Mobile Computing

Question 1

If app does not respond in a few seconds an Application Not Responding (ANR) Dialog runs:

Accepted Answer

To keep app responsive long running tasks should NOT RUN on MAIN (UI) THREAD

Accepted Answer

Networking should NOT be done on UI thread

Accepted Answer

UI thread has queue of messages. Messages pop to front for UI to process

Accepted Answer

if thread is handling a request/message. It can't handle others (taps/clicks)

Question 2

What are the two main android threading rules?

Accepted Answer

All UI updating should be done on the UI thread.

Accepted Answer

trying to access UI from a that other than UI gives CalledFromWrongThreadException

Question 3

Built-in tools that allow us to launch long-running tasks in the background: intent services, async task (shorter)

Answer

true

Question 4

AsyncTask

Accepted Answer

Abstract Helper Class

Accepted Answer

Performs task asynchronously

Accepted Answer

Can synchronize with the UI thread for updates and task completion

Accepted Answer

handles thread creation, management and synchronization

Accepted Answer

do not survive activity restarts (orientation)

Question 5

use Java does not support primitive types in Generics, wrapper classes must be used

Answer

true

Question 6

Room:

Accepted Answer

Less boiler plate code and handles the tedious OpenHelpe rand create table statement

Accepted Answer

compile time verification of SQL queries as opposed to runtime exceptions

Accepted Answer

e background processing for all db-access

Accepted Answer

use of annotations

Question 7

Which of the following is not a major (3x) component of room?

Accepted Answer

DaoDatabase

Answer

RoomDatabase (room abstraction over SQLite DB

Answer

Entity: mark POJO to give room what it needs to create the table

Answer

Dao: data access object to access database, generated at compile time.

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