问题描述
我未实现的目标:用户从 DatePicker 中选择日期后,该日期将作为选项转发到 ComboBox。
示例.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.ComboBox?>
<?import javafx.scene.control.DatePicker?>
<?import javafx.scene.layout.borderpane?>
<borderpane prefheight="259.0" prefWidth="351.0" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="Controller">
<center>
<ComboBox fx:id="myBox" prefWidth="150.0" borderpane.alignment="CENTER" />
</center>
<bottom>
<DatePicker fx:id="myDatePicker" onAction="#getDatePicked" borderpane.alignment="CENTER" />
</bottom>
</borderpane>
Controller.java
public class Controller {
@FXML
// private SearchableComboBox<String> myBox;
//
// public SearchableComboBox<String> getMyBox() {
// return myBox;
// }
private DatePicker myDatePicker;
public DatePicker getMyDatePicker() {
return myDatePicker;
}
private ComboBox<String> myBox;
public ComboBox<String> getMyBox() {
return myBox;
}
public void initialize() {
// ObservableList<String> defaultTicker = FXCollections.observableArrayList("Something");
// myBox.getItems().addAll(defaultTicker);
}
private LocalDate datePicked;
public LocalDate getDatePickedAction(ActionEvent event) {
return getDatePicked();
}
public LocalDate getDatePicked() {
return datePicked;
}
public void setDatePicked(DatePicker myDatePicker) {
this.datePicked = myDatePicker.getValue();
}
}
UserInterface.java
public class UserInterface extends Application {
@Override
public void start(Stage primaryStage) {
try {
FXMLLoader loader = new FXMLLoader(getClass().getResource("Sample.fxml"));
Parent root = loader.load();
Controller controller = loader.getController();
primaryStage.setTitle("Title");
primaryStage.setScene(new Scene(root));
primaryStage.show();
// ObservableList<String> toAdd = FXCollections.observableArrayList("a","b","c");
// controller.getMyBox().getItems().addAll(toAdd);
controller.getMyDatePicker().setonAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
controller.setDatePicked(controller.getMyDatePicker());
System.out.println(controller.getDatePicked());
}
});
List<String> addStuff = new ArrayList<String>();
addStuff.add(controller.getDatePicked().toString());
controller.getMyBox().getItems().addAll(addStuff);
} catch (Exception e) {
e.printstacktrace();
}
}
public static void main(String[] args) {
launch(args);
}
}
从这里开始,有两种情况:
- 如果在类控制器中:
public void initialize() {
ObservableList<String> defaultTicker = FXCollections.observableArrayList("Something");
myBox.getItems().addAll(defaultTicker);
}
javafx.fxml.LoadException:
/D:/Eclipse_stuff/projects/BTL-OOP-20201/Test%20ComboBox/bin/Sample.fxml
at javafx.fxml/javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2707)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2677)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
at javafx.fxml/javafx.fxml.FXMLLoader.load(FXMLLoader.java:2517)
at UserInterface.start(UserInterface.java:17)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:846)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:455)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:428)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:427)
at javafx.graphics/com.sun.glass.ui.invokelaterdispatcher$Future.run(invokelaterdispatcher.java:96)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: java.lang.reflect.InvocationTargetException
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javafx.reflect.Trampoline.invoke(MethodUtil.java:76)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at javafx.base/com.sun.javafx.reflect.MethodUtil.invoke(MethodUtil.java:273)
at javafx.fxml/com.sun.javafx.fxml.MethodHelper.invoke(MethodHelper.java:83)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2673)
... 12 more
Caused by: java.lang.NullPointerException: Cannot invoke "javafx.scene.control.ComboBox.getItems()" because "this.myBox" is null
at Controller.initialize(Controller.java:31)
... 24 more
- 如果保留上面写的代码。 (初始化()为空)
当我尝试将 ComBoBox 设置为在选择日期后调用时,显示相同的输出。
java.lang.NullPointerException: Cannot invoke "java.time.LocalDate.toString()" because the return value of "Controller.getDatePicked()" is null
at UserInterface.start(UserInterface.java:36)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:846)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:455)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:428)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:427)
at javafx.graphics/com.sun.glass.ui.invokelaterdispatcher$Future.run(invokelaterdispatcher.java:96)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
at java.base/java.lang.Thread.run(Thread.java:832)
好吧,先谢谢了,如果有人可以帮助我。
解决方法
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