Handle case that time zone is known in Android, but not in ical4j

2 files changed, 15 insertions, 2 deletions

diff --git a/src/androidTest/java/at/bitfire/ical4android/AndroidCompatTimeZoneRegistryTest.kt b/src/androidTest/java/at/bitfire/ical4android/AndroidCompatTimeZoneRegistryTest.kt
index 5958e16..d4e2209 100644
--- a/src/androidTest/java/at/bitfire/ical4android/AndroidCompatTimeZoneRegistryTest.kt
+++ b/src/androidTest/java/at/bitfire/ical4android/AndroidCompatTimeZoneRegistryTest.kt
@@ -5,6 +5,7 @@
 package at.bitfire.ical4android
 
 import net.fortuna.ical4j.model.DefaultTimeZoneRegistryFactory
+import net.fortuna.ical4j.model.TimeZone
 import net.fortuna.ical4j.model.TimeZoneRegistry
 import org.junit.Assert.*
 import org.junit.Assume
@@ -42,6 +43,18 @@ class AndroidCompatTimeZoneRegistryTest {
     }
 
     @Test
+    fun getTimeZone_Existing_ButNotInIcal4j() {
+        val reg = AndroidCompatTimeZoneRegistry(object: TimeZoneRegistry {
+            override fun register(timezone: TimeZone?) = throw NotImplementedError()
+            override fun register(timezone: TimeZone?, update: Boolean) = throw NotImplementedError()
+            override fun clear() = throw NotImplementedError()
+            override fun getTimeZone(id: String?) = null
+
+        })
+        assertNull(reg.getTimeZone("Europe/Berlin"))
+    }
+
+    @Test
     fun getTimeZone_Existing_Kiev() {
         Assume.assumeFalse(systemKnowsKyiv)
         val tz = registry.getTimeZone("Europe/Kiev")
diff --git a/src/main/java/at/bitfire/ical4android/AndroidCompatTimeZoneRegistry.kt b/src/main/java/at/bitfire/ical4android/AndroidCompatTimeZoneRegistry.kt
index 5f7246d..4030404 100644
--- a/src/main/java/at/bitfire/ical4android/AndroidCompatTimeZoneRegistry.kt
+++ b/src/main/java/at/bitfire/ical4android/AndroidCompatTimeZoneRegistry.kt
@@ -51,8 +51,8 @@ class AndroidCompatTimeZoneRegistry(
            Example: getTimeZone("Europe/Kiev") returns a TimeZone with TZID:Europe/Kyiv since ical4j/3.2.5,
            but most Android devices don't now Europe/Kyiv yet.
            */
-        val tz = base.getTimeZone(id)
-        if (tz.id != androidTzId) {
+        val tz: TimeZone? = base.getTimeZone(id)
+        if (tz != null && tz.id != androidTzId) {
             Ical4Android.log.warning("Using Android TZID $androidTzId instead of ical4j ${tz.id}")
 
             // create a copy of the VTIMEZONE so that we don't modify the original registry values (which are not immutable)