将基于activity的代码移植到基于fragment的页面中

Question

private void initView() {

    expandTabView = (ExpandTabView) findViewById(R.id.expandtab_view);

    viewLeft = new LeftFilterView(this, FilterDataSource.createPriceFilterItems());

    viewMiddle = new MiddleFilterView(this);

    viewRight = new RightFilterView(this, FilterDataSource.createSortFilterItems());

}

上方代码要是移植到fragment页面中需要修改什么？
我改成了这样，但是运行时调用view的时候出现了空指针
private void initView() {

    expandTabView = (ExpandTabView) getActivity().findViewById(R.id.expandtab_view);

    viewLeft = new LeftFilterView(getActivity(), FilterDataSource.createPriceFilterItems());

    viewMiddle = new MiddleFilterView(getActivity());

    viewRight = new RightFilterView(getActivity(), FilterDataSource.createSortFilterItems());

}