不要OnItemClick工作

Question

我想点击项目，将一个片段替换为另一个片段，并附上详细信息。但是当我点击时没有发生任何事情。怎么了？我是使用片段的新手。我在我的代码中添加了监听器，添加了事务。但是，当我点击一个片段时，不会替换另一个片段。 MainActivity：

  public class MainActivity extends Activity {
    MainList fragmenlist;
        FragmentTransaction ftrans;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    fragmenlist = new MainList();
            ftrans = getFragmentManager().beginTransaction();
            ftrans.add(R.id.FragmentCont,fragmenlist);
            ftrans.commit();
        }

MainListFragment：

public class MainList extends ListFragment  implements AdapterView.OnItemClickListener{
    ListView mainList;
    private static String url = "https://fierce-citadel-4259.herokuapp.com/hamsters";
    private static final String TITLE = "title";
    private static final String DESCRIPTION = "description";
    private static final String IMAGE = "image";
    ArrayList<HashMap<String,String>> jsonlist1 = new ArrayList<HashMap<String, String>>();
    public View onCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.list_fragme, null);
        mainList = (ListView)v.findViewById(android.R.id.list);
        mainList.setOnItemClickListener(this);
        return v;
    }




public void onActivityCreated(Bundle savedInstanceState){
    super.onActivityCreated(savedInstanceState);
new ProgressTask().execute();

}

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
String title = jsonlist1.get(position).get("title");
String description= jsonlist1.get(position).get("description");
String image = jsonlist1.get(position).get("image");
        MyDetailFragment detailFragment = new MyDetailFragment();
        Bundle bundle = new Bundle();
        bundle.putString("title",title);
        bundle.putString("description", description);
        bundle.putString("image", image);
        detailFragment.setArguments(bundle);
        FragmentTransaction fragmentTransaction = getActivity().getFragmentManager().beginTransaction();
        fragmentTransaction.replace(R.id.FragmentCont,detailFragment);
        fragmentTransaction.addToBackStack(null);
        fragmentTransaction.commit();
    }

    private class ProgressTask extends AsyncTask<String,Void,Boolean> {
        private ProgressDialog dialog;
        private Activity activity;
        private MainActivity context;
        private String[] params;

        public ProgressTask(MainActivity activity) {
            this.activity = getActivity();
            context = activity;
            dialog = new ProgressDialog(getActivity().getApplicationContext());

            }

        public ProgressTask() {
            dialog = new ProgressDialog(getActivity().getApplicationContext());
        }

        @Override
        protected Boolean doInBackground(String... params) {
            this.params = params;
            JSONParser jParser = new JSONParser();
            JSONArray json = jParser.getJSONFromUrl(url);
            for(int i =0;i<json.length();i++) {
                try {
                    JSONObject c = json.getJSONObject(i);
                    String vtitle = c.getString(TITLE);
                    String vdescription = c.getString(DESCRIPTION);
                    String vimage = c.getString(IMAGE);


                    HashMap<String, String> map = new HashMap<>();
                    map.put(TITLE, vtitle);
                    map.put(DESCRIPTION, vdescription);
                    map.put(IMAGE, vimage);

                    jsonlist1.add(map);

                } catch (JSONException e) {
                    e.printStackTrace();
                }
        }
            return null;
    }


        protected void onPreExecute(){

        }
        protected void onPostExecute(final Boolean success){


            try{
                if((this.dialog != null)&& this.dialog.isShowing()){
                    this.dialog.dismiss();
                }


                    CustomListAdapter adapter = new CustomListAdapter(getActivity(), jsonlist1, R.layout.list_item, new String[]{TITLE, DESCRIPTION}, new int[]{R.id.title, R.id.description});
                   mainList.setAdapter(adapter);




            }catch
                    (final IllegalArgumentException e){e.printStackTrace();}
        }

    }
}