JavaFX时钟小部件随机抛出异常
我已经编写了一个扩展JavaFX的JavaFX时钟小部件随机抛出异常,java,eclipse,javafx,time-format,Java,Eclipse,Javafx,Time Format,我已经编写了一个扩展JavaFX的Text类的小时钟小部件。为了更新时间,我正在使用一个任务,该任务基本上将文本设置为当前系统时间。当我在Eclipse中运行这个应用程序时,它有时会在我调用stage.show()的行中抛出NullpointerException 这就是我的widgets源代码的样子: package clock; import java.time.LocalDateTime; import java.time.format.DateTimeFormatter; impor
Text
类的小时钟小部件。为了更新时间,我正在使用一个任务,该任务基本上将文本设置为当前系统时间。当我在Eclipse中运行这个应用程序时,它有时会在我调用stage.show()
的行中抛出NullpointerException
这就是我的widgets源代码的样子:
package clock;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import javafx.concurrent.Task;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
public class CurrentClockText extends Text {
private final DateTimeFormatter formatter;
public static final int HOUR = 1;
public static final int HOUR_MINUTE = 2;
public static final int HOUR_MINUTE_SECOND = 3;
public static final int HOUR_MINUTE_SECOND_MILLISECOND = 4;
private final long updateInterval;
private final Task<Void> updater = new Task<Void>() {
@Override
protected Void call() throws Exception {
while (true) {
LocalDateTime now = LocalDateTime.now();
String nowTextual = formatter.format(now);
setText(nowTextual);
try {
Thread.sleep(updateInterval);
} catch (InterruptedException ignore) {
}
}
}
};
public CurrentClockText() {
this(HOUR_MINUTE);
}
public CurrentClockText(final int detailLevel) {
String timeFormat = "";
switch (detailLevel) {
case HOUR:
timeFormat = "HH";
updateInterval = 60000;
break;
case HOUR_MINUTE:
timeFormat = "HH:mm";
updateInterval = 15000;
break;
case HOUR_MINUTE_SECOND:
timeFormat = "HH:mm:ss";
updateInterval = 500;
break;
case HOUR_MINUTE_SECOND_MILLISECOND:
updateInterval = 1;
timeFormat = "HH:mm:ss.S";
break;
default:
throw new IllegalArgumentException(
"Unknown detail level for Clock: " + detailLevel);
}
setFont(new Font("Verdana", 28));
formatter = DateTimeFormatter.ofPattern(timeFormat);
Thread updaterThread = new Thread(updater, "CurrentClockText.updaterThread");
updaterThread.setDaemon(true);
updaterThread.start();
}
}
这是stacktrace:
Exception in Application start method
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(Unknown Source)
at com.sun.javafx.application.LauncherImpl.launchApplication(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at sun.launcher.LauncherHelper$FXHelper.main(Unknown Source)
Caused by: java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(Unknown Source)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$152(Unknown Source)
at com.sun.javafx.application.LauncherImpl$$Lambda$50/14845382.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
at com.sun.javafx.text.PrismTextLayout.addTextRun(Unknown Source)
at com.sun.javafx.text.GlyphLayout.addTextRun(Unknown Source)
at com.sun.javafx.text.GlyphLayout.breakRuns(Unknown Source)
at com.sun.javafx.text.PrismTextLayout.buildRuns(Unknown Source)
at com.sun.javafx.text.PrismTextLayout.layout(Unknown Source)
at com.sun.javafx.text.PrismTextLayout.ensureLayout(Unknown Source)
at com.sun.javafx.text.PrismTextLayout.getBounds(Unknown Source)
at javafx.scene.text.Text.getLogicalBounds(Unknown Source)
at javafx.scene.text.Text.impl_computeLayoutBounds(Unknown Source)
at javafx.scene.Node$12.computeBounds(Unknown Source)
at javafx.scene.Node$LazyBoundsProperty.get(Unknown Source)
at javafx.scene.Node$LazyBoundsProperty.get(Unknown Source)
at javafx.scene.Node.getLayoutBounds(Unknown Source)
at javafx.scene.Node.prefWidth(Unknown Source)
at javafx.scene.Node.minWidth(Unknown Source)
at javafx.scene.layout.Region.computeChildPrefAreaWidth(Unknown Source)
at javafx.scene.layout.BorderPane.getAreaWidth(Unknown Source)
at javafx.scene.layout.BorderPane.computePrefWidth(Unknown Source)
at javafx.scene.Parent.prefWidth(Unknown Source)
at javafx.scene.layout.Region.prefWidth(Unknown Source)
at javafx.scene.Scene.getPreferredWidth(Unknown Source)
at javafx.scene.Scene.resizeRootToPreferredSize(Unknown Source)
at javafx.scene.Scene.preferredSize(Unknown Source)
at javafx.scene.Scene.impl_preferredSize(Unknown Source)
at javafx.stage.Window$9.invalidated(Unknown Source)
at javafx.beans.property.BooleanPropertyBase.markInvalid(Unknown Source)
at javafx.beans.property.BooleanPropertyBase.set(Unknown Source)
at javafx.stage.Window.setShowing(Unknown Source)
at javafx.stage.Window.show(Unknown Source)
at javafx.stage.Stage.show(Unknown Source)
at clock.Boot.start(Boot.java:19)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$159(Unknown Source)
at com.sun.javafx.application.LauncherImpl$$Lambda$53/19600960.run(Unknown Source)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$172(Unknown Source)
at com.sun.javafx.application.PlatformImpl$$Lambda$45/18503843.run(Unknown Source)
at com.sun.javafx.application.PlatformImpl.lambda$null$170(Unknown Source)
at com.sun.javafx.application.PlatformImpl$$Lambda$48/27167109.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$171(Unknown Source)
at com.sun.javafx.application.PlatformImpl$$Lambda$47/2180324.run(Unknown Source)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(Unknown Source)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$145(Unknown Source)
at com.sun.glass.ui.win.WinApplication$$Lambda$36/3326003.run(Unknown Source)
... 1 more
Exception running application clock.Boot
正如我所说的,这种异常只发生在一些运行中,并不总是发生。它主要发生在我更改
detailLevel=4的格式模式时,但在再次更改后仍会继续运行。我猜这实际上可能与Eclipse有关,但我也无法调试代码,因为异常在阶段抛出。show
调用我完全不理解。这个随机异常的原因是什么?我如何修复它?在JavaFX中,与大多数其他GUI工具包一样,有一个特定的线程处理所有与UI相关的操作。应用程序不得在此线程之外更新UI。如果需要从另一个线程更新UI,通常会有API可用,以确保代码在UI线程的上下文中执行。对于JavaFX,请参阅以了解更多信息
在您的情况下,最简单的解决方案是确保您的setText()
调用在JavaFX应用程序线程上执行,而不是在与任务相关联的线程上执行:
...
Platform.runLater(() -> setText(nowTextual));
...
JavaFX中还有其他API可用于制作动画,可用于在特定的时间间隔调用处理程序方法-这将从循环中删除Thread.sleep()
调用。有关详细信息,请参阅。:[…]您必须确保使用平台。稍后运行
,以便在FX应用程序线程上对场景图进行任何修改。@AndreasFester这似乎已经解决了问题。你能把它贴出来作为答案,这样我就可以把它标记为完成了吗?谢谢我现在这样调用setText
:Platform.runLater(()->setText(nowtext))代码>。然而,这似乎打破了文本的首选宽度。
...
Platform.runLater(() -> setText(nowTextual));
...