FragmentPagerAdapter无法在Orientation Change上恢复片段

Question

编辑：我发现Activity正在保存实例，但Fragments保存的数据并没有使它保存到Activity savedInstanceState。我将当前时间保存在outState中，但它没有一路向上，因为活动在其SavedInstanceState中没有任何内容，如果我将它打印到logcat，则返回'null'。 ..

我正在构建一个内置了countup和countdown计时器的应用程序。计时器的基本托管活动是FragmentActivity，它托管一个FragementPagerAdapter，它会在代码中膨胀两个片段（我没有给片段提供id在XML中，因为它们未被定义为.xml中的片段。一切都很有效，直到方向改变，然后活动看起来像是失去了与旧片段的联系，只是选择创建新的片段。这意味着任何当前倒计时都会丢失，并且在配置更改时也会丢失所选择的任何时间。我需要保持计数（如果它开始）和当前显示的任何数字....

我知道Adapter应该自己处理这些事情，我在OnCreate和OnCreateView中都设置了SetRetainInstance（true）。

我在Fragment代码中放入钩子，让我知道每当saveInstanceState为非null时，至少我知道发生了什么，但似乎实例总是为NULL，并且它从头创建...总是

其他一些解决方案让我重写了instantiateItem，但似乎它仅用于重置回调，其他人更改Manifest中的设置（不赞成）....其他解决方案在我看来就像我有设置对......但很明显，我在路上弄得一团糟。我只是为FragmentActivity，FragementPagerAdapter以及一些片段代码提供代码，因为我不想使用可能不是问题的代码来垃圾邮件。

FragmentActivity

public class Timer_Main extends FragmentActivity {
    ViewPager pager;
    Timer_Pager mAdapter;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.timer_pager);

        mAdapter = new Timer_Pager(this, getSupportFragmentManager());

        pager = (ViewPager) findViewById(R.id.timer_pager_display);
        pager.setAdapter(mAdapter);

    }

    public static String getTitle(Context ctxt, int position) {
                // TODO Auto-generated method stub
        return null;
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt("pageItem", pager.getCurrentItem());

    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);

    }
}    

FragementPagerAdapter

public class Timer_Pager extends FragmentPagerAdapter{
    Context ctxt = null;
    public Timer_Pager(Context ctxt, FragmentManager fm) {
        super(fm);
        this.ctxt = ctxt;
        }


    @Override
    public Fragment getItem(int position) {

        switch (position) {
        case 0: {
            return(Countdown_Fragment.newInstance());
        }
        case 1:
            return(Countup_Fragment.newInstance());
        }
        return null;
    }

    @Override
    public String getPageTitle(int position) {

        switch (position) {
        case 0: 
            return(String.format(ctxt.getString(R.string.Countdown_label)));
        case 1: 
            return(String.format(ctxt.getString(R.string.Countup_label)));
        }
        return null;
    }

    @Override
    public int getCount() {
        // doing only three pages, right now...one for countdown, one for countup,         and one for Tabata.
        return 2;
    }

    private static String makeFragmentName(int viewId, int position)
    {
         return "android:switcher:" + viewId + ":" + position;
    }
}    

Fragment中有更多的代码，所以我将推出应该是问题的核心......如果需要更多，我会将其拼接。

public class Countdown_Fragment extends Fragment implements OnClickListener {
    Calendar CountdownTime = Calendar.getInstance();
    static AutoResizeTextView tv;
    static ImageButton HoursUp;
    static ImageButton HoursDown;
    static ImageButton MinutesUp;
    static ImageButton MinutesDown;
    static ImageButton SecondsUp;
    static ImageButton SecondsDown;
    static ImageButton Reset;
    static ImageButton StartPausecount;
    static ImageButton Stopcount;
    static Boolean Arewecounting = false;
    static Boolean Arewecountingdown = false;
    static AutoResizeTextView ThreetwooneGO;
    static MyCountdownTimer Countdown_Timer_Activity;
    ThreetwooneCount Start_countdown;
    static Long MillstoPass;

    static Countdown_Fragment newInstance() {

        Countdown_Fragment frag = new Countdown_Fragment();
        return (frag);
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {

        outState.putString("CurrentTimer", (String) tv.getText());
        Log.v("status", "saved fragment state" + tv.getText());
        super.onSaveInstanceState(outState);
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);

    }

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

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

            setRetainInstance(true);
            View result = inflater.inflate(R.layout.countdown_timer_layout,
                container, false);
        tv = (AutoResizeTextView) result.findViewById(R.id.timer_textview);
        tv.setOnClickListener(new View.OnClickListener() {
            public void onClick(View arg0) {
                new TimePickerDialog(getActivity(), t, 0, 0, true).show();
            }
        });
        if (savedInstanceState != null) {
            Log.v("status", "fragment is NOT empty");
            tv.setText(savedInstanceState.getString("CurrentTimer",
                    tv.toString()));
        } else {
            Log.v("status", "fragment is empty");
        //  tv.setText("00:00:00");

