Android - Inflate (a layout XML to a view UI object)

setContentView

• setContentView method of an activity.

@Override
protected void onCreate(Bundle savedInstanceState) {

	// Parent call (All state function must have it)
	super.onCreate(savedInstanceState);

	// The XML layout located in res>layout>activity_main.xml
       // will be inflated.
	setContentView(R.layout.activity_main);

}

The loading must occur:

• in the Activity.onCreate() callback implementation (called by the Android framework when the Activity is launched. See Android - (Activity|Fragment) Lifecycle)
• by calling setContentView() and passing as parameter the XML layout resource location in the form of: R.layout.layout_file_name.

For example, if your XML layout is saved as main_layout.xml, you would load it for your Activity like so:

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main_layout);
}

LayoutInflater

LayoutInflater inflater = LayoutInflater.from(YourActivity.this); // or (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View viewMyLayout = inflater.inflate(R.layout.my_layout, null);

Inflate (One Pane)

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
						 Bundle savedInstanceState) {

	View rootView = inflater.inflate(R.layout.fragment_main, container, false);
	return rootView;

}

The inflate method inflates the View hierarchy and binds to it all it one step.

Multi- Screen (Two-pane)

• The layout file activity_main.xml:

<!--
    This layout is a two-pane layout for the Items master/detail flow.
    -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:baselineAligned="false"
    android:divider="?android:attr/dividerHorizontal"
    android:orientation="horizontal"
    tools:context="com.example.android.myapp.MainActivity">
    
    <!-- Static Fragment that references the main fragment class statically in the android:name attribute-->
    <fragment
        android:id="@+id/fragment_main"
        android:name="com.example.android.myapp.myMainFragment"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="2"
        tools:layout="@android:layout/list_content" />
   
    <!-- Dynamic detail Fragment that will be instantiated at runtime in the activity -->
    <FrameLayout
        android:id="@+id/fragment_detail_container"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="4" />

</LinearLayout>

• The code: From MainActivity.java

@Override
protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	
	setContentView(R.layout.activity_main);
	if (findViewById(R.id.fragment_detail_container) != null) {

		// The detail container view will be present only in the large-screen layouts
		// (res/layout-sw600dp). If this view is present, then the activity should be
		// in two-pane mode.

		// Replacing the container dynamically using a fragment transaction.
                // Check if savedInstance is null because
                // If we rotate the phone, the system saves the fragment state in the saved state bundle (savedInstanceState) 
                // and is smart enough to restore this state. 
		if (savedInstanceState == null) {
			getSupportFragmentManager().beginTransaction()
					.replace(R.id.weather_detail_container, new DetailFragment(), "DETAILFRAGMENT_TAG")
					.commit();
		}
	} 

	// Set  an Adapter or other onCreate activity
	// *** SunshineSyncAdapter.initializeSyncAdapter(this);
	
}