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mahdi10539 · ۱۳۹۴/۱۲/۱۳, ۰۲:۵۵ ب.ظ

سلام

دوستان کسی تا حالا با ViewPager بدون TabHost در Nested Fragment کار کرده

کد پی‌اچ‌پی:
Logcat : 

03-03 05:17:37.300 1415-1415/com.olomrayan.obituary D/AndroidRuntime: Shutting down VM
03-03 05:17:37.305 1415-1415/com.olomrayan.obituary E/AndroidRuntime: FATAL EXCEPTION: main
                                                                      Process: com.olomrayan.obituary, PID: 1415
                                                                      java.lang.NullPointerException: Attempt to invoke virtual method 'int java.util.ArrayList.size()' on a null object reference
                                                                          at android.support.v4.app.FragmentManagerImpl.getFragment(FragmentManager.java:667)
                                                                          at android.support.v4.app.FragmentStatePagerAdapter.restoreState(FragmentStatePagerAdapter.java:211)
                                                                          at android.support.v4.view.ViewPager.onRestoreInstanceState(ViewPager.java:1319)
                                                                          at android.view.View.dispatchRestoreInstanceState(View.java:14746)
                                                                          at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:3121)
                                                                          at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:3127)
                                                                          at android.view.View.restoreHierarchyState(View.java:14724)
                                                                          at android.support.v4.app.Fragment.restoreViewState(Fragment.java:468)
                                                                          at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1094)
                                                                          at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1248)
                                                                          at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
                                                                          at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1613)
                                                                          at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:517)
                                                                          at android.os.Handler.handleCallback(Handler.java:739)
                                                                          at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                          at android.os.Looper.loop(Looper.java:148)
                                                                          at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                                          at java.lang.reflect.Method.invoke(Native Method)
                                                                          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                                          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

MainActivity:

کد پی‌اچ‌پی:
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.Toast;

import java.io.IOException;
import java.io.InputStream;

public class MainActivity extends AppCompatActivity implements OnFragmentInteractionListener {

    NewFragment newFragment = null;
    MainFragment mainFragment = null;
    String CurrentFragment = "MainActivity";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        initFirstLoad();

        Bitmap bitmap = null;
        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        try {
            InputStream is = getAssets().open("images/new.png");
            bitmap = BitmapFactory.decodeStream(is);
        } catch (IOException e) {
            e.printStackTrace();
        }

        fab.setImageBitmap(bitmap);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                if (newFragment == null) {
                    newFragment = NewFragment.newInstance();
                }

                if (newFragment.isVisible()) {
                    return;
                }

                CurrentFragment = "NewFragment";
                FragmentManager fragmentManager = getSupportFragmentManager();
                FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
                fragmentTransaction.add(R.id.mainfragment, newFragment, "NewFragment").addToBackStack("NewFragment");
                fragmentTransaction.commit();
            }
        });
    }

    @Override
    public void onBackPressed() {

            if (CurrentFragment.equals("NewFragment") && newFragment.isVisible()) {
                getSupportFragmentManager().popBackStack();
                CurrentFragment = getSupportFragmentManager().getFragments().get(0).getTag();
                if (CurrentFragment == null)
                    CurrentFragment = "MainActivity";

                //noinspection ConstantConditions
                getSupportActionBar().setTitle(R.string.app_name);
            }
        //super.onBackPressed();
    }

//    @Override
//    public void onBackPressed() {
//        Log.d("MYLOG",String.valueOf(getFragmentManager().getBackStackEntryCount()));
//        if (getFragmentManager().getBackStackEntryCount() > 0) {
//            getFragmentManager().popBackStack();
//        } else {
//            super.onBackPressed();
//        }
//    }

    private void initFirstLoad() {
        if (mainFragment == null) {
            mainFragment = MainFragment.newInstance();
        }
        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.add(R.id.mainfragment, mainFragment, "MainFragment").addToBackStack("MainFragment");
        fragmentTransaction.commit();

    }


    @Override
    public void onFragmentInteraction(String fragmentName, String[] Values) {

        switch (fragmentName) {
            case "AboutFragment":
                Toast.makeText(MainActivity.this, "MainActivity onFragmentInteraction From About Fragment : Uri " + Values[0], Toast.LENGTH_SHORT).show();
                break;
        }
    }
} 

