Communication Between Fragments In Android

Here I will explain the communication between fragments in Android. The following is a brief description of the  task that I am going to show you.

 

I have an Activity with two fragments, lets name that fragments to FragmentA and Fragment B. FragmentA contains a Button and FragmentB contains a textview.

Each time the user click on the Button of FragmentA then the textview in the FragmentB will updates its text like "this button is clicked <counter> times".

This is the task I am going to show you.

 

For this first create FragmentA and its Layout,

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:background="@android:color/darker_gray" android:layout_height="match_parent">
    <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Click Me" android:layout_margin="20dp" android:id="@+id/button" android:layout_gravity="center_horizontal" />
</LinearLayout>

The FragmentA contains a Button and in the java code please load the xml file in onCreateView();
 

Now create FragmentB and its Layout,

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:background="@android:color/white" android:layout_height="match_parent">
    <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_margin="20dp" android:textAppearance="?android:attr/textAppearanceLarge" android:text="Large Text" android:id="@+id/textView" android:layout_gravity="center_horizontal" />
</LinearLayout>

FragmentB contains a Textview only. load this layout to FragmetB class on the onCreateView() 

 

Now create the main part of the task that is communicator  Interface.

public interface Communicator
{
    public void clicked(String text);
}

Now create the MainActivity that implement Communicator Interface,

public class MainActivity extends Activity implements Communicator
{
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    @Override
    public void clicked(String text)
    {
        FragmentB b = (FragmentB) getFragmentManager().findFragmentById(R.id.fragment2);
        b.chageText(text);
    }
}

The clicked method will call another method named changeText(String) in Fragment B. Now we need to notify the communicator Interface when Button in FragmentA is clicked and create a method chageText(String) in FragmentB.

 

Now create Button Click Event in FragmentA. This is how the FragmentA will looks like,

public class FragmentA extends Fragment
{
    private int counter = 0;
    private Communicator comm = null;
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        return inflater.inflate(R.layout.fragment_a, container, false);
    }
    @Override
    public void onActivityCreated(Bundle savedInstanceState)
    {
        super.onActivityCreated(savedInstanceState);
        Button button = (Button) getActivity().findViewById(R.id.button);
        comm = (Communicator) getActivity();
        button.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View view)
            {
                counter++;
                comm.clicked("This button is clicked " + counter + " times");
            }
        });
    }
}

On the onActivityCreated() we are initialising the communicator with the FragmentA, and in the button click we are firing the interface method()

 

Now Create the FragmentB,

public class FragmentB extends Fragment
{
    private TextView textView = null;
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        return inflater.inflate(R.layout.fragment_b, container, false);
    }
    @Override
    public void onActivityCreated(Bundle savedInstanceState)
    {
        super.onActivityCreated(savedInstanceState);
        textView = (TextView) getActivity().findViewById(R.id.textView);
    }
    public void chageText(String data)
    {
        textView.setText(data);
    }
}

There will be a method named chageText to change the content of textView in FragmentB. This is the way in which the fragments communicate in Android.

The out put will looks as follows,



 

Read more articles on Android:

• Push Notification To Android Mobile Using GCM (Google Cloud Messaging)
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