I've made a nice way to detect and update the UI whenever needed, when the date has changed. It's based on the broadcastReceiver, which should be registered on the onStart method, and unregistered on the onStop method (unregistration is done automatically in my code).
build.gradle
implementation 'com.jakewharton.threetenabp:threetenabp:1.0.5'
LocalDateEx.kt
object LocalDateEx {
/**an alternative of LocalDate.now(), as it requires initialization using AndroidThreeTen.init(context), which takes a bit time (loads a file)*/
@JvmStatic
fun getNow(): LocalDate = Calendar.getInstance().toLocalDate()
}
fun Calendar.toLocalDate(): LocalDate = LocalDate.of(get(Calendar.YEAR), get(Calendar.MONTH) + 1, get(Calendar.DAY_OF_MONTH))
DateChangedBroadcastReceiver.kt
abstract class DateChangedBroadcastReceiver : BroadcastReceiver() {
private var curDate = LocalDateEx.getNow()
/**called when the receiver detected the date has changed. You should still check it yourself, because you might already be synced with the new date*/
abstract fun onDateChanged(previousDate: LocalDate, newDate: LocalDate)
@Suppress("MemberVisibilityCanBePrivate")
fun register(context: Context, date: LocalDate) {
curDate = date
val filter = IntentFilter()
filter.addAction(Intent.ACTION_TIME_CHANGED)
filter.addAction(Intent.ACTION_DATE_CHANGED)
filter.addAction(Intent.ACTION_TIMEZONE_CHANGED)
context.registerReceiver(this, filter)
val newDate = LocalDateEx.getNow()
if (newDate != curDate) {
curDate = newDate
onDateChanged(date, newDate)
}
}
/**a convenient way to auto-unregister when activity/fragment has stopped. This should be called on the onStart method of the fragment/activity*/
fun registerOnStart(activity: AppCompatActivity, date: LocalDate, fragment: Fragment? = null) {
register(activity, date)
val lifecycle = fragment?.lifecycle ?: activity.lifecycle
lifecycle.addObserver(object : LifecycleObserver {
@OnLifecycleEvent(Lifecycle.Event.ON_STOP)
fun onStop() {
Log.d("AppLog", "onStop, so unregistering")
lifecycle.removeObserver(this)
activity.unregisterReceiver(this@DateChangedBroadcastReceiver)
}
})
}
override fun onReceive(context: Context, intent: Intent) {
val newDate = LocalDateEx.getNow()
Log.d("AppLog", "got intent:" + intent.action + " curDate:" + curDate + " newDate:" + newDate)
if (newDate != curDate) {
Log.d("AppLog", "cur date is different, so posting event")
val previousDate = curDate
curDate = newDate
onDateChanged(previousDate, newDate)
}
}
}
MainActivity.kt
class MainActivity : AppCompatActivity() {
var today = LocalDateEx.getNow()
val receiver = object : DateChangedBroadcastReceiver() {
override fun onDateChanged(previousDate: LocalDate, newDate: LocalDate) {
Log.d("AppLog", "onDateChangedEvent:" + newDate + " previousDate:" + previousDate)
if (newDate != today) {
today = newDate
textView.text = "date updated:" + today
}
}
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
Log.d("AppLog", "onCreate")
setContentView(R.layout.activity_main)
textView.text = today.toString()
}
override fun onStart() {
super.onStart()
receiver.registerOnStart(this, today)
}
}
activity_main.xml
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity">
<TextView
android:id="@+id/textView" android:layout_width="wrap_content" android:layout_height="wrap_content"
android:layout_gravity="center"/>
</FrameLayout>
Alternative to the above, using Android's Calendar class only, without the need to use another library:
fun Calendar.equalInDateAlone(cal: Calendar): Boolean =
get(Calendar.YEAR) == cal.get(Calendar.YEAR) && get(Calendar.MONTH) == cal.get(Calendar.MONTH) && get(Calendar.DAY_OF_MONTH) == cal.get(Calendar.DAY_OF_MONTH)
fun Calendar.resetTimeFields(): Calendar {
set(Calendar.HOUR_OF_DAY, 0)
set(Calendar.SECOND, 0)
set(Calendar.MINUTE, 0)
set(Calendar.MILLISECOND, 0)
return this
}
abstract class DateChangedBroadcastReceiver : BroadcastReceiver() {
private var curDate = Calendar.getInstance().resetTimeFields()
/**called when the receiver detected the date has changed. You should still check it yourself, because you might already be synced with the new date*/
abstract fun onDateChanged(previousDate: Calendar, newDate: Calendar)
@Suppress("MemberVisibilityCanBePrivate")
fun register(context: Context, date: Calendar) {
curDate = (date.clone() as Calendar).resetTimeFields()
val filter = IntentFilter()
filter.addAction(Intent.ACTION_TIME_CHANGED)
filter.addAction(Intent.ACTION_DATE_CHANGED)
filter.addAction(Intent.ACTION_TIMEZONE_CHANGED)
context.registerReceiver(this, filter)
val newDate = Calendar.getInstance().resetTimeFields()
if (!newDate.equalInDateAlone(curDate)) {
curDate = newDate.clone() as Calendar
onDateChanged(date, newDate)
}
}
/**a convenient way to auto-unregister when activity/fragment has stopped. This should be called on the onStart method of the fragment/activity*/
@Suppress("unused")
fun registerOnStart(activity: AppCompatActivity, date: Calendar, fragment: Fragment? = null) {
register(activity, date)
val lifecycle = fragment?.lifecycle ?: activity.lifecycle
lifecycle.addObserver(object : LifecycleObserver {
@OnLifecycleEvent(Lifecycle.Event.ON_STOP)
fun onStop() {
// Log.d("AppLog", "onStop, so unregistering")
lifecycle.removeObserver(this)
activity.unregisterReceiver(this@DateChangedBroadcastReceiver)
}
})
}
override fun onReceive(context: Context, intent: Intent) {
val newDate = Calendar.getInstance().resetTimeFields()
// Log.d("AppLog", "got intent:" + intent.action + " curDate:" + curDate.toSimpleDateString() + " newDate:" + newDate.toSimpleDateString())
if (!newDate.equalInDateAlone(curDate)) {
// Log.d("AppLog", "cur date is different, so posting event")
val previousDate = curDate
curDate = newDate
onDateChanged(previousDate, newDate)
}
}
}
