javafx - JavaFX 嵌入式表 FXML 给出空指针异常
问题描述
我正在尝试通过参考 YT 的一些教程来创建表格视图。当我做一个简单的表格视图及其相关控制器时,它就可以工作。
主类:
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();
}
}
}
控制器类:
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;
}
}
测试表视图.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,我将这个 fxml 注入到一个选项卡视图中,我得到了 NPE。即,如果我在 Main 类中更改我的第 28 行以引用新的基于 Tab 的 fxml,它会失败
这有效: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>
解决方案
感谢 Slaw、Fabian 和 James_D 的建议以及几个小时的互联网教程,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 的名称匹配。如果我们以与子 fxml 名称相同的格式指定子 fxml 的控制器,但在末尾添加 Controller 并使首字母小写,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);
}
}
测试表视图2控制器
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);
}
}
最后是 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();
}
}
}
推荐阅读
- python - Thonny 可以在 Raspberry Pi 上以 root 身份运行脚本吗?
- tensorflow - SSD_ResNet50_v1_FPN 到底是什么?
- javascript - React - How to specify an icon in an object as a value
- java - 使用 Streams 和 StreamSupplier:forEach 关闭 StreamSupplier 而不是流的实例
- linux - 填充变量时,Bashscript 引发命令错误
- c# - 使用自定义响应类处理 .NET5 中的错误
- javascript - 从本地模块在特定网页上运行 jquery 代码片段
- ms-access - 将带有富文本的 MS Access 365 报告导出为 Word 条带格式以及所有框等 -
- javascript - 通过变量 PHP 传递数据时 jw 播放器不起作用
- python - Python3 脚本在控制台中运行良好,但在由 crontab 执行时无法运行