java.lang.NullPointerException
    at com.genuitec.eclipse.ast.deploy.core.Deployment.<init>(Unknown Source)
    at com.genuitec.eclipse.ast.deploy.core.ModuleDeployment.<init>(Unknown Source)
    at com.genuitec.eclipse.ast.deploy.core.WebDeployment.<init>(Unknown Source)
    at com.genuitec.eclipse.ast.deploy.core.Deployment.create(Unknown Source)
    at com.genuitec.eclipse.ast.deploy.core.DeploymentManager.loadFromPreferences(Unknown Source)
    at com.genuitec.eclipse.ast.deploy.core.DeploymentManager.init(Unknown Source)
    at com.genuitec.eclipse.ast.deploy.core.DeploymentManager.<init>(Unknown Source)
    at com.genuitec.eclipse.ast.deploy.core.DeploymentManager.getDefault(Unknown Source)
    at com.genuitec.eclipse.ast.deploy.core.ui.ServerTreeViewer$ServerTreeContentProvider.inputChanged(Unknown Source)
    at org.eclipse.jface.viewers.ContentViewer.setInput(ContentViewer.java:276)
    at org.eclipse.jface.viewers.StructuredViewer.setInput(StructuredViewer.java:1690)
    at com.genuitec.eclipse.ast.deploy.core.ui.ServerTreeViewer.<init>(Unknown Source)
    at com.genuitec.eclipse.ast.deploy.core.ui.ServerView.createPartControl(Unknown Source)
    at org.eclipse.ui.internal.ViewReference.createPartHelper(ViewReference.java:375)
    at org.eclipse.ui.internal.ViewReference.createPart(ViewReference.java:229)
    at org.eclipse.ui.internal.WorkbenchPartReference.getPart(WorkbenchPartReference.java:595)
    at org.eclipse.ui.internal.PartPane.setVisible(PartPane.java:313)
    at org.eclipse.ui.internal.ViewPane.setVisible(ViewPane.java:534)
    at org.eclipse.ui.internal.presentations.PresentablePart.setVisible(PresentablePart.java:180)
    at org.eclipse.ui.internal.presentations.util.PresentablePartFolder.select(PresentablePartFolder.java:270)
    at org.eclipse.ui.internal.presentations.util.LeftToRightTabOrder.select(LeftToRightTabOrder.java:65)
    at org.eclipse.ui.internal.presentations.util.TabbedStackPresentation.selectPart(TabbedStackPresentation.java:473)
    at org.eclipse.ui.internal.PartStack.refreshPresentationSelection(PartStack.java:1245)
    at org.eclipse.ui.internal.PartStack.createControl(PartStack.java:662)
    at org.eclipse.ui.internal.PartStack.createControl(PartStack.java:570)
    at org.eclipse.ui.internal.PartSashContainer.createControl(PartSashContainer.java:568)
    at org.eclipse.ui.internal.PerspectiveHelper.activate(PerspectiveHelper.java:272)
    at org.eclipse.ui.internal.Perspective.onActivate(Perspective.java:981)
    at org.eclipse.ui.internal.WorkbenchPage.setPerspective(WorkbenchPage.java:3713)
    at org.eclipse.ui.internal.WorkbenchPage.busySetPerspective(WorkbenchPage.java:1115)
    at org.eclipse.ui.internal.WorkbenchPage.access$16(WorkbenchPage.java:1099)
    at org.eclipse.ui.internal.WorkbenchPage$19.run(WorkbenchPage.java:3814)
    at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
    at org.eclipse.ui.internal.WorkbenchPage.setPerspective(WorkbenchPage.java:3812)
    at org.eclipse.ui.internal.PerspectiveBarContributionItem.select(PerspectiveBarContributionItem.java:124)
    at org.eclipse.ui.internal.PerspectiveBarManager$1.widgetSelected(PerspectiveBarManager.java:129)
    at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:240)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
    at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4165)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3754)
    at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2701)
    at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2665)
    at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2499)
    at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:679)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
    at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:668)
    at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
    at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:123)
    at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:344)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622)
    at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
    at org.eclipse.equinox.launcher.Main.run(Main.java:1410)
    at org.eclipse.equinox.launcher.Main.main(Main.java:1386)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.genuitec.pulse.eclipse.launcher.Main.main(Main.java:110)

這個問題的出現是在啟動myeclipse之後出現的，這時還沒有啟動tomcat，因此可以排除tomcat中專案程式碼問題。應該是myeclipse在初始化工作空間workspace 的時候出的問題。

仔細看下錯誤發現有一條 at com.genuitec.eclipse.ast.deploy.core.Deployment.這個錯誤，於是到工作空間下面的D:\Workspaces\.metadata\.plugins\org.eclipse.core.runtime\.settings目錄下面找到了名稱為at com.genuitec.eclipse.ast.deploy的prefs檔案，開啟檔案一開，哈哈，原來裡面都是原來的一些專案資訊，怪不得會報java.lang.NullPointerException錯誤呢。果斷將此檔案刪除，重啟myeclipse10問題解決