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

只是把它作为一个选项(因为还没有人提到它)——你可以使用像Otto这样的事件总线。 所以在对话中你要这样做:

bus.post(new AnswerAvailableEvent(42));

并让你的调用者(Activity或Fragment)订阅它:

@Subscribe public void answerAvailable(AnswerAvailableEvent event) {
   // TODO: React to the event somehow!
}

其他回答

有一种更简单的方法来接收来自DialogFragment的结果。

首先,在你的Activity、Fragment或FragmentActivity中,你需要添加以下信息:

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    // Stuff to do, dependent on requestCode and resultCode
    if(requestCode == 1) { // 1 is an arbitrary number, can be any int
         // This is the return result of your DialogFragment
         if(resultCode == 1) { // 1 is an arbitrary number, can be any int
              // Now do what you need to do after the dialog dismisses.
         }
     }
}

requestCode基本上是你调用的DialogFragment的int标签,我马上会展示它是如何工作的。resultCode是你从DialogFragment发送回来的代码,告诉你当前正在等待的Activity、Fragment或FragmentActivity发生了什么。

下一段代码是对DialogFragment的调用。这里有一个例子:

DialogFragment dialogFrag = new MyDialogFragment();
// This is the requestCode that you are sending.
dialogFrag.setTargetFragment(this, 1);     
// This is the tag, "dialog" being sent.
dialogFrag.show(getFragmentManager(), "dialog");

用这三行你声明了你的DialogFragment,设置了一个requestCode(它将调用onActivityResult(…)一旦对话框被驳回,然后你就会显示对话框。就是这么简单。

现在,在你的DialogFragment中,你只需要在dismiss()之前直接添加一行,这样你就可以将resultCode发送回onActivityResult()。

getTargetFragment().onActivityResult(getTargetRequestCode(), resultCode, getActivity().getIntent());
dismiss();

就是这样。注意,resultCode被定义为int resultCode,我已经设置为resultCode = 1;在这种情况下。

就是这样,你现在可以把你的DialogFragment的结果发送回你调用的Activity, Fragment,或者FragmentActivity。

另外,看起来这些信息之前已经发布了,但是没有给出足够的例子,所以我想我应该提供更多的细节。

编辑06.24.2016 我为上面的误导性代码道歉。但是你肯定不能接收回活动的结果,就像这行:

dialogFrag.setTargetFragment(this, 1);

设置目标片段而不是活动。为了做到这一点,你需要实现一个interfacecommunator。

在你的DialogFragment中设置一个全局变量

public InterfaceCommunicator interfaceCommunicator;

创建一个公共函数来处理它

public interface InterfaceCommunicator {
    void sendRequestCode(int code);
}

然后,当你准备好在DialogFragment完成运行时将代码发送回Activity时,你只需在你dismiss()之前添加一行;你的DialogFragment:

interfaceCommunicator.sendRequestCode(1); // the parameter is any int code you choose.

现在在你的活动中你必须做两件事,第一件事是删除那一行不再适用的代码:

dialogFrag.setTargetFragment(this, 1);  

然后实现接口,一切都完成了。你可以通过在类顶部的implements子句中添加以下一行来做到这一点:

public class MyClass Activity implements MyDialogFragment.InterfaceCommunicator

然后@Override activity中的函数,

@Override
public void sendRequestCode(int code) {
    // your code here
}

使用这个接口方法就像使用onActivityResult()方法一样。除了接口方法是针对DialogFragments,另一个是针对Fragments。

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。

我很惊讶地看到,没有人建议使用本地广播进行DialogFragment到Activity的通信!我发现它比其他建议更简单、更清晰。本质上,您为您的Activity注册侦听广播,并从您的DialogFragment实例发送本地广播。简单。有关如何设置它的一步一步的指南,请参见这里。

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()

在Kotlin

    // My DialogFragment
class FiltroDialogFragment : DialogFragment(), View.OnClickListener {
    
    var listener: InterfaceCommunicator? = null

    override fun onAttach(context: Context?) {
        super.onAttach(context)
        listener = context as InterfaceCommunicator
    }

    interface InterfaceCommunicator {
        fun sendRequest(value: String)
    }   

    override fun onClick(v: View) {
        when (v.id) {
            R.id.buttonOk -> {    
        //You can change value             
                listener?.sendRequest('send data')
                dismiss()
            }
            
        }
    }
}

//我的活动

class MyActivity: AppCompatActivity(),FiltroDialogFragment.InterfaceCommunicator {

    override fun sendRequest(value: String) {
    // :)
    Toast.makeText(this, value, Toast.LENGTH_LONG).show()
    }
}
 

我希望它服务,如果你可以改进,请编辑它。 我的英语不太好