It is an open-sourced operating system that is used primarily on mobile
devices, such as cell phones and tablets. It is a Linux kernel-based
system that’s been equipped with rich components that allows developers
to create and run apps that can perform both basic and advanced
functions.
The Google Android SDK is a toolset that developers need in order to
write apps on Android enabled devices. It contains a graphical interface
that emulates an Android driven handheld environment, allowing them to
test and debug their codes.
The Android Framework is an important aspect of the Android
Architecture. Here you can find all the classes and methods that
developers would need in order to write applications on the Android
environment.
AAPT is short for Android Asset Packaging Tool. This tool provides
developers with the ability to deal with zip-compatible archives, which
includes creating, extracting as well as viewing its contents.
6) What is the importance of having an emulator within the Android environment?
The emulator lets
developers “play” around an interface that acts as if it were an actual
mobile device. They can write and test codes, and even debug. Emulators
are a safe place for testing codes especially if it is in the early
design phase.
7) What is the use of an activityCreator?
An activityCreator is the
first step towards the creation of a new Android project. It is made up
of a shell script that will be used to create new file system structure
necessary for writing codes within the Android IDE.
8 ) Describe Activities.
Activities are what you
refer to as the window to a user interface. Just as you create windows
in order to display output or to ask for an input in the form of dialog
boxes, activities play the same role, though it may not always be in the
form of a user interface.
9) What are Intents?
Intents displays
notification messages to the user from within the Android enabled
device. It can be used to alert the user of a particular state that
occurred. Users can be made to respond to intents.
10) Differentiate Activities from Services.
Activities can be closed,
or terminated anytime the user wishes. On the other hand, services are
designed to run behind the scenes, and can act independently. Most
services run continuously, regardless of whether there are certain or no
activities being executed.
11) What items are important in every Android project?
These are the essential items that are present each time an Android project is created:
- AndroidManifest.xml
- build.xml
- bin/
- src/
- res/
- assets/
12) What is the importance of XML-based layouts?
The
use of XML-based layouts provides a consistent and somewhat standard
means of setting GUI definition format. In common practice, layout
details are placed in XML files while other items are placed in source
files.
13) What are containers?
Containers, as
the name itself implies, holds objects and widgets together, depending
on which specific items are needed and in what particular arrangement
that is wanted. Containers may hold labels, fields, buttons, or even
child containers, as examples.
14) What is Orientation?
Orientation,
which can be set using setOrientation(), dictates if the LinearLayout
is represented as a row or as a column. Values are set as either
HORIZONTAL or VERTICAL.
15) What is the importance of Android in the mobile market?
Developers
can write and register apps that will specifically run under the
Android environment. This means that every mobile device that is Android
enabled will be able to support and run these apps. With the growing
popularity of Android mobile devices, developers can take advantage of
this trend by creating and uploading their apps on the Android Market
for distribution to anyone who wants to download it.
16) What do you think are some disadvantages of Android?
Given
that Android is an open-source platform, and the fact that different
Android operating systems have been released on different mobile
devices, there’s no clear cut policy to how applications can adapt with
various OS versions and upgrades. One app that runs on this particular
version of Android OS may or may not run on another version. Another
disadvantage is that since mobile devices such as phones and tabs come
in different sizes and forms, it poses a challenge for developers to
create apps that can adjust correctly to the right screen size and other
varying features and specs.
17) What is adb?
Adb
is short for Android Debug Bridge. It allows developers the power to
execute remote shell commands. Its basic function is to allow and
control communication towards and from the emulator port.
18) What are the four essential states of an activity?
- Active – if the activity is at the foreground
- Paused – if the activity is at the background and still visible
- Stopped – if the activity is not visible and therefore is hidden or obscured by another activity
- Destroyed – when the activity process is killed or completed terminated
19) What is ANR?
ANR
is short for Application Not Responding. This is actually a dialog that
appears to the user whenever an application have been unresponsive for a
long period of time.
20) Which elements can occur only once and must be present?
Among
the different elements, the and elements must be present and can occur
only once. The rest are optional, and can occur as many times as needed.
21) How are escape characters used as attribute?
Escape characters are preceded by double backslashes. For example, a newline character is created using ‘\\n’
22) What is the importance of settings permissions in app development?
Permissions
allow certain restrictions to be imposed primarily to protect data and
code. Without these, codes could be compromised, resulting to defects in
functionality.
23) What is the function of an intent filter?
Because
every component needs to indicate which intents they can respond to,
intent filters are used to filter out intents that these components are
willing to receive. One or more intent filters are possible, depending
on the services and activities that is going to make use of it.
24) Enumerate the three key loops when monitoring an activity?
- Entire lifetime – activity happens between onCreate and onDestroy
- Visible lifetime – activity happens between onStart and onStop
- Foreground lifetime – activity happens between onResume and onPause
25) When is the onStop() method invoked?
A
call to onStop method happens when an activity is no longer visible to
the user, either because another activity has taken over or if in front
of that activity.
26) Is there a case wherein other qualifiers in multiple resources take precedence over locale?
