如何在片段之间传递值

我对使用片段很陌生。

我只是试图构建一个使用片段的简单示例应用程序。我的情况是，我有两个活动，每个活动中都有一个片段。第一个片段具有一个edittext和一个按钮。第二个片段具有textview。当我在edittext中输入名称并单击按钮时，第二个片段中的textview应该显示在第一个片段的edittext中输入的名称。

我能够将值从第一个片段发送到其活动，然后从该活动发送到第二个活动。现在，我如何在第二个片段中使用此值。

这是Java代码:::

package com.example.fragmentexample;

import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class Fragment_1 extends Fragment{

    OnFragmentChangedListener mCallback;

    // Container Activity must implement this interface
    public interface OnFragmentChangedListener {
        public void onButtonClicked(String name);
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);

        // This makes sure that the container activity has implemented
        // the callback interface. If not, it throws an exception
        try {
            mCallback = (OnFragmentChangedListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement OnHeadlineSelectedListener");
        }
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        // TODO Auto-generated method stub      

        View view = inflater.inflate(R.layout.fragment_fragment_1, container, false);

        final EditText edtxtPersonName_Fragment = (EditText) view.findViewById(R.id.edtxtPersonName);
        Button btnSayHi_Fragment = (Button) view.findViewById(R.id.btnSayHi);

        btnSayHi_Fragment.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                String name = edtxtPersonName_Fragment.getText().toString();

                FragmentManager fm = getFragmentManager();
                Fragment_2 f2 = (Fragment_2) fm.findFragmentById(R.id.fragment_content_2);

                Activity activity = getActivity();

                if(activity != null)
                {
                    Toast.makeText(activity, "Say&ing Hi in Progress...", Toast.LENGTH_LONG).show();
                }


                if(f2 != null && f2.isInLayout())
                {
                    f2.setName(name);
                }
                else
                {
                    mCallback.onButtonClicked(name);
                }
            }
        });

        return view;


    }

}

MainActivity.Java

package com.example.fragmentexample;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;

import android.view.Choreographer.FrameCallback;
import android.view.Menu;

public class MainActivity extends Activity implements Fragment_1.OnFragmentChangedListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);     
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    @Override
    public void onButtonClicked(String name) {
        // TODO Auto-generated method stub

        Intent i = new Intent(this, SecondActivity.class);
        i.putExtra("", name);
        startActivity(i);
    }

}

SecondActivity.Java

package com.example.fragmentexample;

import android.app.Activity;
import android.os.Bundle;

public class SecondActivity extends Activity{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_second);

        Bundle b = getIntent().getExtras();

        Fragment_2 f2 = new Fragment_2();
        f2.setArguments(b);
    }
}

Fragment_2.Java

package com.example.fragmentexample;

import android.app.Activity;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class Fragment_2 extends Fragment{

    View view;
    TextView txtName;


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        // TODO Auto-generated method stub

        view = inflater.inflate(R.layout.fragment_fragment_2, container, false);

            // Exception at this line
        String name = getArguments().getString("message");
        txtName = (TextView) view.findViewById(R.id.txtViewResult);
        txtName.setText(name);

        return view;
    }

    @Override
    public void onAttach(Activity activity) {
        // TODO Auto-generated method stub
        super.onAttach(activity);       
    }

    public void setName(String name)
    {   
        txtName.setText("Hi " + name);
    }

}

我收到以下异常:::

