Iat 381 Quiz 2

Front 1

Button & Button click event

Back 1

- after the button is clicked

- Android system receive the event

- only the listener is interested in reacting to the event * OnClickListener

Front 2

a. Tell Android system that we are interested in listening to button clicks

Back 2

public class MainAcitivity extends Activity implements View.OnClickListener

Front 3

b. retrieve/linking the button from the XML layout into Java code

(protected void onCreate(Bundle savedInstanceState))

Back 3

myButton = (Button) findViewById(R.id.button);

Front 4

c. tell Java that we are listening to the button being clicked

(protected void onCreate(Bundle savedInstanceState))

Back 4

myButton.setOnClickListener(this);

Front 5

d. behavior: what should happen when the button is clicked

Back 5

@Override

public void onClick(View v) {

Toast.makeText(this, "button clicked", Toast.LENGTH_LONG).show()

Front 6

view

Back 6

an object that occupies a rectangular area on screen and is responsible for handling events

eg: button

Front 7

view group

Back 7

occupies a rectangular area on screen, is invisible and holds other views in a certain structure (grid, horizontally, vertically, table etc)

Front 8

Linear Layout in XML

Back 8

all views and ViewGroups are placed in 1 ViewGroup which is the root

Front 9

root view

Back 9

width & height usuallt set to match_parent, to fill up all available space

Front 10

layout_weight attribute

Back 10

- affect the size of 1 view in relationship to other views

- default 0

- layout_width is redundant

- layout_width should be "0dp"

Front 11

layout_gravity attribute

Back 11

controls the placement of the view in the layout inside the parent

* outside of view, ref to parent

Front 12

gravity attribute

Back 12

controls where the contents of the view should appear inside the view

* inside of view, content

Front 13

calculator example

Back 13

vertical layout { //@+id/biglayout

horizontal layout {} //@+id/horizTopLayout

table layout {} //@+id/keysTableLayout

}

Front 14

ListView concept

Back 14

1. define the data source

2. define the ListAdapter : class to manage the date

3. define the user interaction (ListView) : class to manage the apperance

Front 15

Adapter

Back 15

- responsible for managing the data

- access the data display it in a view

* takes data and convert it

Front 16

types of Adapter

Back 16

1. array adapter

2. cursor adapter

3. base adapter

Front 17

1. define the data source

Back 17

String [] courses = {"381"," 445"," 455"};

Front 18

2. define the ListAdapter

Back 18

ArrayAdapter <String> adapter = new ArrayAdapter <String> (this, android.R.layout.simple_List_item_1, courses);

this --> content

android.R.layout.simple_List_item_1 --> TextView

courses --> data source

Front 19

3. define the user interface

Back 19

a. MainActivity --> implements interface OnItemClickListener

b. onCreate --> myList.setOnItemClickListener (this);

c. implements the method of the OnItemClickListener interface -->

@Override

public void onItemClick (AdapterView<?> parent, View view, int position, long id) {}

Front 20

what is intent?

Back 20

asynchronous messaging mechanism

that allow the Android components to request functionality from other components of the Android system (eg: Activity,Service, Broadcast receiver),

and it can also be used to signal the Android system that a certain event has occured

Front 21

explicit intent

Back 21

define the component name which should be called by the Android system by using Java class as identifier

Intent i = new Intent (this, ActivityTwo.class)

Front 22

implicit intent

Back 22

define the action which should be performed

Intent i = (Intent.ACTION_VIEW);

the Android system searches for all components which are registered for the specific action and the data type

* if only 1 components is found, it start directly

*many found: get a selection dialog and decide which component to use