In the below example I have created Expanding toolbar in android. Here first I have created CoordinatorLayout in activity_main.xml layout then I have added RecyclerView, CollapsingToolbarLayout and Toolbar with in CoordinatorLayout, In MainActivity I have intialize Toolbar and CollapsingToolbarLayout, And In this Expanding Toolbar example i have also used RecyclerView function and RecyclerView support library. You can see below program it clearly describe you How to make Expanding Toolbar.

Step(1)Added first RecyclerView  support  library -
 

   compile 'com.android.support:recyclerview-v7:22.2.1'

Srep(2)activity_main.xml layout-
 

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycler"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="180dp"
        android:theme="@style/ThemeOverlay.AppCompat.Dark">

        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/collapse_toolbar"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:layout_collapseMode="pin" />
        </android.support.design.widget.CollapsingToolbarLayout>
    </android.support.design.widget.AppBarLayout>

</android.support.design.widget.CoordinatorLayout>

Step(3)MainActivity-
 

 public class MainActivity extends AppCompatActivity {
    
        private ArrayList<String> stringArrayList;
        private RecyclerView recyclerView;

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

            Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
            setSupportActionBar(toolbar);
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);

            CollapsingToolbarLayout collapsingToolbar = (CollapsingToolbarLayout) findViewById(R.id.collapse_toolbar);
            collapsingToolbar.setTitle(getString(R.string.expand));

            recyclerView = (RecyclerView) findViewById(R.id.recycler);
            recyclerView.setHasFixedSize(true);
            LinearLayoutManager layoutManager = new LinearLayoutManager(this);
            recyclerView.setLayoutManager(layoutManager);

            setData(); //adding data to array list

        }

        private void setData() {
            stringArrayList = new ArrayList<>();

            for (int i = 0; i < 100; i++) {
                stringArrayList.add("Item " + (i + 1));
            }
        }
    }