我使用DialogFragments的一些事情:从列表中选择项目,输入文本。
将值(即字符串或列表中的项)返回给调用活动/片段的最佳方法是什么?
目前,我正在使调用活动实现驳回监听器,并给予DialogFragment对活动的引用。然后Dialog在activity中调用ondismiss方法,activity从DialogFragment对象中抓取结果。非常混乱,它不能在配置更改(方向更改),因为DialogFragment失去了对活动的引用。
谢谢你的帮助。
我使用DialogFragments的一些事情:从列表中选择项目,输入文本。
将值(即字符串或列表中的项)返回给调用活动/片段的最佳方法是什么?
目前,我正在使调用活动实现驳回监听器,并给予DialogFragment对活动的引用。然后Dialog在activity中调用ondismiss方法,activity从DialogFragment对象中抓取结果。非常混乱,它不能在配置更改(方向更改),因为DialogFragment失去了对活动的引用。
谢谢你的帮助。
当前回答
好吧,现在回答可能为时已晚,但这是我从DialogFragment中获得结果的方法。非常类似于@brandon的回答。 这里我从一个片段调用DialogFragment,只是把这段代码放在你调用你的对话框的地方。
FragmentManager fragmentManager = getFragmentManager();
categoryDialog.setTargetFragment(this,1);
categoryDialog.show(fragmentManager, "dialog");
where categoryDialog是我的DialogFragment,我想调用这之后,在你的DialogFragment的实现中放置这段代码,你在意图中设置你的数据。resultCode的值为1,可以设置或使用system Defined。
Intent intent = new Intent();
intent.putExtra("listdata", stringData);
getTargetFragment().onActivityResult(getTargetRequestCode(), resultCode, intent);
getDialog().dismiss();
现在回到调用片段并实现该方法。在if条件中使用resultCode和requestCode检查数据有效性或结果成功。
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
//do what ever you want here, and get the result from intent like below
String myData = data.getStringExtra("listdata");
Toast.makeText(getActivity(),data.getStringExtra("listdata"),Toast.LENGTH_SHORT).show();
}
其他回答
或者像下面这样共享ViewModel:
public class SharedViewModel extends ViewModel {
private final MutableLiveData<Item> selected = new MutableLiveData<Item>();
public void select(Item item) {
selected.setValue(item);
}
public LiveData<Item> getSelected() {
return selected;
}
}
public class MasterFragment extends Fragment {
private SharedViewModel model;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
model = ViewModelProviders.of(getActivity()).get(SharedViewModel.class);
itemSelector.setOnClickListener(item -> {
model.select(item);
});
}
}
public class DetailFragment extends Fragment {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
SharedViewModel model = ViewModelProviders.of(getActivity()).get(SharedViewModel.class);
model.getSelected().observe(this, { item ->
// Update the UI.
});
}
}
https://developer.android.com/topic/libraries/architecture/viewmodel#sharing_data_between_fragments
好吧,现在回答可能为时已晚,但这是我从DialogFragment中获得结果的方法。非常类似于@brandon的回答。 这里我从一个片段调用DialogFragment,只是把这段代码放在你调用你的对话框的地方。
FragmentManager fragmentManager = getFragmentManager();
categoryDialog.setTargetFragment(this,1);
categoryDialog.show(fragmentManager, "dialog");
where categoryDialog是我的DialogFragment,我想调用这之后,在你的DialogFragment的实现中放置这段代码,你在意图中设置你的数据。resultCode的值为1,可以设置或使用system Defined。
Intent intent = new Intent();
intent.putExtra("listdata", stringData);
getTargetFragment().onActivityResult(getTargetRequestCode(), resultCode, intent);
getDialog().dismiss();
现在回到调用片段并实现该方法。在if条件中使用resultCode和requestCode检查数据有效性或结果成功。
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
//do what ever you want here, and get the result from intent like below
String myData = data.getStringExtra("listdata");
Toast.makeText(getActivity(),data.getStringExtra("listdata"),Toast.LENGTH_SHORT).show();
}
不同的方法,允许一个片段与它的活动通信:
1)在片段中定义一个公共接口,并为其创建一个变量
public OnFragmentInteractionListener mCallback;
public interface OnFragmentInteractionListener {
void onFragmentInteraction(int id);
}
2)将活动转换为片段中的mCallback变量
try {
mCallback = (OnFragmentInteractionListener) getActivity();
} catch (Exception e) {
Log.d(TAG, e.getMessage());
}
3)在你的活动中实现监听器
public class MainActivity extends AppCompatActivity implements DFragment.OnFragmentInteractionListener {
//your code here
}
4)在活动中覆盖OnFragmentInteraction
@Override
public void onFragmentInteraction(int id) {
Log.d(TAG, "received from fragment: " + id);
}
更多信息:https://developer.android.com/training/basics/fragments/communicating.html
使用这个AppDialog类既可以将数据传递到DialogFragment,也可以从中获取结果。
详细解释:
Premise - Fragments get destroyed and recreated on config changes. View models hang around. When using a Dialog, it is recommended to wrap it in DialogFragment so that when the user rotates device and changes orientation the Dialog will not unexpectedly disappear (the DialogFragment will re-create it and re-display it). Limitation (hence this question) - The way the DialogFragment works is it takes a class that it will need to re-instantiate on configuration changes - that means one can't have constructor parameters to the subclass to pass parameters, and typically one needs to make custom callbacks through a view model to pass back result of dialog. That typically means a new subclass for every dialog. The solution - To help with all this, this custom AppDialog fragment comes to the rescue - the parameters are stored in-memory (similar to view model, you can think of it as a tiny custom view model that holds T in memory and uses it to re-create the dialog on config changes) until the dialog fragment is dismissed. The proper way to call back would be through a view model. If the fragment that shows the AppDialog, then you probably already have a view model and you can reference it from the lambda used to create the dialog - that means additional strong reference to the view model until the dialog fragment is dismissed. Example - see the examples where a simple Dialog is refactored to use this AppDialog utility class to both receive a parameter and do a callback to viewModel to notify of result.
