My Application
class looks like this:
我的Application类看起来像这样:
public class Test extends Application {
private static Logger logger = LogManager.getRootLogger();
@Override
public void start(Stage primaryStage) throws Exception {
String resourcePath = "/resources/fxml/MainView.fxml";
URL location = getClass().getResource(resourcePath);
FXMLLoader fxmlLoader = new FXMLLoader(location);
Scene scene = new Scene(fxmlLoader.load(), 500, 500);
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
The FXMLLoader
creates an instance of the corresponding controller (given in the FXML
file via fx:controller
) by invoking first the default constructor and then the initialize
method:
FXMLLoader通过首先调用默认构造函数然后调用initialize方法来创建相应控制器的实例(通过fx:controller在FXML文件中给出):
public class MainViewController {
public MainViewController() {
System.out.println("first");
}
@FXML
public void initialize() {
System.out.println("second");
}
}
The output is:
输出是:
first
second
So, why does the initialize
method exist? What is the difference between using a constructor or the initialize
method to initialize the controller required things?
那么,为什么初始化方法存在?使用构造函数或初始化方法初始化控制器所需的东西有什么区别?
Thanks for your suggestions!
谢谢你的建议!
2 个解决方案
#1
69
In a few words: The constructor is called first, then any @FXML
annotated fields are populated, then initialize()
is called. So the constructor does NOT have access to @FXML
fields referring to components defined in the .fxml file, while initialize()
does have access to them.
简而言之:首先调用构造函数,然后填充任何@FXML注释字段,然后调用initialize()。因此构造函数无法访问引用.fxml文件中定义的组件的@FXML字段,而initialize()确实可以访问它们。
Quoting from the Introduction to FXML:
引自FXML简介:
[...] the controller can define an initialize() method, which will be called once on an implementing controller when the contents of its associated document have been completely loaded [...] This allows the implementing class to perform any necessary post-processing on the content.
[...]控制器可以定义一个initialize()方法,当它的相关文档的内容已经完全加载时,它将在实现控制器上调用一次[...]这允许实现类执行任何必要的帖子 - 处理内容。
#2
58
The initialize
method is called after all @FXML
annotated members have been injected. Suppose you have a table view you want to populate with data:
在注入所有@FXML注释成员之后调用initialize方法。假设您有一个要用数据填充的表视图:
class MyController {
@FXML
TableView<MyModel> tableView;
public MyController() {
tableView.getItems().addAll(getDataFromSource()); // results in NullPointerException, as tableView is null at this point.
}
@FXML
public void initialize() {
tableView.getItems().addAll(getDataFromSource()); // Perfectly Ok here, as FXMLLoader already populated all @FXML annotated members.
}
}
#1
69
In a few words: The constructor is called first, then any @FXML
annotated fields are populated, then initialize()
is called. So the constructor does NOT have access to @FXML
fields referring to components defined in the .fxml file, while initialize()
does have access to them.
简而言之:首先调用构造函数,然后填充任何@FXML注释字段,然后调用initialize()。因此构造函数无法访问引用.fxml文件中定义的组件的@FXML字段,而initialize()确实可以访问它们。
Quoting from the Introduction to FXML:
引自FXML简介:
[...] the controller can define an initialize() method, which will be called once on an implementing controller when the contents of its associated document have been completely loaded [...] This allows the implementing class to perform any necessary post-processing on the content.
[...]控制器可以定义一个initialize()方法,当它的相关文档的内容已经完全加载时,它将在实现控制器上调用一次[...]这允许实现类执行任何必要的帖子 - 处理内容。
#2
58
The initialize
method is called after all @FXML
annotated members have been injected. Suppose you have a table view you want to populate with data:
在注入所有@FXML注释成员之后调用initialize方法。假设您有一个要用数据填充的表视图:
class MyController {
@FXML
TableView<MyModel> tableView;
public MyController() {
tableView.getItems().addAll(getDataFromSource()); // results in NullPointerException, as tableView is null at this point.
}
@FXML
public void initialize() {
tableView.getItems().addAll(getDataFromSource()); // Perfectly Ok here, as FXMLLoader already populated all @FXML annotated members.
}
}