This document covers Android programming, focusing on using selection widgets and adapters. It introduces concepts such as ArrayAdapter and its applications in ListView, GridView, and Spinners, along with example projects for practical implementation. The document serves as a lesson on how to bind data to UI elements through adapters in Android development.

1. Android Programming
Lesson 3
Using Selection Widgets
NGUYEN The Linh

2. Android Programming
Contents
1 Introducing Adapters
2 Using Selection Widgets
3 Exercise 3
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3. Android Programming
Using Selection Widgets
Introducing Adapters
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4. Android Programming
Introducing Adapters
 Adapters are bridging classes that bind data to user-
interface Views.
 Using ArrayAdapter
 The ArrayAdapter is a generic class that binds AdapterViews to an array of
objects.
 By default, the ArrayAdapter binds the toString() value of each object to a
TextView control defined within a layout.
 To apply an Adapter to an AdapterView-derived class, you call the View’s
setAdapter() method, passing in an Adapter instance, as shown in the snippet
below:
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5. Android Programming
Introducing Adapters
 Using ArrayAdapter (cont.)
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6. Android Programming
Introducing Adapters
 Example 3.1
 Using Basic ArrayAdapter
 Example 3.1 project
• MainActivity.java
• activity_main.xml
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7. Android Programming
Introducing Adapters
 Custom ArrayAdapter
 You can subclass ArrayAdapter and override getView() to “roll
your own” views:
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8. Android Programming
Using Selection Widgets
Using Selection Widgets
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9. Android Programming
Using Selection Widgets
 ListView
 The classic Android ListView is a plain list of text.
 However, you can have a list whose rows are made up of icons,
or icons and text, or check-boxes and text, or whatever you
want.
 Update Example 3.1 project
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10. Android Programming
Using Selection Widgets
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11. Android Programming
Using Selection Widgets
 ListView (cont.)
 Custom ArrayAdapter for binding more data
 See Example 3.2
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12. Android Programming
Using Selection Widgets
 Example 3.2
 Custom ArrayAdapter
 Example 3.2 project
• MainActivity.java
• Person.java
• MyArrayAdapter.java
• activity_main.xml
• list_item.xml
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13. Android Programming
Using Selection Widgets
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14. Android Programming
Using Selection Widgets
Better.
Stronger.
Faster.
Using
convert
View
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15. Android Programming
Using Selection Widgets
 GridView
 As the name suggests, GridView gives you a two-dimensional
grid of items to choose from.
 You have moderate control over the number and size of the
columns; the number of rows is dynamically determined based
on the number of items the supplied adapter says are available
for viewing.
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16. Android Programming
Using Selection Widgets
 GridView (cont.)
 Properties
• android:numColumns spells out how many columns there are, or, if you
supply a value of auto_fit, Android will compute the number of columns
based on available space and the following properties.
• android:verticalSpacing and its counterpart android:horizontalSpacing
indicate how much whitespace there should be between items in the grid.
• android:columnWidth indicates how many pixels wide each column should
be.
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17. Android Programming
Using Selection Widgets
 GridView (cont.)
 Properties (cont.)
• android:stretchMode; this should be columnWidth to have the columns
take up available space or spacingWidth to have the whitespace between
columns absorb extra space.
 Otherwise, the GridView works much like any other selection
widget—use setAdapter() to provide the data and child views.
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18. Android Programming
Using Selection Widgets
 Example 3.3
 GridView
 Example 3.3 project
• MainActivity.java
• MyArrayAdapter.java
• activity_main.xml
• gridview_item.xml
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19. Android Programming
Using Selection Widgets
 Spinners
 Spinners provide a quick way to select one value from a set.
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20. Android Programming
Using Selection Widgets
 Spinners (cont.)
 The choices you provide for the spinner can come from any
source, but must be provided through an SpinnerAdapter, such
as an ArrayAdapter
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21. Android Programming
Exercise 3
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22. Android Programming