Android Application Development Cookbook: 93 Recipes for Building Winning Apps

 
Recipe 2.4 using checkBoxes
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49
Figure 2-6 
reCiPe 2.4 
using CheCKboxes
Android Versions
Level 1 and above
permissions
None
source code to download from Wrox.com
CheckBoxes.zip
Like radio buttons, checkboxes enable users to select one or more options from a list. A 
CheckBox
has two states: checked or unchecked. Unlike radio buttons, checkboxes can be checked and 
unchecked by the user without regard to the state of other checkboxes. This recipe shows how to use 
checkboxes in your Android application. 
www.it-ebooks.info

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50
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ChAPter 2
using Views to design the user interFAce
solution
Assume you have the following code snippet in the 
activity_main.xml
file: 
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
android:id="@+id/chkAutosave"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Autosave" />
android:id="@+id/star"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

The 
CheckBox
element defines an item for users to check or uncheck. Android supports a special 
type of checkbox known as the star checkbox. You display a star checkbox by setting the 
style
attribute and setting its value to 
?android:attr/starStyle
.
Figure 2-7 shows the default checkbox and the star checkbox. The top part shows the unchecked 
state of the two checkboxes, and the lower portion shows the checked state.
The following code snippet shows how to determine whether a checkbox is 
checked:
package net.learn2develop.checkboxes;
import android.app.Activity;
import android.os.Bundle;