Android patch: Allow duplicated fields in DateTimePatternGenerator

The original patch can be found at
https://r.android.com/1458480

A skeleton, e.g. "jmma", is mapped into "ahmma" internally
by #mapSkeletonMetacharacters, and thus the internal skeleton
has duplicated fields "a".

This is a regression when we moved the implementation of
android.text.format.DateFormat#getBestPattern() from
udatpg_getBestPattern in ICU4C to ICU4j DateTimePatternGenerator
in the CL https://r.android.com/1355735.
The expected pattern generated from skeleton of "jmma" is
"h:mm a".

Bug: 170233598
Test: n/a
Change-Id: I532956cb8ec85e093d1174fc84e915bd16e7248e

1 files changed, 20 insertions, 2 deletions

diff --git a/icu4j/main/core/src/main/java/com/ibm/icu/text/DateTimePatternGenerator.java b/icu4j/main/core/src/main/java/com/ibm/icu/text/DateTimePatternGenerator.java
index d66b478b0..f2fff195e 100644
--- a/icu4j/main/core/src/main/java/com/ibm/icu/text/DateTimePatternGenerator.java
+++ b/icu4j/main/core/src/main/java/com/ibm/icu/text/DateTimePatternGenerator.java
@@ -630,16 +630,34 @@ public class DateTimePatternGenerator implements Freezable<DateTimePatternGenera
         return getBestPattern(skeleton, null, options);
     }
 
+    // BEGIN Android-added: http://b/170233598 Allow duplicate fields
+    /**
+     * @internal
+     */
+    public String getBestPattern(String skeleton, boolean allowDuplicateFields) {
+        return getBestPattern(skeleton, null, MATCH_NO_OPTIONS, allowDuplicateFields);
+    }
+
+    private String getBestPattern(String skeleton, DateTimeMatcher skipMatcher, int options) {
+        return getBestPattern(skeleton, skipMatcher, options, false);
+    }
+    // END Android-added: http://b/170233598 Allow duplicate fields
+
     /*
      * getBestPattern which takes optional skip matcher
      */
-    private String getBestPattern(String skeleton, DateTimeMatcher skipMatcher, int options) {
+    // Android-changed: http://b/170233598 Allow duplicate fields
+    // private String getBestPattern(String skeleton, DateTimeMatcher skipMatcher, int options) {
+    private String getBestPattern(String skeleton, DateTimeMatcher skipMatcher, int options,
+            boolean allowDuplicateFields) {
         EnumSet<DTPGflags> flags = EnumSet.noneOf(DTPGflags.class);
         // Replace hour metacharacters 'j', 'C', and 'J', set flags as necessary
         String skeletonMapped = mapSkeletonMetacharacters(skeleton, flags);
         String datePattern, timePattern;
         synchronized(this) {
-            current.set(skeletonMapped, fp, false);
+            // Android-changed: http://b/170233598 Allow duplicate fields
+            // current.set(skeletonMapped, fp, false);
+            current.set(skeletonMapped, fp, allowDuplicateFields);
             PatternWithMatcher bestWithMatcher = getBestRaw(current, -1, _distanceInfo, skipMatcher);
             if (_distanceInfo.missingFieldMask == 0 && _distanceInfo.extraFieldMask == 0) {
                 // we have a good item. Adjust the field types