从活动创建片段时，getView 返回 null [英] getView returning null when fragment has been created from an activity

问题描述

我有一个可以工作的平板电脑应用程序，我现在也想在手机上使用它.在一张桌子上，屏幕上有两个片段，一个是列表片段，一个是详细信息片段.当在手机上时，列表片段会出现并在按下列表项时创建一个新活动.此活动仅在 onCreate() 方法中创建片段并将其提交到屏幕，如下所示.

I have a working tablet application which I am now trying to make work on phones too. On a table there is two fragments on the screen a list fragment and a details fragment. When on a phone the list fragment appears and creates a new activity when a list item is pressed. This activity simply creates the fragment in the onCreate() method and commits it to the screen as follows.

// Place an DeallDetailsFragment as our content pane
DealDetailsFragment f = new DealDetailsFragment();
getFragmentManager().beginTransaction().add(android.R.id.content, f).commit();
getFragmentManager().executePendingTransactions();

这是按预期工作的，但是在此活动中，我需要告诉片段要加载和显示哪些详细信息.在我的 DealDetailsFragment 类中，我有一个 updateDeal() 方法，它更新内容如下.

This is working as expected however from within this activity I need to tell the fragment what details to load and display. In my DealDetailsFragment class I have a updateDeal() method which updates the content as follows.

if (deal==null) { // could be null if user presses the loading deals list item before it loads
    return;
}
this.deal=deal;
if (dealTitle==null) { // get the view objects only once
    holder = new ViewHolder();  
    holder.dealHeat=(TextView) getView().findViewById(R.id.dealDetails_heat_textView);
    holder.dealPrice=(TextView) getView().findViewById(R.id.dealDetails_price_textView);
    holder.dealRetailer=(TextView) getView().findViewById(R.id.dealDetails_retailer_textView);
    holder.dealTitle=(TextView) getView().findViewById(R.id.dealDetails_title_textView);
    holder.dealDesc=(TextView) getView().findViewById(R.id.dealDetails_desc_textView);
    holder.goToButton= (LinearLayout) getView().findViewById(R.id.dealDetails_goToDeal);
    holder.dealImage=(ImageView) getView().findViewById(R.id.dealDetails_imageView);
    holder.postedBy=(TextView) getView().findViewById(R.id.dealDetails_poster_textView);
    holder.datePosted=(TextView) getView().findViewById(R.id.dealDetails_date_textView);

getView() 在仅显示单个片段的手机上运行应用程序时返回 null.

getView() is returning null when the application is ran on a phone where there is only a single fragment shown.

有什么想法吗?不幸的是，在线提供的片段示例并不多.

Any ideas? Unfortunately, there is not many fragment examples available online.

推荐答案

移动你的方法调用以在 onCreateView 期间执行，并使用你正在膨胀的视图而不是 getView().有关更多信息，请参阅片段生命周期:https://developer.android.com/guide/components/fragments.html#Creating

Move your method call to be executed during onCreateView, and use the view you are inflating for reference instead of getView(). See the fragment lifecycle for more information: https://developer.android.com/guide/components/fragments.html#Creating

和 getView() 的文档解释了为什么它在 onCreateView(LayoutInflater, ViewGroup, Bundle) 返回之前返回 null:

and the documentation of getView() that explains why it returns null before onCreateView(LayoutInflater, ViewGroup, Bundle) returns:

getView()获取片段布局的根视图(由 onCreateView(LayoutInflater, ViewGroup, Bundle) 返回的视图)(如果提供).

getView() Get the root view for the fragment's layout (the one returned by onCreateView(LayoutInflater, ViewGroup, Bundle)), if provided.

https://developer.android.com/reference/android/app/Fragment.html#getView()

这篇关于从活动创建片段时，getView 返回 null的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！