How to pass values between Fragments

Question

I am pretty new to using Fragments.

I am just trying to build a simple sample application that uses Fragments. My scenario is, I have two activities with one fragment inside each activity. The first fragment has an edittext and a button. The second fragment has a textview. When i enter a name in the edittext and click on the button, the textview in the second fragment should display the name entered in the edittext of the first fragment.

I was able to send the value from first fragment to its activity and then from that activity to second activity. Now how do i use this value inside the second fragment.

Here is the Java code :::

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);
    }

}

I get the following exception :::

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

How do I get the value from the bundle in SecondActivity.java to the Fragment_2.Java?

Answer 1

From Developers website:

Often you will want one Fragment to communicate with another, for example to change the content based on a user event. All Fragment-to-Fragment communication is done through the associated Activity. Two Fragments should never communicate directly.

You can communicate among fragments with the help of its Activity. You can communicate among activity and fragment using this approach.

Please check this link also.

Answer 2

I think a good way to solve this problem is to use a custom interface.

Lets say you have two fragments (A and B) which are inside of the same activity and you want to send data from A to B.

Interface :

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

Activity:

    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;
            }
        }

Fragment 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;
    }
}

Fragment 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
            }
        });
    }
}

Answer 3

step 1.to send data from fragment to activity

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

step 2.to receive this data in Activity:

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

step 3. to send data from activity to another activity follow normal approach

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

step 4 to receive this data in activity

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

Step 5. From Activity you can send data to Fragment with intent as:

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

and to receive in fragment in Fragment onCreateView method:

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

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

Answer 4

// In Fragment_1.java

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();

// In Fragment_2.java

Bundle bundle = this.getArguments();

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

Hope this help you.

Answer 5

First all answers are right, you can pass the data except custom objects by using Intent. If you want to pass the custom objects, you have to implement Serialazable or Parcelable to your custom object class. I thought it's too much complicated...

So if your project is simple, try to use DataCache. That provides super simple way for passing data. Ref: Github project CachePot

1- Set this to View or Activity or Fragment which will send data

DataCache.getInstance().push(obj);

2- Get data anywhere like below

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

Answer 6

Communicating between fragments is fairly complicated (I find the listeners concept a little challenging to implement).

It is common to use a 'Event Bus" to abstract these communications. This is a 3rd party library that takes care of this communication for you.

'Otto' is one that is used often to do this, and might be worth looking into: http://square.github.io/otto/