04-16 18:10:24.573: E/AndroidRuntime(713): FATAL EXCEPTION: main
04-16 18:10:24.573: E/AndroidRuntime(713): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.fragmentexample/com.example.fragmentexample.SecondActivity}: android.view.InflateException: Binary XML file line #8: Error inflating class fragment
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1815)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1831)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.app.ActivityThread.access$500(ActivityThread.java:122)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1024)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.os.Handler.dispatchMessage(Handler.java:99)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.os.Looper.loop(Looper.java:132)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.app.ActivityThread.main(ActivityThread.java:4123)
04-16 18:10:24.573: E/AndroidRuntime(713):  at java.lang.reflect.Method.invokeNative(Native Method)
04-16 18:10:24.573: E/AndroidRuntime(713):  at java.lang.reflect.Method.invoke(Method.java:491)
04-16 18:10:24.573: E/AndroidRuntime(713):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
04-16 18:10:24.573: E/AndroidRuntime(713):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
04-16 18:10:24.573: E/AndroidRuntime(713):  at dalvik.system.NativeStart.main(Native Method)
04-16 18:10:24.573: E/AndroidRuntime(713): Caused by: android.view.InflateException: Binary XML file line #8: Error inflating class fragment
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:688)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.view.LayoutInflater.rInflate(LayoutInflater.java:724)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.view.LayoutInflater.inflate(LayoutInflater.java:479)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.view.LayoutInflater.inflate(LayoutInflater.java:391)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.view.LayoutInflater.inflate(LayoutInflater.java:347)
04-16 18:10:24.573: E/AndroidRuntime(713):  at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:223)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.app.Activity.setContentView(Activity.java:1786)
04-16 18:10:24.573: E/AndroidRuntime(713):  at com.example.fragmentexample.SecondActivity.onCreate(SecondActivity.java:13)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.app.Activity.performCreate(Activity.java:4397)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779)
04-16 18:10:24.573: E/AndroidRuntime(713):  ... 11 more
04-16 18:10:24.573: E/AndroidRuntime(713): Caused by: java.lang.NullPointerException
04-16 18:10:24.573: E/AndroidRuntime(713):  at com.example.fragmentexample.Fragment_2.onCreateView(Fragment_2.java:24)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:754)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:956)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.app.FragmentManagerImpl.addFragment(FragmentManager.java:1035)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.app.Activity.onCreateView(Activity.java:4177)
04-16 18:10:24.573: E/AndroidRuntime(713):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:664)
04-16 18:10:24.573: E/AndroidRuntime(713):  ... 21 more

如何从SecondActivity.java中的包中获取值到Fragment_2.Java？

步骤1。将数据从片段发送到活动

Intent intent = new Intent(getActivity().getBaseContext(),
                        TargetActivity.class);
                intent.putExtra("message", message);
                getActivity().startActivity(intent);

第2步：在“活动”中接收此数据：

Intent intent = getIntent();
String message = intent.getStringExtra("message");

第三步。按照常规方法将数据从活动发送到另一个活动

Intent intent = new Intent(MainActivity.this,
                        TargetActivity.class);
                intent.putExtra("message", message);
                startActivity(intent);

步骤4以在活动中接收此数据

     Intent intent = getIntent();
  String message = intent.getStringExtra("message");

步骤5.从Activity中，您可以将数据发送到Fragment，意图是：

Bundle bundle=new Bundle();
bundle.putString("message", "From Activity");
  //set Fragmentclass Arguments
Fragmentclass fragobj=new Fragmentclass();
fragobj.setArguments(bundle);

并在Fragment onCreateView方法中接收片段：

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
    Bundle savedInstanceState) {
          String strtext=getArguments().getString("message");

    return inflater.inflate(R.layout.fragment, container, false);
    }

如开发者网站所述

通常，您会希望一个Fragment与另一个Fragment进行通信，例如，根据用户事件更改内容。所有片段到片段的通信都是通过关联的活动完成的。两个片段永远不要直接通信。

片段之间的通信应通过相关的活动进行。

让我们具有以下组件：

活动托管片段并允许片段通信

片段发送数据的第一个片段

FragmentB第二个片段，它将接收来自FragmentA的数据

FragmentA的实现是：

public class FragmentA extends Fragment 
{
    DataPassListener mCallback;
    
    public interface DataPassListener{
        public void passData(String data);
    }

    @Override
    public void onAttach(Context context) 
    {
        super.onAttach(context);
        // This makes sure that the host activity has implemented the callback interface
        // If not, it throws an exception
        try 
        {
            mCallback = (OnImageClickListener) context;
        }
        catch (ClassCastException e) 
        {
            throw new ClassCastException(context.toString()+ " must implement OnImageClickListener");
        }
    }
    
    public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) 
    {
        // Suppose that when a button clicked second FragmentB will be inflated
        // some data on FragmentA will pass FragmentB
        // Button passDataButton = (Button).........
        
        passDataButton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                if (view.getId() == R.id.passDataButton) {
                    mCallback.passData("Text to pass FragmentB");
                }
            }
        });
    }
}

MainActivity的实现是：

public class MainActivity extends ActionBarActivity implements DataPassListener{
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        if (findViewById(R.id.container) != null) {
            if (savedInstanceState != null) {
                return;
            }
            getFragmentManager().beginTransaction()
                    .add(R.id.container, new FragmentA()).commit();
        }
    }
    
