Add String interning for zoneIds am: 8b8c65b972

Original change: https://android-review.googlesource.com/c/platform/external/icu/+/1366781

Change-Id: I5f1447986695590d8e528bb09f57b010abb1bc3f

2 files changed, 23 insertions, 3 deletions

diff --git a/android_icu4j/libcore_bridge/src/java/com/android/i18n/timezone/TimeZoneFinder.java b/android_icu4j/libcore_bridge/src/java/com/android/i18n/timezone/TimeZoneFinder.java
index bf04b1bf9..7676a67d1 100644
--- a/android_icu4j/libcore_bridge/src/java/com/android/i18n/timezone/TimeZoneFinder.java
+++ b/android_icu4j/libcore_bridge/src/java/com/android/i18n/timezone/TimeZoneFinder.java
@@ -369,8 +369,13 @@ public final class TimeZoneFinder {
                         + parser.getPositionDescription());
             }
 
-            TimeZoneMapping timeZoneMapping =
-                    new TimeZoneMapping(zoneIdString, showInPicker, notUsedAfter, alternativeIds);
+            // intern() zone Ids because they are a fixed set of well-known strings that are used in
+            // other low-level library calls.
+            String internedZoneIdString = zoneIdString.intern();
+            List<String> internedAlternativeIds = internStrings(alternativeIds);
+
+            TimeZoneMapping timeZoneMapping = new TimeZoneMapping(
+                    internedZoneIdString, showInPicker, notUsedAfter, internedAlternativeIds);
             timeZoneMappings.add(timeZoneMapping);
         }
 
@@ -378,6 +383,18 @@ public final class TimeZoneFinder {
         return Collections.unmodifiableList(timeZoneMappings);
     }
 
+    private static List<String> internStrings(List<String> stringsToIntern) {
+        if (stringsToIntern.isEmpty()) {
+            return stringsToIntern;
+        }
+
+        List<String> internedStrings = new ArrayList<>(stringsToIntern.size());
+        for (String stringToIntern : stringsToIntern) {
+            internedStrings.add(stringToIntern.intern());
+        }
+        return internedStrings;
+    }
+
     /**
      * Processes &lt;timezones&gt; data.
      */
diff --git a/android_icu4j/libcore_bridge/src/java/com/android/i18n/timezone/ZoneInfoDb.java b/android_icu4j/libcore_bridge/src/java/com/android/i18n/timezone/ZoneInfoDb.java
index 30eee3af8..69155d620 100644
--- a/android_icu4j/libcore_bridge/src/java/com/android/i18n/timezone/ZoneInfoDb.java
+++ b/android_icu4j/libcore_bridge/src/java/com/android/i18n/timezone/ZoneInfoDb.java
@@ -289,7 +289,10 @@ public final class ZoneInfoDb implements AutoCloseable {
       if (len == 0) {
         throw new IOException("Invalid ID at index=" + i);
       }
-      ids[i] = new String(idBytes, 0, len, StandardCharsets.US_ASCII);
+      String zoneId = new String(idBytes, 0, len, StandardCharsets.US_ASCII);
+      // intern() zone Ids because they are a fixed set of well-known strings that are used in
+      // other low-level library calls.
+      ids[i] = zoneId.intern();
       if (i > 0) {
         if (ids[i].compareTo(ids[i - 1]) <= 0) {
           throw new IOException("Index not sorted or contains multiple entries with the same ID"