Bundle是否傳遞onCreate到Activity和Child Fragment不同？

Question

是否將Bundle的私人副本傳遞給Fragment和父母Activity？

我嘗試在onSaveInstanceState的Fragment中保存鍵值對，並嘗試在Activity的onCreate中檢索它。它缺席那裏。

但是這兩者之間似乎也有聯繫。 當我通過null到super.onCreate的ActivityBundle傳遞給Fragment的onCreate也是null。

Answer 1

Bundle要發送到onCreate對於Activity和Fragment是完全不同的。如果您將null發送到super.onCreate - >活動將從頭開始重新創建所有fragments。所以你的Fragment將收到null - >也。因爲這是新fragment

---

這是的FragmentActivity代碼的一部分：

/** 
* Perform initialization of all fragments and loaders. 
*/ 
@SuppressWarnings("deprecation") 
@Override 
protected void onCreate(@Nullable Bundle savedInstanceState) { 
    mFragments.attachHost(null /*parent*/); 

    super.onCreate(savedInstanceState); 

    NonConfigurationInstances nc = 
      (NonConfigurationInstances) getLastNonConfigurationInstance(); 
    if (nc != null) { 
     mFragments.restoreLoaderNonConfig(nc.loaders); 
    } 
    if (savedInstanceState != null) { 
     Parcelable p = savedInstanceState.getParcelable(FRAGMENTS_TAG); 
     mFragments.restoreAllState(p, nc != null ? nc.fragments : null); 

     // Check if there are any pending onActivityResult calls to descendent Fragments. 
     if (savedInstanceState.containsKey(NEXT_CANDIDATE_REQUEST_INDEX_TAG)) { 
      mNextCandidateRequestIndex = 
        savedInstanceState.getInt(NEXT_CANDIDATE_REQUEST_INDEX_TAG); 
      int[] requestCodes = savedInstanceState.getIntArray(ALLOCATED_REQUEST_INDICIES_TAG); 
      String[] fragmentWhos = savedInstanceState.getStringArray(REQUEST_FRAGMENT_WHO_TAG); 
      if (requestCodes == null || fragmentWhos == null || 
         requestCodes.length != fragmentWhos.length) { 
       Log.w(TAG, "Invalid requestCode mapping in savedInstanceState."); 
      } else { 
       mPendingFragmentActivityResults = new SparseArrayCompat<>(requestCodes.length); 
       for (int i = 0; i < requestCodes.length; i++) { 
        mPendingFragmentActivityResults.put(requestCodes[i], fragmentWhos[i]); 
       } 
      } 
     } 
    } 

    if (mPendingFragmentActivityResults == null) { 
     mPendingFragmentActivityResults = new SparseArrayCompat<>(); 
     mNextCandidateRequestIndex = 0; 
    } 

    mFragments.dispatchCreate(); 
}