android - 在 onCreate 上传递给 Activity 和 Child Fragment 的 Bundle 是否不同？

Question

是否将私有副本Bundle传递给Fragment父级Activity？

我尝试在 Activity 中保存键、值对onSaveInstanceState并Fragment尝试在onCreateActivity 中检索它。它在那里不存在。

但两者之间似乎也有联系。当我null传给super.onCreate的传给Activity的也是。BundleFragmentonCreatenull

Answer 1

Bundle它被发送到onCreate并且Activity完全Fragment不同。如果您要发送null到super.onCreate-> 活动，将fragments从头开始重新创建所有内容。所以你Fragment也会收到null->。因为这是新的fragment

---

这是代码的一部分FragmentActivity：

/**
 * 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();
}