Android Basics Ch 1

Front 1

activity

Back 1

instance of Activity, a class in Android SDK responsible for managing user interaction with a screen of information

Front 2

In Android, what is a layout made up of?

Back 2

Definitions written in XML, where each definition is used to create an object that appears on the screen

Front 3

"reverse DNS" convention

Back 3

domain name of organization is reversed and suffixed with identifiers --> keeps package name unique

Front 4

Is it better to create a subclass of Activity called Quiz or QuizActivity?

Back 4

QuizActivity

Front 5

What is the recommended formatting for the name of the layout?

Back 5

reverses order of activity name, all lowercase, underscore between words

ActivityQuiz --> quiz_activity

Front 6

widget (in relation to Android)

Back 6

building blocks we'll use to compose user interface. can show text, graphics, interact with user, arrange other widgets.

e.g.: buttons, text input, checkboxes

Front 7

Every widget is an instance of what class (or one of its subclasses)?

Back 7

View

Front 8

Is layout XML validated?

Back 8

No! Be careful of typos

Front 9

ViewGroup: What is it? Give an example

Back 9

ViewGroup: widget that contains and arranges other widgets

Examples: LinearLayout, FrameLayout, RelativeLayout, TableLayout

Front 10

Set the width of a widget to make the view as big as the parent

Back 10

android:layout_width="match_parent"

Front 11

Set the height of a widget to make the view as big as the contents require

Back 11

android:layout_height="wrap_content"

Front 12

Add padding

Back 12

android:padding="24dp"

Front 13

create a vertical linear layout. create a horizontal linear layout

Back 13

< LinearLayout android:orientation="horizontal" >

< LinearLayout android:orientation="vertical" >

Front 14

String resource

Back 14

string that lives in a strings file (separate xml file). You can hard-code literal strings into your layout xml file, but it's a bad idea. use string resources instead

Front 15

specify the text in a TextView using a string resource

Back 15

< TextView android:text="@string/question_text" />

Front 16

specify the text for the false button in the strings.xml file

Back 16

< string name="false_button" > False string >

Front 17

Can you have multiple string files in a project?

Back 17

Yes, as long as the file is located in res/values/, has a < resources > root element, and contains child string elements

Front 18

What method is called in the .java file when an instance of the activity subclass is created?

Back 18

onCreate(bundle)

Front 19

What does it mean to inflate a layout? What method inflates a layout and puts it on the screen?

Back 19

Inflate a layout: each widget in the layout file is instantiated as defined by its attributes

Method: public void setContentView(int layoutResID) --> this method is part of the Activity class

Front 20

resource

Back 20

piece of the application that is not code: xml files, string files, audio/image files, etc.

Front 21

resource id for layout for the QuizActivity subclass

Back 21

R.layout.activity_quiz

Front 22

Does every widget need a resource ID? How do you generate a resource ID for a true button/widget?

Back 22

No, not every widget needs a resource ID

To generate, include the android:id attribute in the widget's definition

e.g.

< Button android:id="@+id/true_button"

Front 23

Android naming convention for instance (member) variable names

Back 23

mMyVariable

(prepend with m for member variable)

Front 24

Organizing imports:

shortcut for Mac in Eclipse

shortcut for PC in Eclipse

Back 24

Mac: Cmd+Shift+O

PC: Ctrl+Shift+O

Front 25

Three steps to declaring and wiring up widgets

Back 25

1. Add member variables

2. Get references to the inflated View objects

3. Set listeners on those objects to respond to user actions

Front 26

Add a member variable for a true button

Back 26

private Button mTrueButton;

Front 27

Activity method to get a reference to an inflated widget

Get the reference to the inflated View object for mTrueButton

Back 27

publiv View getViewById(int id)

mTrueButton = (Button)getViewById(R.id.true_button);

Front 28

Set a listener to inform you when the true button has been pressed

Back 28

mTrueButton.setOnClickListener(

new View.OnClickListener(){

@Override

public void OnClick(){

//insert code

}});

implements the OnClickListener Interface

Front 29

This book uses anonymous inner classes for listeners. What's a trick for remembering the syntax?

Back 29

Everything within the outermost set of parentheses is passed into .setOnClickListener(OnClickListener)

Front 30

toast

Back 30

short message that informs the user of something but does not require any input or action (e.g., a toast providing feedback about whether they got the answer right or wrong)

Front 31

method to create a toast

Back 31

public static Toast makeText(Context context, int resId, int duration);

Front 32

What is the context parameter when making a toast?

Back 32

typically an instance of Activity

Front 33

Once you've created a toast, how do you show it on the screen?

Back 33

Toast.show();

Front 34

make and show a toast to display an incorrect message in QuizActivity

Back 34

mTrueButton.setOnClickListener(

new View.OnClickListener(){

@Override

public void onClick(View v){

Toast.makeText(QuizActivity.this, R.string.incorrect_toast, Toast.LENGTH_SHORT).show();

}});

Front 35

AVD

Back 35

Android Virtual Device

useful, but a hardware device gives more accurate results

Front 36

Does Eclipse build projects on command?

Back 36

No, it builds projects as you modify them

Front 37

What are two popular tools for building Android apps besides Eclipse?

Back 37

Maven and ant