如何解決小部件處置異常？

Question

在我看來，當窗口打開時，我有一個選擇監聽器。 （視圖采用所選項目並根據該項目顯示一些數據）。

關閉並重新打開視圖時會發生異常。 在另一個窗口中更改選擇時更新視圖的功能有效但在重新打開視圖后視圖未更新。

我有一個帶有setText方法的標簽，它給我這個小部件處理異常。

這是一個選擇偵聽器問題嗎？ 在處理視圖時，有必要刪除在執行期間創建的所有偵聽器嗎？

編輯：

選擇監聽器代碼：

final ISelectionListener selectionListener=(new ISelectionListener()
    {

        @Override
        public void selectionChanged(IWorkbenchPart part, ISelection selection) {
            // TODO Auto-generated method stub
            IProject project = null ;
            if(selection==null){
                try {
                    throw new ProjectNotSelected("No selection in Window");
                } catch (ProjectNotSelected e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                }
            }
            if(selection instanceof IStructuredSelection) {
                Object element = ((IStructuredSelection)selection).getFirstElement();

                if (element instanceof IResource) {
                    project= ((IResource)element).getProject();

                }
                else if (element instanceof IPackageFragmentRoot) {
                    IJavaProject jProject = ((IPackageFragmentRoot)element).getJavaProject();
                    project = jProject.getProject();
                }
                else if (element instanceof IJavaElement) {
                    IJavaProject jProject= ((IJavaElement)element).getJavaProject();
                    project = jProject.getProject();
                }
                else{

                    try {
                        throw new ProjectNotSelected("case 1");
                    } catch (ProjectNotSelected e1) {
                        // TODO Auto-generated catch block
                        e1.printStackTrace();
                    }

                }

            }
            else{
                try {
                    throw new ProjectNotSelected("case 2");
                } catch (ProjectNotSelected e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                }
            }
            if(project!=null)
            {


                String projectName=project.getName();
                projectNameLabel.setText("Project: "+projectName);



            }
        }
    });

添加選擇偵聽器的函數：

public void newGetCurrentProject(final ISelectionListener selectionListener)
    {   

        IWorkbench workbench = PlatformUI.getWorkbench();

        final IWorkbenchWindow window =workbench.getActiveWorkbenchWindow() ;
        final IPartService pS=window.getPartService();


        pS.addPartListener(new IPartListener()
        {
            @Override
            public void partActivated(IWorkbenchPart part) {
                // TODO Auto-generated method stub              window.getSelectionService().addSelectionListener("org.eclipse.jdt.ui.PackageExplorer",selectionListener);  
            }
            @Override
            public void partBroughtToTop(IWorkbenchPart part) {
                // TODO Auto-generated method stub

            }

            @Override
            public void partClosed(IWorkbenchPart part) {
                // TODO Auto-generated method stub
                                window.getSelectionService().removeSelectionListener("org.eclipse.jdt.ui.PackageExplorer",selectionListener);

            }
        @Override
            public void partDeactivated(IWorkbenchPart part) {
                // TODO Auto-generated method stub


            }

            @Override
            public void partOpened(IWorkbenchPart part) {
                // TODO Auto-generated method stub
                window.getSelectionService().addSelectionListener("org.eclipse.jdt.ui.PackageExplorer",selectionListener);
                }

        });

堆棧跟蹤：

org.eclipse.swt.SWTException: Widget is disposed
    at org.eclipse.swt.SWT.error(SWT.java:4361)
    at org.eclipse.swt.SWT.error(SWT.java:4276)
    at org.eclipse.swt.SWT.error(SWT.java:4247)
    at org.eclipse.swt.widgets.Widget.error(Widget.java:468)
    at org.eclipse.swt.widgets.Widget.checkWidget(Widget.java:340)
    at org.eclipse.swt.widgets.Label.setText(Label.java:386)
    at com.warnings.compilation.views.TabViewer$2.selectionChanged(TabViewer.java:260)
    at org.eclipse.ui.internal.AbstractPartSelectionTracker$1.run(AbstractPartSelectionTracker.java:119)
    at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
    at org.eclipse.core.runtime.Platform.run(Platform.java:857)
    at org.eclipse.ui.internal.AbstractPartSelectionTracker.fireSelection(AbstractPartSelectionTracker.java:117)
    at org.eclipse.ui.internal.WindowPartSelectionTracker$1.selectionChanged(WindowPartSelectionTracker.java:38)
    at org.eclipse.ui.internal.AbstractPartSelectionTracker$1.run(AbstractPartSelectionTracker.java:119)
    at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
    at org.eclipse.core.runtime.Platform.run(Platform.java:857)
    at org.eclipse.ui.internal.AbstractPartSelectionTracker.fireSelection(AbstractPartSelectionTracker.java:117)
    at org.eclipse.ui.internal.PagePartSelectionTracker$1.selectionChanged(PagePartSelectionTracker.java:49)
    at org.eclipse.jface.viewers.Viewer$2.run(Viewer.java:164)
    at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
    at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:49)
    at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:175)
    at org.eclipse.jface.viewers.Viewer.fireSelectionChanged(Viewer.java:162)
    at org.eclipse.jface.viewers.StructuredViewer.updateSelection(StructuredViewer.java:2188)
    at org.eclipse.jface.viewers.StructuredViewer.handleSelect(StructuredViewer.java:1211)
    at org.eclipse.jface.viewers.StructuredViewer$4.widgetSelected(StructuredViewer.java:1241)
    at org.eclipse.jface.util.OpenStrategy.fireSelectionEvent(OpenStrategy.java:239)
    at org.eclipse.jface.util.OpenStrategy.access$4(OpenStrategy.java:233)
    at org.eclipse.jface.util.OpenStrategy$1.handleEvent(OpenStrategy.java:403)
    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:4169)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3758)
    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:124)
    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:353)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:180)
    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 org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:629)
    at org.eclipse.equinox.launcher.Main.basicRun(Main.java:584)
    at org.eclipse.equinox.launcher.Main.run(Main.java:1438)
    at org.eclipse.equinox.launcher.Main.main(Main.java:1414)

選擇偵聽器放在createPartControl中。

問題出現在這一行：

projectNameLabel.setText("Project: "+projectName);

Answer 1

在視圖部件中添加選擇偵聽器時，必須在視圖關閉時刪除偵聽器。 就像是：

public classs MyView extends ViewPart
{
  private ISelectionListener myListener;

  @Override
  public void createPartControl(final Composite parent)
  {
    myListener = .... create listener

    ISelectionService selService = ... get selection serivce

    selService.addSelectionListener(myListener);
  }


  @Override
  public void dispose()
  {
    if (myListener != null)
     {
       ISelectionService selService = ... get selection serivce

       selService.removeSelectionListener(myListener);

       myListener = null;
     }

    super.dispose();
  }
}