Caldroid Null對象參考

Question

我在片段中使用Caldroid庫作爲我的應用程序。每當我嘗試添加一條語句來編輯Caldroid Frgment時，它會給我一個caldroid片段上的空對象引用。它看起來像我做了所有的文件說要做的設置。

public class CalendarFragment extends Fragment { 

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

public static CalendarFragment getInstance(int position) { 
    CalendarFragment myFragment = new CalendarFragment(); 
    Bundle args = new Bundle(); 
    args.putInt("position", position); 
    myFragment.setArguments(args); 
    return myFragment; 
} 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    CaldroidFragment caldroidFragment = new CaldroidFragment(); 
    Bundle args = new Bundle(); 
    Calendar cal = Calendar.getInstance(); 
    args.putInt(CaldroidFragment.MONTH, cal.get(Calendar.MONTH) + 1); 
    args.putInt(CaldroidFragment.YEAR, cal.get(Calendar.YEAR)); 
    args.putBoolean(CaldroidFragment.ENABLE_SWIPE, false); 
    args.putBoolean(CaldroidFragment.SHOW_NAVIGATION_ARROWS, true); 
    caldroidFragment.setArguments(args); 

    FragmentTransaction t = getActivity().getSupportFragmentManager().beginTransaction(); 
    t.replace(R.id.calendarLayout, caldroidFragment); 
    t.commit(); 

    caldroidFragment.getMonthTitleTextView().setTextColor(Color.BLACK); 
} 

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

    return rootView; 
} 

這是崩潰，行，或任何線具有caldroidFragment.blala

caldroidFragment.getMonthTitleTextView().setTextColor(Color.BLACK); 

這裏的錯誤

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setTextColor(int)' on a null object reference 
     at com.gigstudios.habittracker.CalendarFragment.onCreate(CalendarFragment.java:46) 
     at android.support.v4.app.Fragment.performCreate(Fragment.java:1766) 
     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:917) 
     at android.support.v4.app.FragmentManagerImpl.performPendingDeferredStart(FragmentManager.java:846) 
     at android.support.v4.app.Fragment.setUserVisibleHint(Fragment.java:860) 
     at android.support.v4.app.FragmentPagerAdapter.setPrimaryItem(FragmentPagerAdapter.java:130) 
     at android.support.v4.view.ViewPager.populate(ViewPager.java:1103) 
     at android.support.v4.view.ViewPager.populate(ViewPager.java:951) 
     at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1473) 
     at android.view.View.measure(View.java:17440) 
     at android.widget.LinearLayout.measureVertical(LinearLayout.java:875) 
     at android.widget.LinearLayout.onMeasure(LinearLayout.java:613) 
     at android.view.View.measure(View.java:17440) 
     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5465) 
     at android.widget.FrameLayout.onMeasure(FrameLayout.java:430) 
     at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:124) 
     at android.view.View.measure(View.java:17440) 
     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5465) 
     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436) 
     at android.widget.LinearLayout.measureVertical(LinearLayout.java:722) 
     at android.widget.LinearLayout.onMeasure(LinearLayout.java:613) 
     at android.view.View.measure(View.java:17440) 
     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5465) 
     at android.widget.FrameLayout.onMeasure(FrameLayout.java:430) 
     at android.view.View.measure(View.java:17440) 
     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5465) 
     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436) 
     at android.widget.LinearLayout.measureVertical(LinearLayout.java:722) 
     at android.widget.LinearLayout.onMeasure(LinearLayout.java:613) 
     at android.view.View.measure(View.java:17440) 
     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5465) 
     at android.widget.FrameLayout.onMeasure(FrameLayout.java:430) 
     at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2560) 
     at android.view.View.measure(View.java:17440) 
     at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2031) 
     at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1189) 
     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1402) 
     at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1077) 
     at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5884) 
     at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767) 
     at android.view.Choreographer.doCallbacks(Choreographer.java:580) 
     at android.view.Choreographer.doFrame(Choreographer.java:550) 
     at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753) 
     at android.os.Handler.handleCallback(Handler.java:739) 
     at android.os.Handler.dispatchMessage(Handler.java:95) 
     at android.os.Looper.loop(Looper.java:135) 
     at android.app.ActivityThread.main(ActivityThread.java:5312) 
     at java.lang.reflect.Method.invoke(Native Method) 
     at java.lang.reflect.Method.invoke(Method.java:372) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696) 

建議，非常感謝！

Answer 1

問題是Caldroid片段尚未初始化。你必須等到初始化Caldroid是一個片段，它有自己的生命週期。 caldroid片段有自己的事件。當片段的視圖準備就緒時，它會觸發onCaldroidViewCreated（）事件。 ：

caldroidFragment.setCaldroidListener(new CaldroidListener() { 

     @Override 
     public void onSelectDate(Date date, View view) { 
     } 

     @Override 
     public void onChangeMonth(int month, int year) { 
     } 

     @Override 
     public void onCaldroidViewCreated() { 
      super.onCaldroidViewCreated(); 
      caldroidFragment.getMonthTitleTextView().setTextColor(Color.BLACK); 

     } 
    });