please help to explain following method

[rajareddya reddy]

can anybody please how the bolded code set to the addSelectionListener method?I am seeing first time the following mentioned code.I mean the way code is setting to setter.I want to know how this type of code works.

runMapSubMenu .addSelectionListener(new SelectionAdapter() [b]{
			public void widgetSelected(SelectionEvent e) {
				ProjectExplorerView expView = GetViews.getExplorerView();
				if(expView==null)
					new ActionUtil().openViewWithID(IResources.PROJECTEXPLORE_VIEW_ID);
				if(expView.getViewer().getSelection()!=null) {
					ProjectModel selectedElement = (ProjectModel)((IStructuredSelection)expView.getViewer().getSelection()).getFirstElement();
					if(selectedElement.getType().equals(IResources.TYPE_MAP)) {
						new MapFileAction().runMapAction(selectedElement);
					}
				}
			}
		})[/b];

[Rajkamal Pillai]

This is an anonymous inner class. You are defining/declaring an inner class which does not have a name and overriding void widgetSelected(SelectionEvent e) in SelectionAdapter.