

    @FXML // fx:id="formatsNames" 
    private TreeTableColumn<?, ?> formatsNames; // Value injected by FXMLLoader 

    @FXML // This method is called by the FXMLLoader when initialization is complete 
    void initialize() { 
     assert mixerName != null : "fx:id=\"mixerName\" was not injected: check your FXML file 'AudioExplorer.fxml'."; 
     assert lineNames != null : "fx:id=\"lineNames\" was not injected: check your FXML file 'AudioExplorer.fxml'."; 
     assert controlNames != null : "fx:id=\"controlNames\" was not injected: check your FXML file 'AudioExplorer.fxml'."; 
     assert formatsNames != null : "fx:id=\"formatsNames\" was not injected: check your FXML file 'AudioExplorer.fxml'."; 

    } 
} 

這裏是主類

package org.cornova; 

import java.net.URL; 
import javafx.application.Application; 
import javafx.beans.property.ReadOnlyStringWrapper; 
import javafx.fxml.FXMLLoader; 
import javafx.scene.Group; 
import javafx.scene.Scene; 
import javafx.scene.control.TreeTableColumn.CellDataFeatures; 
import javafx.scene.control.TreeItem; 
import javafx.scene.control.TreeTableColumn; 
import javafx.scene.control.TreeTableView; 
import javafx.stage.Stage; 
import javax.sound.sampled.AudioSystem; 
import javax.sound.sampled.Mixer; 
import javax.sound.sampled.Mixer.Info; 

/** 
* 
* @author walt 
*/ 
public class AudioExplorer extends Application { 

    private URL url; 
    private FXMLLoader explorerLoader; 
    private AudioExplorerController audioController; 

    @Override 
    public void start(Stage stage) throws Exception { 
     stage.setTitle("Audio Explorer"); 
     final Scene scene = new Scene(new Group(), 200, 400); 
     Group sceneRoot = (Group)scene.getRoot(); 
     try { 
      url = getClass().getResource("/AudioExplorer.fxml"); 
      explorerLoader = new FXMLLoader(url); 
      explorerLoader.setLocation(url); 
      audioController = explorerLoader.getController(); 
     } catch (Exception e) { 
      System.out.println(e); 
     }  
     //Creating the root element 
     TreeItem rootNode = new TreeItem(); 
     rootNode.setExpanded(true); 
     Info mixers[] = AudioSystem.getMixerInfo(); 
     rootNode = new TreeItem<>(mixers[0]); 
     //Creating tree items 
     for (int i = 0; i < mixers.length; i++) { 
      rootNode.getChildren().add(new TreeItem<>(mixers[i])); 
     } 

     //Creating a column 
     TreeTableColumn<Info,String> mixerInfo = new TreeTableColumn<>("Mixers"); 
     mixerInfo.setMaxWidth(1500); 

     //Defining cell content 
     mixerInfo.setCellValueFactory((CellDataFeatures<Info, String> p) -> 
      new ReadOnlyStringWrapper(p.getValue().getValue().getName())); 

     //Creating a tree table view 
     final TreeTableView<Info> treeTableView = new TreeTableView<>(rootNode); 
     treeTableView.getColumns().add(mixerInfo); 
     treeTableView.setMaxWidth(1500); 
     treeTableView.setShowRoot(false); 
     treeTableView.autosize(); 
     sceneRoot.getChildren().add(treeTableView); 
     stage.setScene(scene); 
     stage.show();  
    } 

    /** 
    * @param args the command line arguments 
    */ 
    public static void main(String[] args) { 
     launch(args); 
    } 

} 

這都是在netbeans 8.2下完成的。我已經完成了，也許在18個月前，這些基於場景構建器的圖形應用程序可能有幾十個。我當時發現的一件事是確保css和controller源的位置針對它們所在的名稱空間進行了調整，這反映在fxml中。

css文件是空的，因爲我在此時只在SceneBuilder中定義了它，這就是爲什麼我沒有包含它（只有註釋）。

有人認爲我從SceneBuilder開始時就記得，它傾向於默默地失敗。 Tnanks！

Answer 1

實際上您需要爲基於fxml創建的控制器加載fxml。又路過該位置兩次是沒有必要的：

url = getClass().getResource("/AudioExplorer.fxml"); 
explorerLoader = new FXMLLoader(url); 

try { 
    TreeTableView<?> audioExplorer = explorerLoader.load(); 
    audioController = explorerLoader.getController(); 
    ... 
} catch ... 

而且沒有理由保持在一個領域的FXMLLoader實例的引用。一旦你完成加載，只需提取你需要的信息並「放下」加載器引用。調用load第二時間應避免反正...

Answer 2

除了Fabian的回答，請注意，我已經寫了一些utility methods，這樣可以減少FXML裝載到一個單獨的語句，如：

TreeTableView<?> audioExplorer = FXMLLoaders.load(AudioExplorer.class); 

請注意，這是唯一可能不過，如果你堅持以下命名約定：

如果一個類「mypackage的< 名>。」加載FXML文件，那麼FXML文件 應該是在相同的包中，並且被命名爲「< 名稱>.fxml」。

該庫是開源的。也許你會發現它有用：

<dependency> 
    <groupId>org.drombler.commons</groupId> 
    <artifactId>drombler-commons-fx-core</artifactId> 
    <version>0.10</version> 
</dependency> 

你可以閱讀更多關於它在這裏： http://puces-blog.blogspot.ch/2015/03/drombler-commons-conventions-to.html