Android Fragment.java中的getActivity（）方法解析

廢話不多說，看源碼：

/**
     * Return the {@link FragmentActivity} this fragment is currently associated with.
     * May return {@code null} if the fragment is associated with a {@link Context}
     * instead.
     *
     * @see #requireActivity()
     */
    @Nullable
    final public FragmentActivity getActivity() {
        return mHost == null ? null : (FragmentActivity) mHost.getActivity();
    }

大概意思爲：返回一個和此fragment綁定的FragmentActivity或者其子類的實例。相反，如果此fragment綁定的是一個context的話，可能會返回null。