    @Override
    public void passData(String data) {
        FragmentB fragmentB = new FragmentB ();
        Bundle args = new Bundle();
        args.putString(FragmentB.DATA_RECEIVE, data);
        fragmentB .setArguments(args);
        getFragmentManager().beginTransaction()
            .replace(R.id.container, fragmentB )
            .commit();
    }
}

FragmentB的实现是：

public class FragmentB extends Fragment{
    final static String DATA_RECEIVE = "data_receive";
    TextView showReceivedData;
    
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_B, container, false);
        showReceivedData = (TextView) view.findViewById(R.id.showReceivedData);
    }
    
    @Override
    public void onStart() {
        super.onStart();
        Bundle args = getArguments();
        if (args != null) {
            showReceivedData.setText(args.getString(DATA_RECEIVE));
        }
    }
}

我希望这个能帮上忙..

//在Fragment_1.java中

Bundle bundle = new Bundle();
bundle.putString("key","abc"); // Put anything what you want

Fragment_2 fragment2 = new Fragment_2();
fragment2.setArguments(bundle);

getFragmentManager()
      .beginTransaction()
      .replace(R.id.content, fragment2)
      .commit();

//在Fragment_2.java中

Bundle bundle = this.getArguments();

if(bundle != null){
     // handle your code here.
}

希望对您有帮助。

从开发者网站：

通常，您会希望一个Fragment与另一个Fragment进行通信，例如，根据用户事件更改内容。所有片段到片段的通信都是通过关联的活动完成的。两个片段永远不要直接通信。

您可以借助其活动在片段之间进行通信。您可以使用此方法在活动和片段之间进行通信。

请也检查此链接。

首先，所有答案都是正确的，您可以使用传递自定义对象以外的数据Intent。如果要传递自定义对象，则必须实现Serialazable或Parcelable传递给自定义对象类。我认为这太复杂了...

因此，如果您的项目很简单，请尝试使用DataCache。这提供了传递数据的超级简单方法。 参考： Github项目CachePot

1-将其设置为将发送数据的视图或活动或片段

DataCache.getInstance().push(obj);

2-如下所示获取数据

public class MainFragment extends Fragment
{
    private YourObject obj;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

        obj = DataCache.getInstance().pop(YourObject.class);

    }//end onCreate()
}//end class MainFragment

可以通过使用Android体系结构组件（例如ViewModel和LiveData）来实现在片段之间传递数据的最新解决方案。使用此解决方案，您无需定义用于通信的接口，并且可以获得使用ViewModel的优势，例如由于配置更改而产生的数据存活。

在此解决方案中，通信中涉及的片段共享与其活动生命周期相关联的同一viewmodel对象。视图模型对象包含livedata对象。一个片段设置要在livedata对象上传递的数据，第二个片段观察者对livedata进行更改并接收数据。

这是完整的示例http://www.zoftino.com/passing-data-between-android-fragments-using-viewmodel

在片段之间传递参数。 回答这个问题还为时已晚，但可以帮助某人！ Fragment_1.java

Bundle i = new Bundle(); 
            i.putString("name", "Emmanuel");

            Fragment_1 frag = new Fragment_1();
            frag.setArguments(i);
            FragmentManager fragmentManager = getFragmentManager();
            fragmentManager.beginTransaction()
                    .replace(R.id.content_frame
                            , new Fragment_2())
                    .commit();

然后在你的Fragment_2.java，你可以在你的内获得PARAMATERS常onActivityCreated 如

 Intent intent = getActivity().getIntent();
    if (intent.getExtras() != null) {
        String name =intent.getStringExtra("name");
    }

我认为解决此问题的一种好方法是使用自定义界面。

假设您在同一活动中有两个片段（A和B），并且您想要将数据从A发送到B。

介面

public interface OnDataSentListener{
    void onDataSent(Object data);
}

活动：

    public class MyActivity extends AppCompatActivity{

            private OnDataSentListener onDataSentListener;

            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_activity);

                FragmentTransaction trans = getFragmentManager().beginTransaction();

                FragmentA fa = new FragmentA();
                FragmentB fb = new FragmentB();

               fa.setOnDataSentListener(new Listeners.OnDataSentListener() {
                    @Override
                    public void onDataSent(Object data) {
                         if(onDataSentListener != null)  onDataSentListener.onDataSent(data);
                    }
               });

                transaction.add(R.id.frame_a, fa);
                transaction.add(R.id.frame_b, fb);

                transaction.commit();
            }

            public void setOnDataSentListener(OnDataSentListener listener){
                this.onDataSentListener = listener;
            }
        }

