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

如果你想发送参数并从第二个片段接收结果,你可以使用fragment。setargarguments来完成这个任务

static class FirstFragment extends Fragment {
    final Handler mUIHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case 101: // receive the result from SecondFragment
                Object result = msg.obj;
                // do something according to the result
                break;
            }
        };
    };

    void onStartSecondFragments() {
        Message msg = Message.obtain(mUIHandler, 101, 102, 103, new Object()); // replace Object with a Parcelable if you want to across Save/Restore
                                                                               // instance
        putParcelable(new SecondFragment(), msg).show(getFragmentManager().beginTransaction(), null);
    }
}

static class SecondFragment extends DialogFragment {
    Message mMsg; // arguments from the caller/FirstFragment

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onViewCreated(view, savedInstanceState);
        mMsg = getParcelable(this);
    }

    void onClickOK() {
        mMsg.obj = new Object(); // send the result to the caller/FirstFragment
        mMsg.sendToTarget();
    }
}

static <T extends Fragment> T putParcelable(T f, Parcelable arg) {
    if (f.getArguments() == null) {
        f.setArguments(new Bundle());
    }
    f.getArguments().putParcelable("extra_args", arg);
    return f;
}
static <T extends Parcelable> T getParcelable(Fragment f) {
    return f.getArguments().getParcelable("extra_args");
}

其他回答

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

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();
    }

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()

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

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。