How to use Fragments in Android

You need to add an empty public constructor to your Fragments, like it says in the stack trace:

public class Fragment_2 extends Fragment{

    public Frament_2() {
        //BLAH!
    }

    // The rest of your code

}

Okie... Finally found a solution. Probably, it wasn't much of a change.

Check out the code below...

activity_main.XML

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <fragment
        android:id="@+id/fragment_content_1"
        android:name="com.example.fragmentexample.Fragment_1"
        android:layout_width="0dip"
        android:layout_weight="0.50"
        android:layout_height="fill_parent" >
    </fragment>

    <fragment
        android:id="@+id/fragment_content_2"
        android:name="com.example.fragmentexample.Fragment_2"
        android:layout_width="0dip"
        android:layout_weight="0.50"
        android:layout_height="fill_parent" >

        <!-- Preview: layout=@layout/fragment_basic -->
    </fragment>

</LinearLayout>

The layouts of fragment_fragment_1 and fragment_fragment_2 remain the same.

Fragment_1.Java

public class Fragment_1 extends Fragment{

        @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);

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

                    Activity activity = getActivity();

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

            return view;


        }

    }

Fragment_2.Java

public class Fragment_2 extends Fragment{

    View view;

    @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);        
        return view;
    }

    public void setName(String name)
    {
        TextView txtName = (TextView) view.findViewById(R.id.txtViewResult);
        txtName.setText("Hi " + name);
    }

}

Here is the ScreenShot...

This is the classic case of Communication between two Fragments.
But let's cover more basic things first.

Skeleton of the Fragments

FirstFragment

EditText
Button

public class FirstFragment extends Fragment{

      private EditText editext;
      private Button button;

      public static FirstFragment getInstance(){  
           return new FirstFragment();
      }

      public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle bundle){
           View view = inflater.inflate(R.Layout.fragment1,parent,false);
           editext = (EditText)view.findViewById(R.id.editText)
           button = (Button)view.findViewById(R.id.button)
           return view;               

      }

}

SecondFragment

TextView

public class SecondFragment extends Fragment{

      private TextView textView;

      public static SecondFragment getInstance(){  
           return new SecondFragment();
      }

      public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle bundle){
           View view = inflater.inflate(R.Layout.fragment2,parent,false);
           textView = (TextView)view.findViewById(R.id.editText)
           return view;               

      }

      public void showMessage(String msg)
      {
           textView.setText(msg)
      }

}

How to createInstance of Fragments

FirstFragment fragmne1 = FirstFragment.getInstance();
SecondFragment fragmne1 = SecondFragment.getInstance();

How to Add them in the Activity?

getSupportFragmentManager()
         .beginTransaction()
         .add(R.id.placeholder1,fragment1,"TAG1")
         .add(R.id.placeholder2,fragment2,"TAG2")
         .commit();

Now the communication Part

Create an Interface

public interface FragmentListener{
     public void buttonClicked();
}

Implement this interface in the Activity and override the method

public MyActivity extends AppcompatActivity implements MyFragmentListener{

     @Override
     public void buttonClicked(){
          fragment2.showMessage(String msg);
     }

}

Send data from Fragment

1. initialize the listener in the FirstFragment
2. call interface method on Button click.

The final structure of FirstFragment

public class FirstFragment extends Fragment{

      private EditText editext;
      private Button button;
      private MyFragmentListener listener;

      public static FirstFragment getInstance(){  
           return new FirstFragment();
      }

      public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle bundle){
           View view = inflater.inflate(R.Layout.fragment1,parent,false);
           editext = (EditText)view.findViewById(R.id.editText)
           button = (Button)view.findViewById(R.id.button)

           // button click method 
           listener.buttonClicked(editText.getText().toString());

           return view;               

      }

      @Override 
      public void onAttach(Context context){
           listener = (MyFragmentListener)context;
      }

}