如何实现 onBackPressed() &片段中的意图? [英] How to implement onBackPressed() & intents in fragment?

问题描述

我知道 onBackPressed() 是活动中的一种方法，但是，我想在片段中使用该功能，以便在按下后退按钮时，它会通过 Intent 重定向到另一个活动.有什么解决办法吗?

I know that onBackPressed() is a method in activity but, I want to use the functionality in fragments such that when back button is pressed, it gets redirected to another activity via Intent. Is there any solution to this ?

public class News_Events_fragment extends Fragment {
ProgressDialog pd;
ListView lv1;
SharedPreferences sharedPreferences = null;
int NotiCount;
TextView txt_title, txt_msg, textView;
Context context;
Intent intent ;
ArrayList<SliderMsgTitleModel> CurrentOfficersPastList;
NewsActivityAdapter pastAdapter;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    context = (Context) getActivity();

    View rootView = inflater.inflate(R.layout.activity_news, container, false);

    new AsyncTask<Void, Void, ArrayList<SliderMsgTitleModel>>() {

        protected void onPreExecute() {
            pd = new ProgressDialog(getActivity());
            pd.setCancelable(true);
            pd.setTitle("UPOA");
            pd.setMessage("Please wait,loading the data...");
            pd.show();
        }

        @Override
        protected ArrayList<SliderMsgTitleModel> doInBackground(
                Void... params) {
            System.out.println("In Background");
            CurrentOfficersPastList = new ArrayList<SliderMsgTitleModel>();
            // display view for selected nav drawer item
            ParseQuery<ParseObject> query = ParseQuery.getQuery("message");
            query.whereEqualTo("featured_status", true);
            // query.whereEqualTo("push_status", true);

            query.orderByDescending("updatedAt");

            query.selectKeys(Arrays.asList("title"));
            query.selectKeys(Arrays.asList("message"));
            try {
                query.setCachePolicy(ParseQuery.CachePolicy.NETWORK_ELSE_CACHE);
                List<ParseObject> results = query.find();
                for (int i = 0; i < results.size(); i++) {
                    ParseObject object = results.get(i);
                    CurrentOfficersPastList.add(new SliderMsgTitleModel(
                            object.getString("title"), object
                                    .getString("message")));
                    System.out.println("title is=="
                            + object.getString("title") + "&& message is"
                            + object.getString("message") + "size is"
                            + CurrentOfficersPastList.size());

                }
            } catch (Exception e) {
                e.getMessage();
            }
            pd.dismiss();

            return CurrentOfficersPastList;
        }

        @SuppressWarnings("unchecked")
        @Override
        protected void onPostExecute(ArrayList<SliderMsgTitleModel> value) {

            pd.dismiss();
            /*Intent ent = new Intent(getActivity(), NewsActivity.class);
            ent.putExtra("NEWSLIST", (ArrayList<SliderMsgTitleModel>) value);
            startActivity(ent);
            System.out.println("Value is" + value.size());*/

            CurrentOfficersPastList = new ArrayList<SliderMsgTitleModel>();
            CurrentOfficersPastList = value;
            lv1 = (ListView) getActivity().findViewById(R.id.list_title);
            pastAdapter = new NewsActivityAdapter(getActivity(), R.layout.activity_news_txt, CurrentOfficersPastList);
            lv1.setAdapter(pastAdapter);

        }
    }.execute();

    return rootView;
}

public void onBackPressed() {
    // TODO Auto-generated method stub
    //super.onBackPressed();
    //Toast.makeText(getApplicationContext(), "click",2000).show();
            String cameback="CameBack";
            intent = new Intent(getActivity(),HomeActivity.class);
            intent.putExtra("Comingback", cameback);
            startActivity(intent);
}

 }

推荐答案

覆盖 onKeyDown 而不是 onBackPressed.不必要 .但这对我有用

Override onKeyDown instead of onBackPressed. Not necessarily . But this works for me

public boolean onKeyDown(int keyCode, KeyEvent event) {

        switch (keyCode) {
            case KeyEvent.KEYCODE_BACK:
                String cameback="CameBack";
                intent = new Intent(getActivity(),HomeActivity.class);
                intent.putExtra("Comingback", cameback);
                startActivity(intent);
                return true
    }
            return false;
}

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