JavaFX-需要帮助设置初始化阶段吗

当我试图在初始化时将stage设置为变量时，我不断得到一个

null

引用异常

我的密码

public class ListController implements Initializable {
        private Stage thisStage;

        @Override
        public void initialize(URL location, ResourceBundle resources) {
            lblCount.setText("Hey"); //This works

            thisStage = (Stage) lblCount.getScene().getWindow(); //this doesn't
        }

        public ListController()
        {
            thisStage = (Stage) lblCount.getScene().getWindow(); //this doesn't
        }
}

---

我尝试使用构造函数，但这也不起作用。

如果我们在Stage类中找到数据类型并相应地使用此类初始化，则可以解决此空引用

比如说,

Stage myStage = null ; // this will raise a null pointer reference exception the possible solution can be to say:

Stage myStage = {" ", 0, ' ', etc } ; // as long as the class Stage has data members like String, int, char, etc

---

获取阶段引用的一种方法是在控制器上创建一个方法并进行设置：

        FXMLLoader loader = new FXMLLoader();
        Parent node = loader.load(getClass().getResource("view.fxml").openStream());
        Scene scene = new Scene(node);

        Stage stage = new Stage();
        Controller controller = (Controller)loader.getController();

        controller.setPrimaryStage(stage);

        stage.show();

---

然后在您的方法中有一个有效的引用。

当您调用stage时，您可以通过如下方法传递stage引用

  Stage primaryStage = new Stage(); 
  FXMLLoader loader = new FXMLLoader();
  loader.setLocation(YourClass.class.getResource("yourpaht.fxml"));
  //here you change AnchorPane for your root Node
  rootLayout = (AnchorPane) loader.load();
  // Show scene.
  Scene scene = new Scene(rootLayout);
  primaryStage.setScene(scene);
  // Da acceso al programa principal.
  ListController controller = loader.getController();
  //method for passing the stage to the controller 
  controller.controlerPassing(this, primaryStage);
  // Show stage,
  primaryStage.show();

public class ListController implements Initializable {
      private Stage stage;
      pivate YourClass classs;

      public controlerPassing(YourClass classs, Stage stage){
        this.stage = stage;
        this.classs = classs;
      }

     @Override
     public void initialize(URL location, ResourceBundle resources) {
          lblCount.setText("Hey"); //This works
          //now you can do whatever you want whit the stage
          stage. do stuff........
     }
}

现在controller类看起来可以像这样

  Stage primaryStage = new Stage(); 
  FXMLLoader loader = new FXMLLoader();
  loader.setLocation(YourClass.class.getResource("yourpaht.fxml"));
  //here you change AnchorPane for your root Node
  rootLayout = (AnchorPane) loader.load();
  // Show scene.
  Scene scene = new Scene(rootLayout);
  primaryStage.setScene(scene);
  // Da acceso al programa principal.
  ListController controller = loader.getController();
  //method for passing the stage to the controller 
  controller.controlerPassing(this, primaryStage);
  // Show stage,
  primaryStage.show();

public class ListController implements Initializable {
      private Stage stage;
      pivate YourClass classs;

      public controlerPassing(YourClass classs, Stage stage){
        this.stage = stage;
        this.classs = classs;
      }

     @Override
     public void initialize(URL location, ResourceBundle resources) {
          lblCount.setText("Hey"); //This works
          //now you can do whatever you want whit the stage
          stage. do stuff........
     }
}

---

lblCount在哪里初始化？@BenWin要解决的第一个问题是空引用问题。在调用控制器的

initialize（）

方法时，FXML文件表示的UI尚未添加到

场景中。因此，
lblCount（）.getScene（）
在这里计算为
null
，得到一个
NullPointerException
。你到底想对窗口做什么？我只是想对实际的舞台/窗口做一个参考。因此，如果我想操纵舞台，我可以这样做。thistage.hide（）或thistage.bringtofront（）之类的。我不想每次想与舞台互动时都必须执行lblCont.getScene（）.getWindow（）.hide（）。有什么建议吗？