JavaFX Embedded Table FXML 给出空指针异常

Question

我正在尝试通过参考 YT 的一些教程来创建 table 视图。当我做一个简单的 table 视图及其相关控制器时，它就可以工作了。

主要Class:

    public class TableTest extends Application {

    public TableTest() {
        // TODO Auto-generated constructor stub
    }

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

    @Override
    public void start(Stage stage) throws Exception {
        try {
            // load the fxml file
            FXMLLoader tableloader = new FXMLLoader(getClass().getResource("TestTableView.fxml"));
            Parent root = tableloader.load();

            TableTestController controller = tableloader.getController();
            controller.initializeModel();

            //load the login scene
            Scene scene = new Scene(root, 800, 400);
            stage.setTitle("Test Table Screen");
            stage.setScene(scene);
            stage.show();

        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

控制器Class：

public class TableTestController {

    @FXML private  TableView<TablePost> t_posts ;
    @FXML private  TableColumn<TablePost, String> c_post_id ;
    @FXML private  TableColumn<TablePost, String> c_post_title ;
    @FXML private  TableColumn<TablePost, String> c_post_desc ;
    @FXML private  TableColumn<TablePost, String> c_post_creator ;

    @FXML private TabPane TabPane;
    @FXML private Tab AllPosts;
    @FXML private AnchorPane t_anch;
    @FXML private TableTestController t_anchController;

    @FXML private Parent TAllPosts;

    public void initializeModel() {
        System.out.println("Starting Table Init");
        c_post_id.setCellValueFactory(new PropertyValueFactory<TablePost, String>("postId"));
        c_post_title.setCellValueFactory(new PropertyValueFactory<TablePost, String>("postTitle"));
        c_post_desc.setCellValueFactory(new PropertyValueFactory<TablePost, String>("postDesc"));
        c_post_creator.setCellValueFactory(new PropertyValueFactory<TablePost, String>("postCreator"));
        t_posts.setItems(getPosts());
        System.out.println("Finished Table Init");
   }

    public ObservableList<TablePost> getPosts() {
        ObservableList<TablePost> posts = FXCollections.observableArrayList();
        TablePost p1 ;
        p1 = new TablePost("id1","title1","desc1","creator1");
        posts.add(p1);
        p1 = new TablePost("id2","title2","desc2","creator2");
        posts.add(p1);
        return posts;
    }

}

TestTableView.fxml :

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

<?import javafx.scene.control.TableColumn?>
<?import javafx.scene.control.TableView?>
<?import javafx.scene.control.cell.PropertyValueFactory?>
<?import javafx.scene.layout.AnchorPane?>

<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity"
    minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0"
    prefWidth="600.0" xmlns="http://javafx.com/javafx/11.0.1"
    xmlns:fx="http://javafx.com/fxml/1"
    fx:id ="t_anch"
    fx:controller="test.TableTestController">

    <children>
        <TableView fx:id="t_posts" layoutX="14.0" layoutY="65.0"
            prefHeight="141.0" prefWidth="570.0">
            <columns>
                <TableColumn fx:id="c_post_id" prefWidth="78.0"
                    text="Post Id" />
                <TableColumn fx:id="c_post_title" prefWidth="135.0"
                    text="Post Title" />
                <TableColumn fx:id="c_post_desc" prefWidth="237.0"
                    text="Post Desc" />
                <TableColumn fx:id="c_post_creator" prefWidth="119.0"
                    text="Post Creator" />
            </columns>
        </TableView>
    </children>
</AnchorPane>

所有这些都有效，但是此刻，我将此 fxml 注入到选项卡视图中，我得到了 NPE。也就是说，如果我在 Main class 中更改第 28 行以引用基于新选项卡的 fxml，它会失败

这个有效：FXMLLoader tableloader = new FXMLLoader(getClass().getResource("TestTableView.fxml"));

这不起作用：FXMLLoader tableloader = new FXMLLoader(getClass().getResource("TestTableView2.fxml"));

TestTableView2.fxml :

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

<?import javafx.scene.control.Tab?>
<?import javafx.scene.control.TabPane?>
<?import javafx.scene.layout.BorderPane?>

<BorderPane maxHeight="-Infinity" maxWidth="-Infinity"
    minHeight="-Infinity" minWidth="-Infinity" prefHeight="515.0"
    prefWidth="714.0" xmlns="http://javafx.com/javafx/11.0.1"
    xmlns:fx="http://javafx.com/fxml/1"
    fx:controller="test.TableTestController">
    <center>
        <TabPane fx:id="TabPane">
            <tabs>
                <Tab fx:id="AllPosts" closable="false" text="All Posts">
                    <content>
                        <fx:include fx:id="TAllPosts"
                            source="TestTableView.fxml" />
                    </content>
                </Tab>
            </tabs>
        </TabPane>
    </center>
</BorderPane>

Answer 1

您可以简单地在 TableView2 的控制器中进行初始化。还要在控制器中添加 AllPosts 而不是 fxml：

public class TableView2Controller {

    @FXML private Tab AllPosts;

    @FXML
    public void initialize() throws IOException {

      FXMLLoader loader = new FXMLLoader(getClass().getResource("TestTableView.fxml"));
      Pane pane = loader.load();
      TableTestController controller = loader.getController();
      controller.initializeModel();
      AllPosts.setContent(pane);
   }
}

