[MaterialDatePicker] Fix hint for Korean

PiperOrigin-RevId: 520025180

Author: paulfthomas

lib/java/com/google/android/material/datepicker/UtcDates.java

@@ -172,6 +172,11 @@ static String getDefaultTextInputHint(Resources res, SimpleDateFormat format) {
       formatHint = formatHint.replace("y", "yyyy");
     }
 
+    // Remove duplicate year characters for Korean.
+    if (Locale.getDefault().getLanguage().equals(Locale.KOREAN.getLanguage())) {
+      formatHint = formatHint.replaceAll("y+", "y");
+    }
+
     return formatHint.replace("d", dayChar).replace("M", monthChar).replace("y", yearChar);
   }
 

lib/javatests/com/google/android/material/datepicker/UtcDatesTest.java

@@ -74,4 +74,13 @@ public void textInputHintWith1CharYearLocalized() {
 
     assertEquals("m/j/aaaa", hint);
   }
+
+  @Test
+  @Config(qualifiers = "ko")
+  public void textInputHintForKorean() {
+    SimpleDateFormat sdf = new SimpleDateFormat("yy.M.d.");
+    String hint = UtcDates.getDefaultTextInputHint(context.getResources(), sdf);
+
+    assertEquals("년.월.일.", hint);
+  }
 }