android之利用RadioGroup切换fragment

activity中：
RadioGroup gh;
FragmentManager fm;
FragmentTransaction ft;

gh = (RadioGroup) this.findViewById(R.id.grouphead);
fm = getSupportFragmentManager();

 	gh.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
       		@Override
       		public void onCheckedChanged(RadioGroup radioGroup, int i) {
				ft = fm.beginTransaction();
                if(libF != null)ft.hide(libF);
                if(dynamicF != null)ft.hide(dynamicF);
                if(mineF != null)ft.hide(mineF);
                if(recommendF != null)ft.hide(recommendF);
                if(i == R.id.libBtn){
                    if(libF == null){
                        libF = new libFragment();
                        ft.add(R.id.lay,libF,"lib_");
                    }
                    ft.show(libF);
                }else if(i == R.id.dynamicBtn){
                    if(dynamicF == null){
                        dynamicF = new dynamicFragment();
                        ft.add(R.id.lay,dynamicF,"dynamic_");
                    }
                    ft.show(dynamicF);
                }else if(i == R.id.recommendBtn){
                    if(recommendF == null){
                        recommendF = new recommendFragment();
                        ft.add(R.id.lay,recommendF,"recommend_");
                    }
                    ft.show(recommendF);
                }else if(i == R.id.mineBtn){
                    if(mineF == null){
                        mineF = new mineFragment();
                        ft.add(R.id.lay,mineF,"mine_");
                    }
                    ft.show(mineF);
                }
                ft.commit();
            }
        });

以其中一个fragment为例：

import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.fragment.app.Fragment;


/**
 * A simple {@link Fragment} subclass.
 * Activities that contain this fragment must implement the
 * {@link dynamicFragment.OnFragmentInteractionListener} interface
 * to handle interaction events.
 * Use the {@link dynamicFragment#newInstance} factory method to
 * create an instance of this fragment.
 */
public class dynamicFragment extends Fragment {
    // TODO: Rename parameter arguments, choose names that match
    // the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";

    // TODO: Rename and change types of parameters
    private String mParam1;
    private String mParam2;

    private OnFragmentInteractionListener mListener;

    public dynamicFragment() {
        // Required empty public constructor
    }

    /**
     * Use this factory method to create a new instance of
     * this fragment using the provided parameters.
     *
     * @param param1 Parameter 1.
     * @param param2 Parameter 2.
     * @return A new instance of fragment dynamicFragment.
     */
    // TODO: Rename and change types and number of parameters
    public static dynamicFragment newInstance(String param1, String param2) {
        dynamicFragment fragment = new dynamicFragment();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

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

    // TODO: Rename method, update argument and hook method into UI event
    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onFragmentInteraction(uri);
        }
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof OnFragmentInteractionListener) {
            mListener = (OnFragmentInteractionListener) context;
        } else {
            throw new RuntimeException(context.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    /**
     * This interface must be implemented by activities that contain this
     * fragment to allow an interaction in this fragment to be communicated
     * to the activity and potentially other fragments contained in that
     * activity.
     * <p>
     * See the Android Training lesson <a href=
     * "http://developer.android.com/training/basics/fragments/communicating.html"
     * >Communicating with Other Fragments</a> for more information.
     */
    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        void onFragmentInteraction(Uri uri);
    }
}

页面效果：