Chapter 3

Question 1

Activity method notifies the activity of the change in its state during a transition (true/false)

Answer 1

true

Question 2

why override onCreate(…)?

Answer 2

inflating widgets and putting them on screen(setContentView(int)). getting references to inflated widgets. setting listeners to widgets. connecting to external model data.

Question 3

android.util.log

Answer 3

sends log messages to a shared system-level log.

Question 4

public static in d(String tag, String msg)

Answer 4

d stands for debug and refers to the level of the log message.tag identifies the source of the message, and msg is the contents of the message.

Question 5

why call the superclass implementations before you log your messages?

Answer 5

superclass calls are required and is critical in onCreate(…)

Question 6

what is @Override used for?

Answer 6

asks the compiler to ensure that the class actually has the method that you are attempting to override.

Question 7

rotating a device changes the device configuration (t/f)

Answer 7

true

Question 8

device configuration

Answer 8

set of characteristics that describe the current state of an individual device.

Question 9

characteristics that make up device configuration:

Answer 9

screen orientation, screen density, screen size, keyboard type, dock mode, language, and more

Question 10

screen density is a fixed component of the device configuration and cannot change at runtime (t/f)

Answer 10

true

Question 11

alternative resource

Answer 11

resource that better match a new configuration

Question 12

configuration qualifier

Answer 12

configuration qualifier on res sub directories are how android identifies which resources best match the current device configuration.

Question 13

FrameLayout

Answer 13

FrameLayout simplest viewgroup and does not arrange its children in any particular manner. child views arrange according to their android:layout_gravity attributs

Question 14

protected void onSaveInstanceState(Bundle outState)

Answer 14

normally called by the system before onPause(), onStop(), and onDestroy(). default implementation asks all of the activities views to save their state as data in the Bundle object. data is saved to the bundle object and is then stuffed into your activity’s activity record by the OS.

Question 15

Bundle

Answer 15

structure that maps string keys to values of certain limited types.

Question 16

super.onCreate(Bundle)

Answer 16

in the superclass implementation, the saved state of the views is retrieved and used to recreate the activity’s view hierarchy.

Question 17

types that you can save to and restore from a Bundle are primitive types and objects that implement the Serializable interface (t/f)

Answer 17

true.when you are creating custom classes, be sure to implement Serializable if you want to save them in onsaveInstanceState(…)

Question 18

android will destroy a running activity to reclaim memory(t/f)

Answer 18

false. the activity mus be in the paused or stopped state to be destroyed.

Question 19

activity record

Answer 19

activity record object lives in the OS. the OS can reanimate the activity using the activity record when it needs to.

Question 20

how is activity record discarded?

Answer 20

when the user presses the Back button. discarded on reboot and may also be discarded if they are no used for a long time.