        }
        tv.resizeText();

        ThreetwooneGO = (AutoResizeTextView) result
                .findViewById(R.id.timer_countdown_text);

        HoursUp = (ImageButton) result.findViewById(R.id.hours_up);
        HoursDown = (ImageButton) result.findViewById(R.id.hours_down);
        MinutesUp = (ImageButton) result.findViewById(R.id.minutes_up);
        MinutesDown = (ImageButton) result.findViewById(R.id.minutes_down);
        SecondsUp = (ImageButton) result.findViewById(R.id.seconds_up);
        SecondsDown = (ImageButton) result.findViewById(R.id.seconds_down);
        Reset = (ImageButton) result.findViewById(R.id.reset);
        StartPausecount = (ImageButton) result
                .findViewById(R.id.startpausecount);
        Stopcount = (ImageButton) result.findViewById(R.id.stopcount);

        HoursUp.setOnClickListener(this);
        HoursDown.setOnClickListener(this);
        SecondsUp.setOnClickListener(this);
        SecondsDown.setOnClickListener(this);
        MinutesUp.setOnClickListener(this);
        MinutesDown.setOnClickListener(this);
        Reset.setOnClickListener(this);
        StartPausecount.setOnClickListener(this);
        Stopcount.setOnClickListener(this);

        return (result);
    }

    public void chooseTime(View v) {
        new TimePickerDialog(getActivity(), t, 0, 0, true).show();
    }

    TimePickerDialog.OnTimeSetListener t = new TimePickerDialog.OnTimeSetListener() {
        public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
            CountdownTime.set(Calendar.HOUR_OF_DAY, hourOfDay);
            CountdownTime.set(Calendar.MINUTE, minute);
            CountdownTime.set(Calendar.SECOND, 0);
            CountdownTime.set(Calendar.MILLISECOND, 0);

            updateLabel();
        }
    };

    private void updateLabel() {

        String entiretime;
        entiretime = String.format("%tT", CountdownTime);
        tv.setText(entiretime);
    }

这是我用于倒计时的计时器......

public class MyCountdownTimer {

private long millisInFuture;
private long countDownInterval;
Countdown_Fragment ctxt;
AutoResizeTextView Timer_edit;
private volatile boolean IsStopped = false;

public MyCountdownTimer(long pMillisInFuture, long pCountDownInterval,
        AutoResizeTextView Artv) {
    this.millisInFuture = pMillisInFuture;
    this.countDownInterval = pCountDownInterval;

    Timer_edit = Artv;

}

public void Start() {

    final Handler handler = new Handler();
    final Runnable counter = new Runnable() {

        public void run() {
            if (IsStopped == false) {
                if (millisInFuture <= 0) {
                    Countdown_Fragment.done_counting();
                } else {
                    long sec = millisInFuture / 1000;
                    Timer_edit.setText(String.format("%02d:%02d:%02d",
                            sec / 3600, (sec % 3600) / 60, (sec % 60)));
                    millisInFuture -= countDownInterval;
                    handler.postDelayed(this, countDownInterval);
                }
            }
        }
    };

    handler.postDelayed(counter, countDownInterval);
}

public void Cancel() {
    IsStopped = true;
    Timer_edit = null;
    Log.v("status", "Main Timer cancelled");
    // this.ctxt = null;

}
public long whatisourcount(){
    return(millisInFuture);
}
}

Answer 1

事实证明，RetainInstance导致自身与ViewPager / Adapter / FragmentManager之间发生冲突。删除它会导致寻呼机正确地重建碎片，包括我以前没有的TextView。我也开始在OnCreateView中收到一个Bundle，在RetainInstance设置为True之前它总是为null。

我必须删除RetainInstance并利用OnSaveInstanceState和OnCreateView在Fragment销毁之前传递Fragment的当前状态，然后在OnCreateView中重新创建它以将Fragment重置为它被销毁之前的状态。 / p>

我希望我用来倒计时的Runnable可以存活，或者我能够重新连接它，但我找不到办法。我必须以毫秒为单位保存当前计数，然后传回Fragment继续它离开的地方。这不是什么大不了的事，但我很想知道你是否真的可以重新附上所有这些东西。在配置更改后，Runnable DOES仍然继续，但它不再更新UI上的任何内容，因此当我在OnSaveInstanceState内时，我尝试取消回调并将其置空。

我也在阅读我只需要将RetainInstance用于附加了AsyncTask的项目或其他类似项目的项目....否则，只需在代码中重建它。