英文:
Android Listener working in activity but not in fragment
问题
我有一个活动和两个片段。我正试图从一个ArrayList中获取一个被点击的项目。在我的FragmentA中，我有一个接口：
public interface GroupListener {
public String onGroupSelected(String groupName);
}
以及
@Override
public void onAttach(@NonNull Context context) {
super.onAttach(context);
try {
groupListener = (GroupListener) context;
} catch (ClassCastException e) {
throw new ClassCastException(context.toString() + " 必须实现接口 " +
"GroupListener！");
}
}
这从列表中的一个被点击的项目获取位置：
@Override
public void onListItemClick(@NonNull ListView l, @NonNull View v, int position, long id) {
groupListener.onGroupSelected((String) getListAdapter().getItem(position));
}
然后，我在我的活动和FragmentB中都有监听器，它们看起来是相同的：
@Override
public String onGroupSelected(String groupName) {
System.out.println("在活动中的 onGroup 方法内");
return groupName;
}
@Override
public String onGroupSelected(String groupName) {
System.out.println("在FragmentB中的 onGroup 方法内");
return groupName;
}
但是，当我点击一个项目时，只有我的活动中的监听器被触发，而我的片段中的监听器没有被触发。我漏掉了什么？
英文:
I have an activity and two fragments. Im trying to get a clicked item from an arraylist. In my fragmentA I have a interface:
public interface GroupListener {
public String onGroupSelected(String groupName);
}
and
@Override
public void onAttach(@NonNull Context context) {
super.onAttach(context);
try {
groupListener = (GroupListener) context;
} catch (ClassCastException e)
{
throw new ClassCastException(context.toString() + " must implement the interface" +
"called GroupListener!");
}
}
This gets the postion from an item clicked in a list :
public void onListItemClick(@NonNull ListView l, @NonNull View v, int position, long id) {
groupListener.onGroupSelected((String) getListAdapter().getItem(position));
}
I then have the listner in my activity and in fragmentB which looks the same:
@Override
public String onGroupSelected(String groupName) {
System.out.println("in onGroup in Activity");
return groupName;
}
@Override
public String onGroupSelected(String groupName) {
System.out.println("in onGroup in fragmentB");
return groupName;
}
But when i click an item only the listener in my activity is activated, not the one in my fragment. What is it that im missing?
答案1
得分: 0
在 FragmentB 中的这部分不会触发，因为你只是从 Fragment A 与活动进行通信。
在你的活动中，可以像这样做：
@Override
public String onGroupSelected(String groupName) {
System.out.println("在活动中的 onGroupSelected 方法内");
FragmentB frag = //使用片段管理器找到你的片段
frag.onGroupSelected(groupName);
return groupName;
}
这就是如何从活动中调用片段内的方法。
英文:
The one in FragmentB will not fire, since you are only communicating with the activity from fragment A.
In your activity do something like this:
Override
public String onGroupSelected(String groupName) {
System.out.println("in onGroup in Activity");
FragmentB frag = //find your fragment using fragment manager
frag.onGroupSelected(groupName);
return groupName;
}
This is how you call methods inside fragment from an activity
答案2
得分: 0
这个问题有点晚回答，但我找到了适合我的方法。
由于侦听器将首先通过活动获取，您可以在主活动中定义目标片段，然后调用目标片段中的方法并执行您想要的操作：
在主活动的侦听器中：
DestinationFragment fragment = (DestinationFragment) getSupportFragmentManager().findFragmentById(R.id.destination_fragment);
fragment.sampleListener(bundle);
在目标片段中定义sampleListener并编写您的代码。
英文:
It is a little late to answer but I found a way that works for me.
As listener will first get by activity, you can define destination fragment in the Main activity and then call a method in the destination fragment and do what you want:
In the main Activity listener
DestinationFragment fragment = (DestinationFragment) getSupportFragmentManager().findFragmentById(R.id.destination_fragment);
fragment.sampleListener(bundle);
In the destination fragment define sampleListener and write your code.
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