片段A：

public class FragmentA extends Fragment{

    private OnDataSentListener onDataSentListener;

    private void sendDataToFragmentB(Object data){
        if(onDataSentListener != null) onDataSentListener.onDataSent(data);
    }

    public void setOnDataSentListener(OnDataSentListener listener){
        this.onDataSentListener = listener;
    }
}

片段B：

public class FragmentB extends Fragment{

    private void initReceiver(){
        ((MyActivity) getActivity()).setOnDataSentListener(new OnDataSentListener() {
            @Override
            public void onDataSent(Object data) {
                //Here you receive the data from fragment A
            }
        });
    }
}

在片段之间进行通信是相当复杂的（我发现听众的概念很难实施）。

通常使用“事件总线”来抽象这些通信，这是一个第三方库，可以为您处理这种通信。

“ Otto”是经常用于执行此操作的工具，可能值得研究：http : //square.github.io/otto/

将数据从片段传递到另一个片段

• 从第一个片段

  // Set data to pass
  MyFragment fragment = new MyFragment(); //Your Fragment
  Bundle bundle = new Bundle();
  bundle.putInt("year", 2017)  // Key, value
  fragment.setArguments(bundle); 
  // Pass data to other Fragment
  getFragmentManager()
   .beginTransaction()
   .replace(R.id.content, fragment)
   .commit(); 

• 在第二片段

  @Override
  public void onCreate(@Nullable Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
  
       Bundle bundle = this.getArguments();
       if (bundle != null) {
           Int receivedYear = bundle.getInt("year", ""); // Key, default value
       } 
  }

这个简单的实现有助于以一种简单的方式在片段之间传递数据。认为您要将数据从“ Frgment1”传递到“ Fragment2”

在Fragment1中（设置要发送的数据）

 Bundle bundle = new Bundle();
 bundle.putString("key","Jhon Doe"); // set your parameteres

 Fragment2 nextFragment = new Fragment2();
 nextFragment.setArguments(bundle);

 FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
 fragmentManager.beginTransaction().replace(R.id.content_drawer, nextFragment).commit();

在Fragment2 onCreateView方法中（获取参数）

String value = this.getArguments().getString("key");//get your parameters
Toast.makeText(getActivity(), value+" ", Toast.LENGTH_LONG).show();//show data in tost

科特林方式

使用SharedViewModel官方ViewModel 文档中的建议

一个活动中的两个或更多片段需要相互通信是很常见的。想象一下主从片段的一种常见情况，您有一个片段，其中用户从列表中选择一个项目，另一个片段显示了所选项目的内容。这种情况绝不容易，因为两个片段都需要定义一些接口描述，并且所有者活动必须将两者绑定在一起。此外，两个片段都必须处理另一个片段尚未创建或不可见的情况。

可以通过使用ViewModel对象解决此常见的痛点。这些片段可以使用其活动范围共享ViewModel来处理此通信

首先实现fragment-ktx，以更轻松地实例化您的视图模型

dependencies {
    implementation "androidx.fragment:fragment-ktx:1.2.2"
} 

然后，您只需要将要与其他片段共享的数据放入视图模型中

class SharedViewModel : ViewModel() {
    val selected = MutableLiveData<Item>()

    fun select(item: Item) {
        selected.value = item
    }
}

然后，最后，只需在每个片段中实例化viewModel，然后selected从要设置数据的片段中设置的值

片段A

class MasterFragment : Fragment() {

    private val model: SharedViewModel by activityViewModels()

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        itemSelector.setOnClickListener { item ->
        model.select(item)
      }

    }
}

然后，在Fragment目的地监听此值

片段B

 class DetailFragment : Fragment() {

        private val model: SharedViewModel by activityViewModels()

        override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
            super.onViewCreated(view, savedInstanceState)
            model.selected.observe(viewLifecycleOwner, Observer<Item> { item ->
                // Update the UI
            })
        }
    }

您也可以采用相反的方式

100％有效的解决方案：（如果您有帮助，请不要忘记投票）

在您的第一个片段中放入以下代码：

    editprofile.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {

                    Fragment_editprofile Fragment = new Fragment_editprofile();
.
.
.
.
.