MainFragment:

کد پی‌اچ‌پی:
import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.TypedValue;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.Toast;

import com.olomrayan.obituary.Adapters.CustomAdapterRecyclerView;
import com.olomrayan.obituary.Database.DBAccess;
import com.olomrayan.obituary.Database.DBHelper;
import com.olomrayan.obituary.Models.ObituaryItem;

import java.util.ArrayList;
import java.util.List;

import jp.wasabeef.recyclerview.adapters.AlphaInAnimationAdapter;
import jp.wasabeef.recyclerview.adapters.ScaleInAnimationAdapter;
import jp.wasabeef.recyclerview.animators.SlideInLeftAnimator;


public class MainFragment extends Fragment implements OnFragmentInteractionListener {

    private OnFragmentInteractionListener mListener;
    ProgressDialog mProgressDialog;
    View mRootView;
    List<ObituaryItem> mObituaryItemList;
    DBAccess mDBAccess;

    public MainFragment() {

    }


    public static MainFragment newInstance() {

        return new MainFragment();
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        mRootView = inflater.inflate(R.layout.fragment_main, container, false);
        return mRootView;
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);



        mObituaryItemList = new ArrayList<>();

        LoadingData loadingData = new LoadingData();
        loadingData.execute();

        RecyclerView recyclerView = (RecyclerView) mRootView.findViewById(R.id.recyclerview);
        recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
        CustomAdapterRecyclerView customAdapterRecyclerView = new CustomAdapterRecyclerView(mObituaryItemList);

        AlphaInAnimationAdapter alphaInAnimationAdapter = new AlphaInAnimationAdapter(customAdapterRecyclerView);
        recyclerView.setItemAnimator(new SlideInLeftAnimator());
        recyclerView.getItemAnimator().setChangeDuration(1000);
        alphaInAnimationAdapter.setDuration(1000);
        alphaInAnimationAdapter.setFirstOnly(false);
        alphaInAnimationAdapter.setHasStableIds(true);
        recyclerView.setAdapter(new ScaleInAnimationAdapter(alphaInAnimationAdapter));
    }

    public void onButtonPressed(String fragmentName, String[] Values ) {
        if (mListener != null) {
            mListener.onFragmentInteraction(fragmentName, Values);
        }
    }


    @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;
    }

    @Override
    public void onFragmentInteraction(String fragmentName, String[] Values) {
        switch (fragmentName) {
            case "AboutFragment":
                Toast.makeText(getActivity(), "MainFragment onFragmentInteraction From About Fragment : Uri " + Values[0], Toast.LENGTH_SHORT).show();
                break;
            default:
        }
    }

    class LoadingData extends AsyncTask<String,String,List<ObituaryItem>> {


        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            mDBAccess = DBAccess.getInstance(getActivity());

            mProgressDialog = new ProgressDialog(getActivity());
            mProgressDialog.setIndeterminate(true);
            mProgressDialog.setCancelable(false);
            mProgressDialog.setProgressStyle(android.R.attr.progressBarStyleSmall);
            mProgressDialog.show();
            WindowManager.LayoutParams params = mProgressDialog.getWindow().getAttributes();
            params.x = -20;
            params.height = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 150f, getResources().getDisplayMetrics());
            params.width = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 180f, getResources().getDisplayMetrics());
            params.y = -10;
            mProgressDialog.getWindow().setAttributes(params);
            mProgressDialog.setContentView(R.layout.loadgin_data_progressbar);
        }
        @Override
        protected List<ObituaryItem> doInBackground(String... params) {

            return mDBAccess.getSelectData(DBHelper.DB_TABLE_NAME, DBHelper.TABLE_COLUMNS_NAMES,null,null,null,null,DBHelper.TABLE_COLUMNS_CREATEDATE + " DESC");
        };



        @Override
        protected void onProgressUpdate(String... values) {
            super.onProgressUpdate(values);
        }

        @Override
        protected void onPostExecute(List<ObituaryItem> obituaryItemList) {

            mProgressDialog.dismiss();
        }
    }
} 

NewFragment:

کد پی‌اچ‌پی:
import android.content.Context;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;

import android.support.v4.view.ViewPager;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

import com.olomrayan.obituary.Adapters.CustomPagerAdapter;


public class NewFragment extends Fragment implements View.OnKeyListener {


    int CurrnetPagerItem = 1;

    private OnFragmentInteractionListener mListener;

