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#3: Collapsing Toolbar

Collapsing Toolbar         CollapsingToolbarLayout is a ViewGroup that provides many of the visual characteristics and interactions for collapsing toolbars specified in the material guidelines. To create the collapsing toolbar, CollapsingToolbarLayout integrates with AppBarLayout, CoordinatorLayout, Toolbar, and a scrollable content view, such as RecyclerView. How to work with Collapsing Toolbar:     To add a collapsing toolbar to your layout, place the CollapsingToolbarLayout inside an AppBarLayout. Then, add a Toolbar and any other views as a child to the CollapsingToolbarLayout. Make sure that the entire view structure is inside a CoordinatorLayout to take advantage of CollapsingToolbarLayout’s scrolling and features. Sample Code: <android.support.design.widget.CoordinatorLayout     android:layout_width="match_parent"     android:layout_height="match_parent">     <!-- Scrollable view here -->   <com.google.android.mat

#2: SQLite database

SQLite What is SQLite? SQLite is an Open Source Database which is embedded into Android. SQLite supports standard relational database features like SQL syntax, transactions and prepared statements. In addition it requires only little memory at runtime (approx. 250 KByte). SQLite supports the data types   TEXT   (similar to String in Java),   INTEGER   (similar to long in Java) and REAL   (similar to double in Java). All other types must be converted into one of these fields before saving them in the database. SQLite itself does not validate if the types written to the columns are actually of the defined type, e.g. you can write an integer into a string column and vice versa. SQLite in Android? SQLite is available on every Android device. Using an SQLite database in Android does not require any database setup or administration. You only have to define the SQL statements for creating and updating the database. Afterwards the database is automatically managed fo

#1: Layouts in Android

Layouts A layout defines the structure for a user interface in your app, such as in an  activity . All elements in the layout are built using a hierarchy of  View  and  ViewGroup  objects. A  View  usually draws something the user can see and interact with. Whereas a  ViewGroup  is an invisible container that defines the layout structure for  View  and other ViewGroup  objects, as shown in figure 1. Figure 1.  Illustration of a view hierarchy, which defines a UI layout The  View  objects are usually called "widgets" and can be one of many subclasses, such as  Button  or  TextView . The  ViewGroup  objects are usually called "layouts" can be one of many types that provide a different layout structure, such as  LinearLayout  or  ConstraintLayout   . You can declare a layout in two ways: Declare UI elements in XML . Android provides a straightforward XML vocabulary that corresponds to the View classes and subclasses, such as those for widgets and l