AndroidFragment.doc

      Fragments
      A Fragment is a piece of an activity which enable more modular activity design. It will not be wrong if we say, a fragment is a kind of sub-activity.
      •	A fragment has its own layout and its own behaviour with its own life cycle callbacks.
      •	You can add or remove fragments in an activity while the activity is running.
      •	You can combine multiple fragments in a single activity to build a multi-plane UI.
      •	A fragment can be used in multiple activities.
      •	Fragment life cycle is closely related to the life cycle of its host activity which means when the activity is paused, all the fragments available in the activity will also be stopped.
      •	A fragment can implement a behaviour that has no user interface component.
      •	Fragments were added to the Android API in Honeycomb version of Android which API version 11.
      
      
      Steps
        1.	Add fragment classes and create their layouts
        public class first extends Fragment {

           public first() {
                // Required empty public constructor
            }


            @Override
            public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                     Bundle savedInstanceState) {
                // Inflate the layout for this fragment
                return inflater.inflate(R.layout.fragment_first, container, false);
            }

        }
        Here fragment_first is the layout
        
        
        
        
          2.	Write following code to use fragment in activity
          first f1=new first(); //User defined fragment class
          FragmentTransaction ft=getSupportFragmentManager().beginTransaction();
          ft.replace(R.id.fragment_container,f1);
          ft.addToBackStack(null);
          ft.commit();
          
          

          Full Code


          activity_main.xml
          <?xml version="1.0" encoding="utf-8"?>
          <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
              xmlns:app="http://schemas.android.com/apk/res-auto"
              xmlns:tools="http://schemas.android.com/tools"
              android:id="@+id/content_main"
              android:layout_width="match_parent"
              android:layout_height="match_parent"

              app:layout_behavior="@string/appbar_scrolling_view_behavior"
              tools:context="com.example.vgt.myapplication.MainActivity"
              tools:showIn="@layout/activity_main" android:background="#abcdef">

              <LinearLayout
                  android:orientation="vertical"
                  android:layout_width="match_parent"
                  android:layout_height="match_parent"
                  android:layout_alignParentTop="true"
                  android:layout_marginTop="17dp"
                  android:layout_alignParentRight="true"
                  android:layout_alignParentEnd="true">

                  <LinearLayout
                      android:orientation="horizontal"
                      android:layout_width="match_parent"
                      android:layout_height="wrap_content">


                      <Button
                          android:text="First"
                          android:layout_width="wrap_content"
                          android:layout_height="wrap_content"
                          android:id="@+id/button"
                          android:layout_weight="1" />

                      <Button
                          android:text="Second"
                          android:layout_width="wrap_content"
                          android:layout_height="wrap_content"
                          android:id="@+id/button1"
                          android:layout_weight="1" />
                  </LinearLayout>
                  <FrameLayout
                      android:layout_width="match_parent"
                      android:layout_height="400dp"
                      android:id="@+id/fragment_container" android:background="#d5d5ff"
                      >

                  </FrameLayout>
              </LinearLayout>
          </RelativeLayout>

        fragment_first.xml
        <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:tools="http://schemas.android.com/tools"
            android:layout_width="match_parent"
            android:layout_height="400dp"
            tools:context="com.example.vgt.myapplication.first" android:background="#999999">


            <LinearLayout
                android:orientation="vertical"
                android:layout_width="match_parent"
                android:layout_height="match_parent">

                <TextView
                    android:text="TextView"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/textView" />

                <Button
                    android:text="Button"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/button3" />
            </LinearLayout>
        </FrameLayout>

        fragment_second.xml
        <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:tools="http://schemas.android.com/tools"
            android:layout_width="match_parent"
            android:layout_height="400dp"
            tools:context="com.example.vgt.myapplication.second" android:background="#ffd5d5">


            <LinearLayout
                android:orientation="vertical"
                android:layout_width="match_parent"
                android:layout_height="match_parent">

                <Button
                    android:text="Button"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/button4" />

                <Button
                    android:text="Button"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/button5" />
            </LinearLayout>
        </FrameLayout>

        MainActivity.java
        public class MainActivity extends FragmentActivity {

            Button b1,b2;
            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_main);



                b1= (Button) findViewById(R.id.button);
                b2=(Button) findViewById(R.id.button1);

                b1.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
            //create a object of fragment class
                        first f1=new first();

                        FragmentTransaction ft = getSupportFragmentManager(). beginTransaction();
                        ft.replace(R.id.fragment_container,f1);
                        ft.addToBackStack(null);
                        ft.commit();
                    }
                });

                b2.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {

                        second f2=new second();
                        FragmentTransaction ft = getSupportFragmentManager(). beginTransaction();
                        ft.replace(R.id.fragment_container,f2);
                        ft.addToBackStack(null);
                        ft.commit();
                    }
                });
            }
        }

        First.java
        public class first extends Fragment {


            public second() {
                // Required empty public constructor
            }


            @Override
            public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                     Bundle savedInstanceState) {
                // Inflate the layout for this fragment
                return inflater.inflate(R.layout.fragment_first, container, false);
            }

        }

        Second.java
        public class second extends Fragment {


            public second() {
                // Required empty public constructor
            }


            @Override
            public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                     Bundle savedInstanceState) {
                // Inflate the layout for this fragment
                return inflater.inflate(R.layout.fragment_second, container, false);
            }

        }

        To access the components of UI of fragment, override following method in fragment class.
        @Override
        public void onViewCreated(View view, @Nullable final Bundle savedInstanceState) {
            super.onViewCreated(view, savedInstanceState);

            b1=(Button) view.findViewById(R.id.button3);
            b1.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Toast.makeText(getActivity(),"Hello",Toast.LENGTH_LONG).show();
                }
            });
        }