如何解决带有警报 showAndWait 的应用程序启动方法中的异常
我正在自己学习 JavaFX。我在论坛里搜索过,但我一直找不到类似的问题。
我正在尝试获取关闭确认警报的按钮类型:
package sample;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Group;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Alert;
import javafx.scene.control.ButtonType;
import javafx.stage.Stage;
public class Main extends Application {
@Override
public void start(Stage primaryStage) throws Exception{
Group g = new Group();
Scene scene = new Scene(g,400,400);
primaryStage.setTitle("Hello World");
primaryStage.show();
primaryStage.setScene(scene);
Alert a = new Alert(Alert.AlertType.CONFIRMATION);
a.initOwner(primaryStage);
a.setTitle("alert");
a.setHeaderText("entête");
a.setContentText("hi");
a.show();
a.showAndWait().ifPresent(response -> {
if (response == ButtonType.OK) {
System.out.println("rrrr");
}
});
}
public static void main(String[] args) {
launch(args);
}
}
但我有这个例外,我不知道为什么:
Exception in Application start method
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 javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:464)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:363)
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 java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1071)
Caused by: java.lang.RuntimeException: Exception in Application start method
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:900)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:195)
at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: java.lang.IllegalStateException: Stage already visible
at javafx.graphics/javafx.stage.Stage.showAndWait(Stage.java:451)
at javafx.controls/javafx.scene.control.HeavyweightDialog.showAndWait(HeavyweightDialog.java:162)
at javafx.controls/javafx.scene.control.Dialog.showAndWait(Dialog.java:346)
at sample.Main.start(Main.java:29)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$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)
... 1 more
Exception running application sample.Main
Process finished with exit code 1
我按照本教程的“JavaFX 和 IntelliJ”部分设置了我的 IDE:https://openjfx.io/openjfx-docs/
解决方法
此问题是由于您尝试在已经可见的舞台上调用 showAndWait()
引起的。从javadocs
抛出:
IllegalStateException
- 如果此阶段已经显示。
如果您删除初始调用 a.show();
,这应该可以解决您的问题。
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