Lecture Slides for Preferences and Menus [Android ]

Preferences & Menus

Software Development for Portable Devices BITS Pilani Goa Campus

Sem I 2011-12

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Foundation of :

Saving Simple Application Data

• Shared Preferences• Saved Application State• Files

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Shared Preferences

• Used to store UI state, user preferences, or application settings

• Shared Preferences let you save groups of key/value pairs of primitive data as named preferences.

• They are most commonly used to persist data across user sessions and to share settings among application components.

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Creating And Saving Preferences

• getSharedPreferences(Pref_File_Name,Mode)• Creating new Shared Preferences->Code• Retreiving saved Shared Preferences->Code• Its that Simple• getDefaultSharedPreferences(this)->Gets a

SharedPreferences instance that points to the default file that is used by the preference framework in the given context.

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Preferences Activity Framework

• Android offers an XML-driven framework • Native preference screens.• Having a native feel to your app is important• The Preference Activity framework consists of

three parts:– Preference Screen Layout– Preference Activity– Shared Preference Change Listener

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Preference Screen Layout

• Stored in the res/xml resources folder. – See folder structure

• Each preference layout is defined as a hierarchy, beginning with a single PreferenceScreen element.

• The PreferenceCategory is a category with preferences.

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The Specific Attributes

• android:key• android:title• android:summary• android:defaultValue

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Native Preference Controls

• ListPreference : The preference equivalent of a spinner.

• EditTextPreference : Allows users to enter a string value as a preference.

• CheckBoxPreference :A standard preference checkbox control. Used to set preferences to true or false.

• RingtonePreference : A specialized List Preference that presents the list of available ringtones for user selection.

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Import System Preference Screens

• Invoke any Activity within your Preference Screen using an Intent.

• See Code• The android.provider.Settings class includes a

number of android.settings.* constants that can be used to invoke the system settings screens.

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Preference Activity

• extend the PreferenceActivity class• Call addPreferencesFromResource to inflate

the preferences

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Menus

• Types– Options Menu– Context Menu– Submenu

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Creating a Menu Resource

• Define a menu and all its items in an XML.• Inflate the menu• Location of your menu resource res/menu/

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Inflating a Menu Resource

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Options Menu

• The Menu that’s pops up when you press the menu button

• If there are more than six items in the Options Menu, Android Places the “More” Icon.

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Responding to user action

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Context Menu

• On Android, a context menu is displayed when the user performs a "long press" (press and hold) on an item.

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Context Menu

• In order for a View to provide a context menu, you must "register" the view for a context menu. Call registerForContextMenu(View view)

• View that the user selected • ContextMenu.ContextMenuInfo object that

provides additional information about the item selected.

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• Same as before

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Responding to user action

Attention!

• Join • Course Name CS – IS C314• Official Medium for all the question and

answers• Very Useful while collaborating for projects

and preparing for labs

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References

• Menu Tutorial - http://developer.android.com/guide/topics/ui/menus.html

• Shared Preferenceshttp://developer.android.com/reference/

android/content/SharedPreferences.html

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Thank You

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