Pro Android with Kotlin

186
CHAPTER 8: APIs
LIST -> {
findPreference(key).summary =
(findPreference(key) as ListPreference).
entry
}
RINGTONE -> {
val uriStr = getString(key, "") ?: ""
findPreference(key).summary =
getRingtoneName(Uri.parse(uriStr))
}
}
}
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
// Load the preferences from an XML resource
addPreferencesFromResource(R.xml.preferences)
val sharedPref = PreferenceManager.
getDefaultSharedPreferences(activity)
sharedPref.registerOnSharedPreferenceChangeListener(
this)
with(sharedPref) {
findPreference(DELETE_LIMIT).summary =
getString(DELETE_LIMIT, "10")
findPreference(LIST).summary =
(findPreference(LIST) as ListPreference).let {
val ind = Math.max(0, it.findIndexOfValue(
it.value))
resources.getStringArray(listentries)[ind]
}
findPreference(RINGTONE).summary =
getRingtoneName(
Uri.parse(getString(RINGTONE, "") ?: ""))
}
}
fun getRingtoneName(uri:Uri):String {
return activity.contentResolver.
query(uri, null, null, null, null)?.let {
it.moveToFirst()
val res = it.getString(
it.getColumnIndex(
MediaStore.MediaColumns.TITLE))
it.close()
res
} ?: ""
}
}

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187
CHAPTER 8: APIs
This defines a fragment that has the following parameters:

On creation, it sets the preferences resource, as described in a moment.

On creation, it accesses the preferences API using the 
PreferenceManager. We use it to set a preferences change listener, so 
we can update the UI when preferences change. In addition, we fetch a 
couple of preferences to prepare the preferences UI and set “summary” 
lines that get shown inside preference items.

The listener onSharedPreferenceChanged() is used to update the 
summary lines for applicable preferences.
The actual preferences layout gets defined inside res/xml/, in this case, as a resources file 
preferences.xml with these contents:

"http://schemas.android.com/apk/res/android">
android:key="pref_key_auto_delete"
android:summary="Auto delete"
android:title="Auto delete"
android:defaultValue="false" />
android:key="pref_key_delete_limit"
android:dependency="pref_key_auto_delete"
android:summary="Delete Limit"
android:title="Delete Limit"
android:defaultValue="10" />
android:summary="A List"
android:title="A List"
android:entries="@array/listentries"
android:entryValues="@array/listvalues"
android:defaultValue="1" />
android:key="pref_key_mslist"
android:summary="A Multiselect List"
android:title="A Multiselect List"
android:entries="@array/listentries"
android:entryValues="@array/listvalues"
android:defaultValue="@array/multiselectdefaults"/>
android:key="pref_key_switch"
android:summary="A Switch"
android:title="A Switch"
android:defaultValue="false" />
android:key="pref_key_ringtone"
android:summary="A Ringtone"
android:title="A ringtone"
/>

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