helper类:
class AppDialog<T>: DialogFragment() {
companion object {
fun<T> buildDialog(params: T? = null, builder: AppDialogLambda<T>): AppDialog<T> {
// Setup arguments
val args = Bundle()
args.putInt("key", pushDialogArgs(params, builder))
// Instantiate
val fragment = AppDialog<T>()
fragment.arguments = args
return fragment
}
// --------------------
// Dialog Arguments
private var lastKey: Int = 0
private val dialogArgs = mutableMapOf<Int, Pair<Any?, AppDialogLambda<*>>>()
private fun pushDialogArgs(params: Any?, builder: AppDialogLambda<*>): Int {
dialogArgs[lastKey] = params to builder
return lastKey++
}
private fun getDialogArgs(key: Int): Pair<Any?, AppDialogLambda<*>> {
return dialogArgs[key]!!
}
private fun deleteDialogArgs(key: Int) {
dialogArgs.remove(key)
}
}
override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
// Get arguments
val argKey = requireArguments().getInt("key")
val (params, builder) = getDialogArgs(argKey)
// We are getting back our arguments we passed AppDialog.buildDialog and
// the type is guaranteed to be the same. Silence this warning
@Suppress("UNCHECKED_CAST")
return (builder as AppDialogLambda<T>)(this, params as T?)
}
override fun onDismiss(dialog: DialogInterface) {
super.onDismiss(dialog)
val argKey = requireArguments().getInt("key")
deleteDialogArgs(argKey)
}
}
示例用法(之后):
val info = mapOf("message" to "${error.description}\n\nPlease check your Internet connection and try again.")
AppDialog.buildDialog(info) { fragment, params ->
fragment.isCancelable = false // since we are in a DialogFragment
AlertDialog.Builder(fragment.context)
.setTitle("Terms Of Service Failed To Load")
.setMessage(params!!["message"])
.setPositiveButton("Retry") { _, _ ->
// Update the view model instead of calling UserTOSFragment directly
// as the fragment may be destroyed and recreated
// on configuration changes. The viewModel will stay alive.
viewModel.onTermsOfServiceReload()
}
.setNegativeButton("Cancel") { _, _ ->
viewModel.onTermsOfServiceDeclined()
fragment.findNavController().popBackStack()
}.create()
}.show(parentFragmentManager, "TOS Failed Dialog")
用法示例(前): 如果不使用DialogFragment(为了说明目的,不要这样做,这是不好的做法,因为对话框将在配置更改时被销毁),则UserTOSFragment中的代码。kt -用于在重试时直接调用UserTOSFragment.loadContent()的注释代码。在上面的例子中,这必须重写为调用viewModel.onTermsOfServiceDeclined():
AlertDialog.Builder(context)
.setTitle("Terms Of Service Failed To Load")
.setMessage("${error.description}\n\nPlease check your Internet connection and try again.")
.setPositiveButton("Retry") { _, _ ->
loadContent()
}
.setCancelable(false)
.setNegativeButton("Cancel") { _, _ ->
viewModel.onTermsOfServiceDeclined()
findNavController().popBackStack()
}
.show()
关于一个对话片段
class AbcDialogFragment(private val ondata: (data: String) -> Unit) : DialogFragment() {}
显示片段/活动对话框的代码
val abcDialogFragment = AbcDialogFragment(ondata = {data-> })
abcDialogFragment.show(requireActivity().supportFragmentManager, "TAG")
在对话片段中,你可以在对话片段关闭或任何点击监听器时调用onData。