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


    public static NewFragment newInstance() {
        new NewFragment();

        return new NewFragment();
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }


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

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

        //noinspection ConstantConditions
        final ViewPager viewPager = (ViewPager) rootView.findViewById(R.id.viewPager);

        FragmentManager fragmentManager = getChildFragmentManager();
        CustomPagerAdapter customPagerAdapter = new CustomPagerAdapter(fragmentManager);
        //customPagerAdapter.setPrimaryItem(viewPager,0,StepOneFragment.newInstance());
        Log.d("MYLOG", String.valueOf(customPagerAdapter.getCount()));
        viewPager.setAdapter(customPagerAdapter);

        viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                Log.d("MYLOG", String.valueOf(position));
                CurrnetPagerItem = position;
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });


        Button btnNext = (Button) rootView.findViewById(R.id.btnNext);

        btnNext.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {


                if (CurrnetPagerItem > 1)
                    CurrnetPagerItem = 0;

                viewPager.setCurrentItem(CurrnetPagerItem);

                CurrnetPagerItem++;

            }
        });

        ActionBar toolbar = ((AppCompatActivity) getActivity()).getSupportActionBar();

        if (toolbar != null) {
            toolbar.setHomeButtonEnabled(true);
            toolbar.setDisplayShowTitleEnabled(true);
            toolbar.setDisplayShowHomeEnabled(true);
            toolbar.setTitle("New Obituary");
        }

        return rootView;
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);


    }

    public void onButtonPressed(String[] Values) {
        if (mListener != null) {
            mListener.onFragmentInteraction("NewFragment", Values);
        }
    }


    @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;

    }


    @Override
    public boolean onKey(View v, int keyCode, KeyEvent event) {
//        if (event.getAction() == KeyEvent.ACTION_DOWN) {
//            if (keyCode == KeyEvent.KEYCODE_BACK) {
//                return true;
//            }
//        }
        return false;
    }

} 

CustomPagerAdapter:

کد پی‌اچ‌پی:
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.util.Log;

import com.olomrayan.obituary.StepOneFragment;
import com.olomrayan.obituary.StepTwoFragment;

public class CustomPagerAdapter extends FragmentPagerAdapter {



    int count = 2;
    public CustomPagerAdapter(FragmentManager fm) {
        super(fm);
        Log.d("MYLOG", "Custom Created");

    }

    @Override
    public int getCount() {
        return (count);
    }

    @Override
    public Fragment getItem(int position) {
        Fragment fragment;
        Log.d("MYLOG", String.valueOf(position));

        switch (position) {

            case 0:
                fragment = StepOneFragment.newInstance();
            break;
            case 1:
                fragment =  StepTwoFragment.newInstance();
                break;

            default:
                fragment =  null;
        }

        return fragment;
    }

} 

OnFragmentInteraction Interface :

کد پی‌اچ‌پی:
public interface OnFragmentInteractionListener {
    void onFragmentInteraction(String fragmentName,String[] Values);
} 

mainavtivity.xml

کد پی‌اچ‌پی:
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context="com.olomrayan.obituary.MainActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay" />

    </android.support.design.widget.AppBarLayout>

    <fragment
        android:layout_marginTop="64dp"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/mainfragment"
        class ="com.olomrayan.obituary.MainFragment"
        tools:layout="@layout/fragment_main" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        app:rippleColor="@color/colorAccent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        app:backgroundTint="@color/textColorPrimary"
        android:scrollbars="vertical"
        android:layout_margin="@dimen/fab_margin"
        android:src="@drawable/newo"
        app:theme="@style/MyFloatingButton"/>
</android.support.design.widget.CoordinatorLayout> 

mainfragment.xml

کد پی‌اچ‌پی:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.olomrayan.obituary.MainFragment">

<android.support.v7.widget.RecyclerView
    android:layout_width="match_parent"
    android:fitsSystemWindows="true"
    android:layout_below="@android:id/empty"
    android:layout_alignWithParentIfMissing="true"
    android:layout_height="match_parent"
    android:id="@+id/recyclerview">

</android.support.v7.widget.RecyclerView>

</RelativeLayout> 

newfragment.xml

کد پی‌اچ‌پی:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:weightSum="100"
    android:background="@color/navigationBarColor"
    tools:context="com.olomrayan.obituary.NewFragment"
    android:orientation="vertical">


    <android.support.v4.view.ViewPager
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="100">
    </android.support.v4.view.ViewPager>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/btnNext"
        android:text="Next Page" />

</LinearLayout> 

mahdi10539 · ۱۳۹۴/۱۲/۱۳, ۰۳:۲۶ ب.ظ

مشکل برطرف شد.

