[英]Interface communication between two Fragments
I have implemented a master-detail view. 我已经实现了主从视图。 With two fragments being displayed side by side on a large 10-inch screen.
在10英寸大屏幕上并排显示两个片段。 Fragment A Displays a list of orders.
片段A显示订单列表。 When an order is selected the details of that order are displayed in Fragment B .
选择订单后,该订单的详细信息将显示在片段B中 。 In fragments B after processing the order items.
在片段B中处理了订单项之后。 I want to notify Fragment A to update the UI and colour the processed order in the list of orders.
我想通知片段A更新UI,并在订单列表中为已处理的订单上色。
The current method that I have tried was creating an interface in Fragment B implementing the interface in Fragment A . 我已经尝试过的当前方法是创造在片段B实现在片段A的接口的接口。 However, this method does not seem to work as when I try and set the instance of the interface in the onAttach method the application crashes as the context is still the context of Fragment A .
但是,此方法似乎不起作用,因为当我尝试在onAttach方法中设置接口的实例时,应用程序崩溃了,因为上下文仍然是Fragment A的上下文。
@Override
public void onAttach(@NonNull Context context)
{
super.onAttach(context);
if (context instanceof OnStockAddedListener)
{
onStockAddedListener = (OnStockAddedListener) this.getActivity();
} else
{
throw new ClassCastException(context.toString());
}
}
How can i go about doing this. 我该怎么做。
Your fragments are hosted in an Activity
, and that activity is what's passed to onAttach()
. 您的片段托管在一个
Activity
,该活动就是传递给onAttach()
。 So your activity needs to be responsible for dispatching communication between your fragments. 因此,您的活动需要负责在片段之间调度通信。
So, in FragmentB, you cast your Activity to your listener interface when you're attached: 因此,在FragmentB中,连接后将Activity投射到侦听器接口:
@Override
public void onAttach(Context context) {
super.onAttach(context);
this.onStockAddedListener = (OnStockAddedListener) context;
}
And you implement the interface in your Activity: 然后在Activity中实现接口:
public class MyActivity implements OnStockAddedListener {
@Override
public void onStockAdded(Stock stock) {
FragmentA fragmentA = (FragmentA) getSupportFragmentManager()
.findFragmentByTag(/* insert tag here */);
fragmentA.handleStockAdded(stock);
}
}
And you receive these messages in FragmentA: 并且您在FragmentA中收到以下消息:
public class FragmentA {
public void handleStockAdded(Stock stock) {
// update ui, or whatever else you need
}
}
The main thing is to not think about FragmentA talking to FragmentB, or FragmentB talking to FragmentA. 最主要的是不要考虑FragmentA与FragmentB对话,或FragmentB与FragmentA对话。 Instead, FragmentA and FragmentB both talk to the Activity, and the Activity can talk (as required) with either FragmentA or FragmentB.
相反,FragmentA和FragmentB都与Activity对话,并且Activity可以(根据需要)与FragmentA或FragmentB对话。 Everything flows through the activity.
一切都流经活动。
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