我知道很多次都会问这个问题,但我找不到适用于我的解决方案(实际上我甚至无法看到我做错了什么)。
基本思想是在需要时加载GUI组件。因此,我在各种FXML文件中构建了GUI,并实现了控制器类。两者 - FXML文件和类 - 都存储在同一个包中,但是每个组件都是一个包。只要我没有在FXML文件(fx:controller)中定义控制器类,每个FXML文件都会加载并添加到GUI中。如果定义了,我将得到一个LoadException。
为了更好地理解这里是我的代码(简化):
Main.java:
package application;
import application.a.ControllerA;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;
public class Main extends Application
{
// Button aus MainLayout.fxml
@FXML
private Button button;
@Override
public void start(Stage primaryStage)
{
try
{
BorderPane root = new BorderPane();
Parent contentMain = FXMLLoader.load(getClass().getResource("MainLayout.fxml"));
ControllerA contentA = new ControllerA(root);
root.setTop(contentA.getContent());
root.setCenter(contentMain);
Scene scene = new Scene(root, 400, 400);
scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
primaryStage.setScene(scene);
primaryStage.show();
}
catch (Exception e)
{
e.printStackTrace();
}
}
public static void main(String[] args)
{
launch(args);
}
// Event-Handler für den Button -> funktioniert!
@FXML
public void buttonClicked(ActionEvent e)
{
if (!button.getText().equals("NEW"))
{
button.setText("NEW");
}
else
{
button.setText("OLD");
}
}
}
此类也是以下布局的控制器(到目前为止它的工作方式):
MainLayout.fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.layout.GridPane?>
<Pane xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.Main">
<children>
<Button fx:id="button" mnemonicParsing="false" onAction="#buttonClicked" text="Button" />
</children>
</Pane>
在application
的子包(称为a)中,您会发现:
ControllerA.java:
package application.a;
import java.net.URL;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;
public class ControllerA
{
private Parent content;
@FXML
private Button buttonA;
public ControllerA(BorderPane root)
{
String sceneFile = "A.fxml";
URL url = null;
try
{
url = getClass().getResource(sceneFile);
content = FXMLLoader.load(url);
}
catch (Exception ex)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public Parent getContent()
{
return content;
}
@FXML
public void clickedA(ActionEvent e)
{
buttonA.setText("Clicked already");
}
}
A.fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.layout.GridPane?>
<Pane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.a.ControllerA">
<children>
<Button fx:id="buttonA" layoutX="274.0" layoutY="188.0" mnemonicParsing="false" onAction="#clickedA" text="A" />
</children>
</Pane>
这就是,一切都出错了:
javafx.fxml.LoadException:
/Z:/BachelorArbeit/Projektdateien/Entwicklung/EclipseWorkspace/Sandbox/bin/application/a/A.fxml:8
at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2601)
at javafx.fxml.FXMLLoader.access$700(FXMLLoader.java:103)
at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:932)
at javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:971)
at javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:220)
at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:744)
at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2707)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2527)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3214)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
at application.a.ControllerA.<init>(ControllerA.java:26)
at application.Main.start(Main.java:35)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.InstantiationException: application.a.ControllerA
at java.lang.Class.newInstance(Class.java:427)
at sun.reflect.misc.ReflectUtil.newInstance(ReflectUtil.java:51)
at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:927)
... 23 more
Caused by: java.lang.NoSuchMethodException: application.a.ControllerA.<init>()
at java.lang.Class.getConstructor0(Class.java:3082)
at java.lang.Class.newInstance(Class.java:412)
... 25 more
我试图摆弄像
这样的路径字符串但没有任何效果。如果有人可以解决这个问题,我会很放心。
答案 0 :(得分:0)
我将向您展示一个最小的工作示例项目,我建议您根据它调整结构。
文件夹结构如下
这是主要课程 package dynamic.content.javafx;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;
public final class Main extends Application {
@Override
public void start(Stage stage) throws Exception {