اشکال در مدیریت چرخه حیات NewFragment بود
بار اول که NewFragment ساخته میشه ViewPager میاد و customPagerAdapter رو راه اندازی میکنه.
CustomPagerAdapter هم میاد StepOneFragment و stepTwoFragment رو راه اندازی میکنه
چون در پیاده سازی CustomPagerAdapter از FragmentStatePagerAdapter استفاده شده قسمتی از Content و تعدا اونها در چرخه حیات ViewPager و NewFragment ذخیره میشه.

چون ما در طراحی انجام شده هنوز قسمت OnDetach مربوط به NewFragment و بقیه Fragmentها رو پیاده سازی نکردیم برای هیمن از چرخه حیات خارج نمیشن و هنگامی که دوباره NewFragment راه اندازی میشه اطلاعات قبلی مربوط به NewFragment بازگردانی میشه ولی این بار چون هنوز StepOneFragment و StepTwoFragment راه اندازی نشدن . ViewPager با اطلاعات غلط یا اشتباه پر میشه و هنوز فکر میکنه که دو Fragment گفته شده راه اندازی شدن . در حالی که راه اندازی نشدن و هیچ اطلاعاتی ازشون موجوذد نیست.
برای همین منظور پیغام خطای زیر رو میده

کد پی‌اچ‌پی:
NullPointerException: Attempt to invoke virtual method 'int java.util.ArrayList.size()' on a null object reference
                                                                          at android.support.v4.app.FragmentManagerImpl.getFragment(FragmentManager.java:667)
                                                                          at android.support.v4.app.FragmentStatePagerAdapter.restoreState(FragmentStatePagerAdapter.java:211)
                                                                          at android.support.v4.view.ViewPager.onRestoreInstanceState(ViewPager.java:1319)
                                                                          at android.view.View.dispatchRestoreInstanceState(View.java:14746) 

نکته : در استفاده از Fragment ها و NestedFragmentها همیشه با Onattach و OnDetach دقت کنید

mahdi10539 · ۱۳۹۴/۱۲/۱۳, ۰۵:۲۱ ب.ظ

فراموش کردم بگم
این هم کد مربوط به برطرف کردن مشکل

در MainActivity در رویداد onclicklistener مربوط به floatingactionbutton یا fab کد زیر رو جایگزین کنید

کد پی‌اچ‌پی:
کد قدیمی 

if (newFragment == null) {
                    newFragment = NewFragment.newInstance();
                }

                if (newFragment.isVisible()) {
                    return;
                }

                CurrentFragment = "NewFragment";
                FragmentManager fragmentManager = getSupportFragmentManager();
                FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
                fragmentTransaction.add(R.id.mainfragment, newFragment, "NewFragment").addToBackStack("NewFragment");
                fragmentTransaction.commit();
            } 

کد پی‌اچ‌پی:
کد جدید

FragmentManager fragmentManager = getSupportFragmentManager();
                FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
                newFragment = (NewFragment) fragmentManager.findFragmentByTag("NewFragment");

                if (newFragment == null) {
                    Log.d("MYLOG","NewFragment Is Nulled");
                    newFragment = NewFragment.newInstance();
                }

                if (newFragment.isVisible()) {
                    return;
                }

                Log.d("MYLOG","CurrentFragment Is "+CurrentFragment);
                CurrentFragment = "NewFragment";
                Log.d("MYLOG","CurrentFragment Is Changed To NewFragment");

                fragmentTransaction.add(R.id.mainfragment, newFragment, "NewFragment").addToBackStack("NewFragment");
                fragmentTransaction.commit(); 

نکته : بنا بر طراحی خاص برنامه . الگوی singleton بر روی کلاس NewFragment پیاده سازی ( شبیه سازی ) شده. هرچند Fragment ها به این خاطر طراحی شدن تا بشه از اونها چندین بار استفاده کرد.

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