Refreshing - Android fragments

Fragments are ways by which you can create multiple views in a single Activity, to avoiding to create multiple activities. You can add / remove fragments while the activity is running. 

You can create a fragment in 2 ways: - static using XML and dynamic using programmatically

XML: 

• Create 2 fragment classes using the wizard. This will create a class that extends Fragment and create the layout xml accordingly. 
• headerFragment
• ArticleFragment. 
• Now add the 2 fragments in the main activity XML file as below. 

<fragment

    android:layout_width="match_parent"

    android:layout_height="0dp"

    android:id="@+id/headline_fragment"

    android:layout_weight="1"

    android:name="io.ctrlspace.fragmentexample.HeadlineFragment"> </fragment>

 <fragment

     android:layout_width="match_parent"

     android:layout_height="0dp"

     android:id="@+id/article_fragment"

     android:layout_weight="1"

     android:name="io.ctrlspace.fragmentexample.ArticleFragment"> </fragment>

Now this is not of much use since we add these in static xml, often we may need to add dynamically fragments based on runtime logic. 

Programmatically: 

• Create a simple Empty Activity - say MainActivity. 
• In the main Activity layout file, add a layout to hold the fragments, say a frame layout 
• Now create a Fragment using Android studio - call it as HomeFragment. This will create a Java class that extends Fragment and a fragment layout file. 
• Add some content for the fragment in the layout design to identify that its a fragment content, say add a text box with a text inside first fragment. 
• In the main Activity add the following code. 
• Get the FragmentManager instance
• Start the transaction of the fragment manager.
• Add or replace the fragment using the add / replace method in the fragment transaction, pass the fragment container and the fragment to be added or replaced to this method. 
• Commit the transaction. 

public static FragmentManager fragmentManager;

@Override

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);

    fragmentManager = getSupportFragmentManager();

    if(findViewById(R.id.fragment_container) != null) {

        if (savedInstanceState != null) {

            return;

        }

        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

        HomeFragment homeFragment = new HomeFragment();

        fragmentTransaction.add(R.id.fragment_container, homeFragment, null);

        fragmentTransaction.commit();

    }

}

Fragment to Activity communication is handled in a different way - you can view the source code for this here.