PreferencePage的小问题花了大把时间-白红宇

在Eclipse里可以用FieldEditorPreferencePage简化Preference page的创建，但在随机文档里只重点说了要实现createFieldEditors方法，我明明实现了它，但点Preference命令时却总是提示：

java.lang.InstantiationException: org.haree.mobject.ui.BasicPreferencePage

at java.lang.Class.newInstance0(Unknown Source)

at java.lang.Class.newInstance(Unknown Source)

at org.eclipse.core.internal.registry.ConfigurationElement.createExecutableExtension(ConfigurationElement.java:

141

)

at org.eclipse.core.internal.registry.ConfigurationElement.createExecutableExtension(ConfigurationElement.java:

124

)

at org.eclipse.core.internal.registry.ConfigurationElement.createExecutableExtension(ConfigurationElement.java:

113

)

at org.eclipse.ui.internal.WorkbenchPlugin.createExtension(WorkbenchPlugin.java:

189

)

at org.eclipse.ui.internal.dialogs.WorkbenchPreferenceNode.createPage(WorkbenchPreferenceNode.java:

)

at org.eclipse.jface.preference.PreferenceDialog.showPage(PreferenceDialog.java:

985

)

at org.eclipse.jface.preference.PreferenceDialog$

.selectionChanged(PreferenceDialog.java:

529

)

at org.eclipse.jface.viewers.StructuredViewer$

.run(StructuredViewer.java:

450

)

at org.eclipse.core.internal.runtime.InternalPlatform.run(InternalPlatform.java:

616

)

at org.eclipse.core.runtime.Platform.run(Platform.java:

747

)

at org.eclipse.jface.viewers.StructuredViewer.firePostSelectionChanged(StructuredViewer.java:

448

)

at org.eclipse.jface.viewers.StructuredViewer.setSelection(StructuredViewer.java:

1094

)

at org.eclipse.jface.preference.PreferenceDialog.selectSavedItem(PreferenceDialog.java:

807

)

at org.eclipse.jface.preference.PreferenceDialog$

.run(PreferenceDialog.java:

309

)

at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:

)

at org.eclipse.jface.preference.PreferenceDialog.createContents(PreferenceDialog.java:

305

)

at org.eclipse.jface.window.Window.create(Window.java:

348

)

at org.eclipse.jface.dialogs.Dialog.create(Dialog.java:

925

)

at org.eclipse.ui.internal.OpenPreferencesAction.run(OpenPreferencesAction.java:

)

at org.eclipse.jface.action.Action.runWithEvent(Action.java:

881

)

at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:

915

)

at org.eclipse.jface.action.ActionContributionItem.access$

(ActionContributionItem.java:

866

)

at org.eclipse.jface.action.ActionContributionItem$

.handleEvent(ActionContributionItem.java:

785

)

at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:

)

at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:

796

)

at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:

2772

)

at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:

2431

)

找了一个多小时，才发现原来是要提供一个没有参数的构造方法才可以。想了一下，可能因为Eclipse最终是使用Class.newInstance()的方式来生成界面元素的，所以有这个要求。

算是一个经验吧，我觉得Eclipse的帮助再丰富些就好了，特别是应该提供更多的例子代码。

顺便推荐下面两篇文章（要是Eclipse帮助都这么详细该多好）：

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