4.1 Fill in the blanks in each of the following statements:
a) ___________are typically used to launch activities—they indicate an action to be performed and the data on which that action is to be performed.
b) We implement interface ___________ to handle the events that occur when the user touches a button on an AlertDialog
.
c) Lengthy data access should never be done in the UI thread; otherwise, the app will display a(n) ___________ dialog—typically after five seconds of inactivity.
d) An Intent
is a description of an action to be performed with associated ___________.
e) ___________Intents
specify an exact Activity
class to run in the same app.
f) When you create the project for each Android app in Eclipse, the ADT Plugin creates and configures the ___________ file (also known as the app’s manifest), which describes information about the app.
g) A(n) ___________ displays a list items that is scrollable if the complete list cannot be displayed on the screen.
h) A(n) ___________ creates an object that populates the ListView
using data from an ArrayList
collection object.
i) ___________ is a subclass of ImageView
which provides additional capabilities that enable an image to be used like a Button
object.
4.2 State whether each of the following is true or false. If false, explain why.
a) Extensive input/output should be performed on the UI thread; otherwise, this will affect your app’s responsiveness.
b) You call toArray
(with an empty String
array as an argument) on the Set
object to convert the Set
into an array of String
s.
c) When an Activity
’s primary task is to display a scrollable list of items, you can extend class ListActivity
, which uses a ListView
that occupies the entire app as its default layout.
d) ListView
is a subclass of Adapter
—a GUI component is bound to a data source.
e) When customizing a ListActivity
subclass’s GUI, the layout must contain a ListView
with its Id attribute set to "@android:id/list"
—the name that class ListActivity
uses to reference its ListView
.