xtextDocument.modify(new IUnitOfWork<Void, XtextResource>() {

			@Override
			public java.lang.Void exec(XtextResource res) throws Exception {
				//do something with res
// e.g.
//Model m = (Model) resource.getContents().get(0);
//or
// res.getContents().set(0, MyDslFactory.eINSTANCE.createModel());
				return null;
			}
		}
			);

@Override
protected void pageChange(int newPageIndex) {
	IEditorInput input = getEditorInput();
	if (input instanceof FileEditorInput) {
		FileEditorInput fInput = (FileEditorInput)input;
		Injector injector = new MyDslStandaloneSetup().createInjectorAndDoEMFRegistration();
		XtextResourceSet resourceSet = (injector.getInstance(XtextResourceSet.class));
		resourceSet.addLoadOption(XtextResource.OPTION_RESOLVE_ALL, Boolean.TRUE);
		Resource resource = resourceSet.getResource(URI.createURI(fInput.getURI().toString()), true);
		
		//this method will get the content from resource and display on editor
		resourceTableEditor.refreshContentsWithResource(resource);
		
		//don't know how to deal with it, what i wanna do is to display the content of resource on the editor
		XtextDocument document = (XtextDocument) editor.getDocument();
		document.modify(new IUnitOfWork<Void, XtextResource>() {

			@Override
			public java.lang.Void exec(XtextResource state)
					throws Exception {
				// TODO Auto-generated method stub
				return null;
			}
			
		});
		
		//the only way i found to change text on the editor(XtextEditor)
		editor.getDocumentProvider().getDocument(editor.getEditorInput()).set("add stuff!!");
	}
}