方法一:

public class HomeFragment extends Fragment {

    private View mRootView;
    private Toolbar mToolbar;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment

        mRootView = inflater.inflate(R.layout.fragment_home, container, false);
        return mRootView;
    }


    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        
        mToolbar = mRootView.findViewById(R.id.toolbar);
        mToolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(getContext(), "Navigation Clicked", Toast.LENGTH_LONG).show();
            }
        });
    }
}

方法二:

public class HomeFragment extends Fragment {

    private Toolbar mToolbar;

    public HomeFragment() {
        // Required empty public constructor

    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_home, container, false);
    }


    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        
        mToolbar = getActivity().findViewById(R.id.toolbar);
        mToolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(getContext(), "Navigation Clicked", Toast.LENGTH_LONG).show();
            }
        });
    }
}