Parent root = FXMLLoader.load(getClass().getResource("main.fxml"));
Scene scene = new Scene(root, 300, 200);
stage.setTitle("FXML Welcome");
stage.setScene(scene);
stage.show();
}
public static void main(String[] args) {
launch(args);
}
}
主控制器
package dynamic.content.javafx;
import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Parent;
import javafx.scene.control.Button;
import javafx.scene.layout.AnchorPane;
public final class MainController implements Initializable{
@FXML
private Button btnSwitch;
@FXML
private AnchorPane contentPane;
@Override
public void initialize(URL location, ResourceBundle resources) {
// TODO Auto-generated method stub
}
private boolean swtch = false;
@FXML
public void handleContentSwitch() throws IOException{
Parent contentNode = null;
if(swtch){
System.out.println("loading content A");
contentNode = FXMLLoader.load(getClass().getResource("./content/content_a.fxml"));
}else{
System.out.println("loading content B");
contentNode = FXMLLoader.load(getClass().getResource("./content/content_b.fxml"));
}
contentPane.getChildren().clear();
contentPane.getChildren().add(contentNode);
swtch = !swtch;
}
}
主要FXML
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<VBox alignment="TOP_CENTER" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="200.0" prefWidth="300.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="dynamic.content.javafx.MainController">
<children>
<Button fx:id="btnSwitch" onAction="#handleContentSwitch" alignment="CENTER" contentDisplay="CENTER" mnemonicParsing="false" text="Switch Content" />
<AnchorPane fx:id="contentPane" prefHeight="150.0" prefWidth="300.0" />
</children>
</VBox>
假设我们有内容A和B,我们需要创建一个控制器和FXML每个人
package dynamic.content.javafx.content;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.Initializable;
import javafx.fxml.FXML;
import javafx.scene.control.Label;
public class ContentAController implements Initializable{
@FXML
private Label labl;
@Override
public void initialize(URL location, ResourceBundle resources) {
labl.setText("Content A");
}
}
现在相应的FXML
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="150.0" prefWidth="300.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="dynamic.content.javafx.content.ContentAController">
<children>
<Label fx:id="labl" alignment="CENTER" contentDisplay="CENTER" text="Label" textAlignment="CENTER" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0" />
</children>
</AnchorPane>
以下是第二个控制器
package dynamic.content.javafx.content;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
public class ContentBController implements Initializable{
@FXML
private Label labl;
@Override
public void initialize(URL location, ResourceBundle resources) {
labl.setText("Content B");
}
}
和第二个FXML
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="150.0" prefWidth="300.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="dynamic.content.javafx.content.ContentBController">
<children>
<Label fx:id="labl" alignment="CENTER" contentDisplay="CENTER" text="Label" textAlignment="CENTER" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0" />
</children>
</AnchorPane>
如果您知道按下按钮,将动态加载内容
如果您有任何疑问,请告诉我: - )
答案 1 :(得分:0)
您正在使用两种不同的方式使用FXML和控制器。如果您的FXML文件有fx:controller="SomeClass"
,那么FXMLLoader
将实例化该类并将该实例用作控制器:换句话说,它使FXML创建控制器。
另一方面,控制器的构造函数加载FXML,因此您还可以让控制器创建FXML中定义的UI。
异常的原因是当FXMLLoader
遇到fx:controller
属性时,它会调用指定类的无参数构造函数:即在这种情况下它试图致电new ControllerA()
。由于没有这样的构造函数,您将获得异常:
java.lang.NoSuchMethodException: application.a.ControllerA.<init>()
对于控制器构造函数的BorderPane
参数的用途是什么并不是很清楚,因为你从不使用它。但是,即使你在这里有一个合适的构造函数,也会引起另一个问题:加载FXML会调用控制器的构造函数,它会加载FXML,它将调用控制器的构造函数等:你会得到一个StackOverflowException
。如果要从控制器的构造函数加载FXML:
fx:controller
属性将FXMLLoader
上的控制器显式设置为当前控制器实例:
public ControllerA(BorderPane root)
{
String sceneFile = "A.fxml";
URL url = null;
try
{
url = getClass().getResource(sceneFile);
FXMLLoader loader = new FXMLLoader(url);
loader.setController(this);
content = loader.load();
}
catch (Exception ex)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}