                Fragment.getintentdetails(tv_name.getText().toString(),
                            tv_mob.getText().toString(), tv_email.getText().toString(), tv_dob.getText().toString(),
                            tv_gender.getText().toString(), photointent);

                }
            });

在第二个片段中，制作如下方法：

public void getintentdetails(String name, String mobile, String email, String dob, String gender,
                                 String photointent) {

        this.name_str= name;
        this.mob_str= mobile;
        this.email_str= email;
        this.dob_str= dob;
        this.gender_str= gender;
        this.photo_str= photointent;

    }

然后在类级别定义一个变量：

String name_str, mob_str, dob_str, photo_str, email_str, gender_str;

然后在第二个片段中制作另一个方法来设置值：

  setexistingdetails();


private void setexistingdetails() {

        if(!name_str.equalsIgnoreCase(""))
            (et_name).setText(name_str);
        if(!mob_str.equalsIgnoreCase(""))
            et_mobile.setText(mob_str);
        if(!email_str.equalsIgnoreCase(""))
            email_et.setText(email_str);
        if(!dob_str.equalsIgnoreCase(""))
            dob_et.setText(dob_str);
        if(!gender_str.equalsIgnoreCase("")){
            if (gender_str.equalsIgnoreCase("m")){
                male_radio.setChecked(true);
            }else {
                female_radio.setChecked(true);
            }
        }
        if(!photo_str.equalsIgnoreCase("")){
            try {
                Picasso.get().load(Const.BASE_PATH+"include/sub-domain/GENIUS/"+photo_str).into(adminpropic_edit);
            } catch (Exception e) {            }
        }
    }

您可以通过Arnav Rao清除的ViewModel和Live Data来实现您的目标。现在我举一个例子来更清楚地清除它。

首先，将假设ViewModel命名为SharedViewModel.java。

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;
    }
}

然后，源片段就是MasterFragment.java我们要从中发送数据的位置。

public class MasterFragment extends Fragment {
    private SharedViewModel model;

    public void onViewCreated(@NonNull View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        model = new ViewModelProvider(requireActivity()).get(SharedViewModel.class);
        itemSelector.setOnClickListener(item -> {

            // Data is sent

            model.select(item);
        });
    }
}

最后，目标片段是DetailFragment.java我们要接收数据的位置。

public class DetailFragment extends Fragment {

    public void onViewCreated(@NonNull View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        SharedViewModel model = new ViewModelProvider(requireActivity()).get(SharedViewModel.class);
        model.getSelected().observe(getViewLifecycleOwner(), { item ->

           // Data is received 

        });
    }
}

好了，在这里进行了大量的挖掘之后，我找到了一个简单的解决方案，实际上您永远不应该将数据从片段传递到片段，这总是一个坏主意，您可以将数据从片段A传递到活动，并从片段B的活动获取数据。

For Example
//fragment A
//your method that will be called in Main Activity for getting data from this fragment
public List<customDataModel> getlist(){
return mlist; //your custom list 
}
buttonopen.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //before calling  your new fragment, send a Broadcast signal to your main activity
 mContext.sendBroadcast(new Intent("call.myfragment.action"));
//here you are now changing the fragment
Fragment fragment1 = new VolunteerListDetailsFragment();

            FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
            ft.replace(R.id.content_frame, fragment1);
            ft.commit();
        }
    });

//在主要活动中

this.registerReceiver(mBroadcastReceiver, new IntentFilter("call.myfragment.action"));//this line should be in your onCreate method
   BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {

    @Override
    public void onReceive(Context context, Intent intent) {
//init the fragment A
FragmenA fragment =
                (FragmentA) getSupportFragmentManager().findFragmentById(R.id.content_frame);
        mlistdetails = fragment.getlist();//this is my method in fragmentA which is retuning me a custom list, init this list type in top of on create fragment


    }
};
//here you are creating method that is returning the list that you just recieved From fragmentA
public List<customDataModel> getcustomlist(){
return mlistdetails; //you are returning the same list that you recived from fragmentA
}

//现在在FragmentB中

 public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    View rootView = (View) inflater.inflate(R.layout.vol_listdetails, container, false);

    mlistdetails=((MainActivity)getActivity()).getcustomlist();//here you are calling the method that you have created in Main Activity

    Toast.makeText(getActivity().getApplicationContext(), mlistdetails.get(0).getItemqty(), Toast.LENGTH_SHORT).show();
    return rootView;

}

我对像我这样的初学者来说确实很容易。.我在activity_main.xml中创建了一个textview，

id=index
visibility=invisible

然后我从第一个片段得到这个textview

index= (Textview) getActivity().findviewbyid(R.id.index)
index.setText("fill me with the value")

然后在第二个片段中我得到值

index= (Textview) getActivity().findviewbyid(R.id.index)
String get_the_value= index.getText().toString();

希望能帮助到你！