Yes,
there are actually instances wherein some qualifiers can take
precedence over locale. There are two known exceptions, which are the
MCC (mobile country code) and MNC (mobile network code) qualifiers.
27) What are the different states wherein a process is based?
There are 4 possible states:
- foreground activity
- visible activity
- background activity
- empty process
28) How can the ANR be prevented?
One
technique that prevents the Android system from concluding a code that
has been responsive for a long period of time is to create a child
thread. Within the child thread, most of the actual workings of the
codes can be placed, so that the main thread runs with minimal periods
of unresponsive times.
29) What role does Dalvik play in Android development?
Dalvik
serves as a virtual machine, and it is where every Android application
runs. Through Dalvik, a device is able to execute multiple virtual
machines efficiently through better memory management.
30) What is the AndroidManifest.xml?
This
file is essential in every application. It is declared in the root
directory and contains information about the application that the
Android system must know before the codes can be executed.
31) What is the proper way of setting up an Android-powered device for app development?
The following are steps to be followed prior to actual application development in an Android-powered device:
-Declare your application as “debuggable” in your Android Manifest.
-Turn on “USB Debugging” on your device.
-Set up your system to detect your device.
32) Enumerate the steps in creating a bounded service through AIDL.
1. create the .aidl file, which defines the programming interface
2. implement the interface, which involves extending the inner abstract Stub class as well as implanting its methods.
3. expose the interface, which involves implementing the service to the clients.
33) What is the importance of Default Resources?
When
default resources, which contain default strings and files, are not
present, an error will occur and the app will not run. Resources are
placed in specially named subdirectories under the project res/
directory.
34) When dealing with multiple resources, which one takes precedence?
Assuming
that all of these multiple resources are able to match the
configuration of a device, the ‘locale’ qualifier almost always takes
the highest precedence over the others.
35) When does ANR occur?
The
ANR dialog is displayed to the user based on two possible conditions.
One is when there is no response to an input event within 5 seconds, and
the other is when a broadcast receiver is not done executing within 10
seconds.
36) What is AIDL?
AIDL, or Android
Interface Definition Language, handles the interface requirements
between a client and a service so both can communicate at the same level
through interprocess communication or IPC. This process involves
breaking down objects into primitives that Android can understand. This
part is required simply because a process cannot access the memory of
the other process.
37) What data types are supported by AIDL?
AIDL has support for the following data types:
-string
-charSequence
-List
-Map
-all native Java data types like int,long, char and Boolean
38) What is a Fragment?
A
fragment is a part or portion of an activity. It is modular in a sense
that you can move around or combine with other fragments in a single
activity. Fragments are also reusable.
39) What is a visible activity?
A
visible activity is one that sits behind a foreground dialog. It is
actually visible to the user, but not necessarily being in the
foreground itself.
40) When is the best time to kill a foreground activity?
The
foreground activity, being the most important among the other states,
is only killed or terminated as a last resort, especially if it is
already consuming too much memory. When a memory paging state has been
reach by a foreground activity, then it is killed so that the user
interface can retain its responsiveness to the user.
41) Is it possible to use or add a fragment without using a user interface?
Yes,
it is possible to do that, such as when you want to create a background
behavior for a particular activity. You can do this by using
add(Fragment,string) method to add a fragment from the activity.
42) How do you remove icons and widgets from the main screen of the Android device?
To
remove an icon or shortcut, press and hold that icon. You then drag it
downwards to the lower part of the screen where a remove button appears.
43) What are the core components under the Android application architecture?
There are 5 key components under the Android application architecture:
- services
- intent
- resource externalization
- notifications
- content providers
44) What composes a typical Android application project?
A
project under Android development, upon compilation, becomes an .apk
file. This apk file format is actually made up of the
AndroidManifest.xml file, application code, resource files, and other
related files.
45) What is a Sticky Intent?
A
Sticky Intent is a broadcast from sendStickyBroadcast() method such that
the intent floats around even after the broadcast, allowing others to
collect data from it.
46) Do all mobile phones support the latest Android operating system?
Some
Android-powered phone allows you to upgrade to the higher Android
operating system version. However, not all upgrades would allow you to
get the latest version. It depends largely on the capability and specs
of the phone, whether it can support the newer features available under
the latest Android version.
47) What is portable wi-fi hotspot?
Portable
Wi-Fi Hotspot allows you to share your mobile internet connection to
other wireless device. For example, using your Android-powered phone as a
Wi-Fi Hotspot, you can use your laptop to connect to the Internet using
that access point.
48) What is an action?
In
Android development, an action is what the intent sender wants to do or
expected to get as a response. Most application functionality is based
on the intended action.
49) What is the difference between a regular bitmap and a nine-patch image?
In
general, a Nine-patch image allows resizing that can be used as
background or other image size requirements for the target device. The
Nine-patch refers to the way you can resize the image: 4 corners that
are unscaled, 4 edges that are scaled in 1 axis, and the middle one that
can be scaled into both axes.
50) What language is supported by Android for application development?
The
main language supported is Java programming language. Java is the most
popular language for app development, which makes it ideal even for new
Android developers to quickly learn to create and deploy applications in
the Android environment.