我使用Javfx和Fxml文件来执行应用程序。 我想用控制器中的变量数据初始化Textfield，但是我有一个错误：
Exception in Application start method
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$155(LauncherImpl.java:182)
at java.lang.Thread.run(Thread.java:748)
Caused by: javafx.fxml.LoadException:
/C:/Users/Romain/Desktop/DroneKit/out/production/DroneKit/sample/sample.fxml:132
at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2601)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2579)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3214)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
at sample.Main.start(Main.java:23)
at com.sun.javafx.application.LauncherImpl.lambda$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)
... 1 more
Caused by: java.lang.IllegalArgumentException: Can not set java.awt.TextField field sample.Controller.Vitesse to javafx.scene.control.TextField
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171)
at sun.reflect.UnsafeObjectFieldAccessorImpl.set(UnsafeObjectFieldAccessorImpl.java:81)
at java.lang.reflect.Field.set(Field.java:764)
at javafx.fxml.FXMLLoader.injectFields(FXMLLoader.java:1163)
at javafx.fxml.FXMLLoader.access$1600(FXMLLoader.java:103)
at javafx.fxml.FXMLLoader$ValueElement.processValue(FXMLLoader.java:857)
at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:751)
at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2707)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2527)
... 17 more
Exception running application sample.Main
对于该错误，我使用了3个文件：
我的主文件：
package sample;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class Main extends Application {
private Stage m_primaryStage;
@Override
public void start(Stage primaryStage) throws Exception{
Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
m_primaryStage=primaryStage;
m_primaryStage.setTitle("Drone Plane");
m_primaryStage.setScene(new Scene(root));
m_primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
我的控制器：
package sample;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.Node;
import javafx.scene.input.MouseEvent;
import java.awt.*;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.ResourceBundle;
public class Controller implements Initializable, MapComponentInitializedListener {
private int VitesseRef;
private double HauteurRef;
@FXML
private TextField Vitesse;
@FXML
private TextField Hauteur;
{...}
public Controller(){
Point = new ArrayList<Cordonnée>();
try {
python = new DroneJava();
} catch (IOException e) {
e.printStackTrace();
}
VitesseRef=3;
HauteurRef=2.5;
Vitesse = new TextField();
Hauteur = new TextField();
Vitesse.setText(String.valueOf(VitesseRef));
Hauteur.setText(String.valueOf(HauteurRef));
}
和我的Fxml文件：
{...}
<GridPane prefHeight="100.0" prefWidth="600.0" AnchorPane.leftAnchor="10.0" AnchorPane.topAnchor="15.0">
<columnConstraints>
<ColumnConstraints hgrow="SOMETIMES" maxWidth="295.0" minWidth="10.0" prefWidth="68.0" />
<ColumnConstraints hgrow="SOMETIMES" maxWidth="532.0" minWidth="10.0" prefWidth="532.0" />
</columnConstraints>
<rowConstraints>
<RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
<RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
</rowConstraints>
<children>
<Label text="Vitesse :" />
<Label text="Hauteur :" GridPane.rowIndex="1" />
<TextField fx:id="Vitesse" GridPane.columnIndex="1" />
<TextField fx:id="Hauteur" GridPane.columnIndex="1" GridPane.rowIndex="1" />
</children>
</GridPane>
{...}
如果我没有在控制器的构造器中初始化两个Textfield； 执行将在Vitesse.setText。上返回NullPointer异常。 所以有人知道如何使用变量初始化Textfield吗？