JavaFX 控制器未初始化 UI 字段

Question

我正在通过 Scene Builder 开发 JavaFX 项目。我创建了一个相当长的 FXML 文件（我只报告了一个片段）和相关的控制器。此外，我写了我的申请 class:

public class Main extends Application {
    @Override
    public void start(Stage stage) {
        Parent root;
        try {
            root = FXMLLoader.load(getClass().getResource("myfxml.fxml"));
        } catch (IOException e) {
            e.printStackTrace();
            return;
        }

        Scene scene = new Scene(root);

        stage.setTitle("Popolamento dati Ambasciata");
        stage.setScene(scene);
        stage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}

FXML:

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

<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>

<GridPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="600.0" prefWidth="1150.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.FXController">
    ...
<children>
        <Button id="addobject" mnemonicParsing="false" onAction="#addobject" text="Add Object" GridPane.columnIndex="1" GridPane.halignment="CENTER" GridPane.rowIndex="10" />
        <TextField id="objectname" GridPane.columnIndex="1" GridPane.columnSpan="2" GridPane.rowIndex="1" />

控制器：

public class FXController {

@FXML Button addobject;
@FXML TextField objectname;

@FXML
public void addobject() {
    objectname.getText();
}
}

}

应用程序正确启动并调用了事件处理程序，但在访问TextField objectname 时，它为空。我哪里做错了？

Answer 1

您应该使用 fx:id 属性而不是 id。

如果你查看文档 here:

Assigning an fx:id value to an element creates a variable in the document's namespace that can later be referred to by variable dereference attributes

请注意，您仍然可以使用 id 属性：

Additionally, if the object's type defines an "id" property, this value will also be passed to the objects setId() method.

所以在你的情况下：

<Button fx:id="addobject" ... />
<TextField fx:id="objectname" ... />

JavaFX 控制器未初始化 UI 字段

JavaFX Controller not getting UI fields initialized

java

javafx