我将使用SWT / jface实现向导。运行程序时，出现以下错误：
Exception in thread "main" java.lang.NullPointerException
at org.eclipse.jface.resource.JFaceResources.getResources(JFaceResources.java:209)
at org.eclipse.jface.resource.JFaceResources.getImageRegistry(JFaceResources.java:402)
at org.eclipse.jface.wizard.Wizard.<init>(Wizard.java:105)
at mypackage.ReservationWizard.<init>(ReservationWizard.java:21)
at mypackage.ReservationWizard.main(ReservationWizard.java:69)
我的代码部分：
public class ReservationWizard extends Wizard {
**public ReservationWizard() {**
// setWindowTitle("Hotel room reservation wizard");
// setNeedsProgressMonitor(true);
// setDefaultPageImageDescriptor(ImageDescriptor.createFromFile(null, "Unknown.jpg"));
}
...
public static void main(String[] args) {
**ReservationWizard wizard = new ReservationWizard();**
WizardDialog dialog = new WizardDialog(Display.getDefault().getActiveShell(), wizard);
dialog.setBlockOnOpen(true);
dialog.open();
}
}
从代码中可以看出，即使ReservationWizard（）为空，它也有一个错误。我该怎么办？
在指定的行上有错误。
编辑：
创建显示时，出现以下错误：
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at org.eclipse.jface.resource.JFaceResources.getFontRegistry(JFaceResources.java:340)
at org.eclipse.jface.window.Window.createShell(Window.java:508)
at org.eclipse.jface.window.Window.create(Window.java:429)
at org.eclipse.jface.dialogs.Dialog.create(Dialog.java:1096)
at org.eclipse.jface.window.Window.open(Window.java:792)
at mypackage.ReservationWizard.main(ReservationWizard.java:76)
Caused by: java.lang.ClassNotFoundException: org.eclipse.core.commands.common.EventManager
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 30 more
最佳答案
调用向导之前，您尚未创建Display。 SWT / JFace应用程序要做的第一件事是创建显示。
因此，您需要：
public static void main(final String [] args)
{
// Create the display
Display display = new Display();
ReservationWizard wizard = new ReservationWizard();
WizardDialog dialog = new WizardDialog(display.getActiveShell(), wizard);
dialog.setBlockOnOpen(true);
dialog.open();
}
关于java - org.eclipse.jface.resource.JFaceResources.getResources上的java.lang.NullPointerException，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/45784350/