Answer 2

多亏了 Slaw、Fabian 和 James_D 的建议，再加上几个小时的网上教程，我现在已经解决了这个问题。

我不得不使用嵌套控制器。
子 fxml 的名称应与主 fxml 中定义为 fx:id 的名称相匹配。这如果我们以与子 fxml 名称相同的格式指定它，但在末尾添加 Controller 并将首字母小写，则子 fxml 的控制器将自动注入。请参阅下面我更新的工作代码。

我的TestTableView.fxml是-

<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.TableColumn?>
<?import javafx.scene.control.TableView?>
<?import javafx.scene.control.cell.PropertyValueFactory?>
<?import javafx.scene.layout.AnchorPane?>

<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity"
    minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0"
    prefWidth="600.0" xmlns="http://javafx.com/javafx/11.0.1"
    xmlns:fx="http://javafx.com/fxml/1"
    fx:id ="t_anch"
    fx:controller="test.TestTableViewController">

    <children>
        <TableView fx:id="t_posts" layoutX="14.0" layoutY="65.0"
            prefHeight="141.0" prefWidth="570.0">
            <columns>
                <TableColumn fx:id="c_post_id" prefWidth="78.0"
                    text="Post Id" />
                <TableColumn fx:id="c_post_title" prefWidth="135.0"
                    text="Post Title" />
                <TableColumn fx:id="c_post_desc" prefWidth="237.0"
                    text="Post Desc" />
                <TableColumn fx:id="c_post_creator" prefWidth="119.0"
                    text="Post Creator" />
            </columns>
        </TableView>
    </children>
</AnchorPane>

我的TestTableView2.fxml是-

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

<?import javafx.scene.control.Tab?>
<?import javafx.scene.control.TabPane?>
<?import javafx.scene.layout.BorderPane?>

<BorderPane maxHeight="-Infinity" maxWidth="-Infinity"
    minHeight="-Infinity" minWidth="-Infinity" prefHeight="515.0"
    prefWidth="714.0" xmlns="http://javafx.com/javafx/11.0.1"
    xmlns:fx="http://javafx.com/fxml/1"
    fx:controller="test.TestTableView2Controller">
    <center>
        <TabPane>
            <tabs>
                <Tab closable="false" text="All Posts">
                    <content>
                            <fx:include fx:id="testTableView"
                                source="TestTableView.fxml" />
                    </content>
                </Tab>
            </tabs>
        </TabPane>
    </center>
</BorderPane>

测试表视图控制器

package test;

import javafx.collections.ObservableList;
import javafx.fxml.FXML;
import javafx.scene.Parent;
import javafx.scene.control.Tab;
import javafx.scene.control.TabPane;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.layout.AnchorPane;
import model.app.posts.TablePost;

public class TestTableViewController {

    @FXML private  TableView<TablePost> t_posts ;
    @FXML private  TableColumn<TablePost, String> c_post_id ;
    @FXML private  TableColumn<TablePost, String> c_post_title ;
    @FXML private  TableColumn<TablePost, String> c_post_desc ;
    @FXML private  TableColumn<TablePost, String> c_post_creator ;

    @FXML private TabPane TabPane;
    @FXML private Tab AllPosts;
    @FXML private AnchorPane t_anch;
    @FXML private TestTableViewController t_anchController;

    @FXML private Parent TAllPosts;

    @FXML
    public void initialize() {
        System.out.println("Starting Table Init");
        c_post_id.setCellValueFactory(new PropertyValueFactory<TablePost, String>("postId"));
        c_post_title.setCellValueFactory(new PropertyValueFactory<TablePost, String>("postTitle"));
        c_post_desc.setCellValueFactory(new PropertyValueFactory<TablePost, String>("postDesc"));
        c_post_creator.setCellValueFactory(new PropertyValueFactory<TablePost, String>("postCreator"));
        System.out.println("Finished Table Init");
   }

    public void setTableItems(ObservableList<TablePost> posts) {
        t_posts.setItems(posts);
    }

}

TestTableView2Controller

package test;

import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.fxml.FXML;
import model.app.posts.TablePost;

public class TestTableView2Controller {

    @FXML private TestTableViewController testTableViewController;

    @FXML private void initialize() {
        ObservableList<TablePost> posts = FXCollections.observableArrayList();
        TablePost p1 ;
        p1 = new TablePost("id5","title1","desc1","creator1","OPEN");
        posts.add(p1);
        p1 = new TablePost("id6","title2","desc2","creator2","CLOSED");
        posts.add(p1);
        testTableViewController.setTableItems(posts);

    }

}

最后 TableTest.java

package test;

import java.io.IOException;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class TableTest extends Application {

    public TableTest() {
        // TODO Auto-generated constructor stub
    }

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

    @Override
    public void start(Stage stage) throws Exception {
        try {
            // load the fxml file
            FXMLLoader tableloader = new FXMLLoader(getClass().getResource("TestTableView2.fxml"));
            Parent root = tableloader.load();

            //load the login scene
            Scene scene = new Scene(root, 800, 400);
            stage.setTitle("Test Table Screen");
            stage.setScene(scene);
            stage.show();

        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

JavaFX Embedded Table FXML 给出空指针异常

JavaFX Embedded Table FXML giving Null Pointer Exception

javafx

tableview

fxml