Add support for German monts at the normalizer functionality

CHANGELOG.md

@@ -15,6 +15,7 @@ We refer to [GitHub issues](https://github.com/JabRef/jabref/issues) by using `#
 - We now show a small notification icon in the entry editor when we detect data inconsistency or other problems. [#3145](https://github.com/JabRef/jabref/issues/3145)
 - We added [oaDOI](https://oadoi.org/) as a fulltext provider, so that JabRef is now able to provide fulltexts for more than 90 million open-access articles.
 - We changed one default of [Cleanup entries dialog](http://help.jabref.org/en/CleanupEntries): Per default, the PDF are not moved to the default file directory anymore. [#3619](https://github.com/JabRef/jabref/issues/3619)
+- We enhanced the cleanup functionality to normalize month names in other languages such as German, too.
 - We added the export of the the `translator` field to the according MS-Office XML field. [#1750, comment](https://github.com/JabRef/jabref/issues/1750#issuecomment-357350986)
 - We changed the import of the MS-Office XML fields `bookauthor` and `translator`. Both are now imported to their corresponding bibtex/biblatex fields.
 - We improved the export of the `address` and `location` field to the MS-Office XML fields. If the address field does not contain a comma, it is treated as single value and exported to the field `city`. [#1750, comment](https://github.com/JabRef/jabref/issues/1750#issuecomment-357539167) 

src/main/java/org/jabref/model/entry/Month.java

@@ -1,7 +1,11 @@
 package org.jabref.model.entry;
 
+import java.text.DateFormatSymbols;
+import java.util.Locale;
+import java.util.Objects;
 import java.util.Optional;
 
+import org.jabref.model.strings.LatexToUnicodeAdapter;
 import org.jabref.model.strings.StringUtil;
 
 /**
@@ -93,8 +97,44 @@ public static Optional<Month> parse(String value) {
             int number = Integer.parseInt(value);
             return Month.getMonthByNumber(number);
         } catch (NumberFormatException e) {
-            return Optional.empty();
+            return parseLocalizedMonth(value);
+        }
+    }
+
+    /**
+     * Parses a month having the string in a localized form such as "Juli"
+     *
+     * @param value the text value - must not me null
+     * @return the corresponding month instance, empty if none was found
+     */
+    private static Optional<Month> parseLocalizedMonth(String value) {
+        Objects.requireNonNull(value);
+
+        // Normalize month name to unicode, which is returned by DateFormatSymbols.getMonths() - see below
+        value = new LatexToUnicodeAdapter().format(value);
+
+        Optional<Month> month = Optional.empty();
+
+        if (value.equalsIgnoreCase("Maerz")) {
+            // this value is not treated by LatexToUnicodeAdapter, so a special handling is required.
+            month = Month.getMonthByNumber(3);
+        } else {
+            Locale[] availableLocales = Locale.getAvailableLocales();
+            int i = 0;
+            do {
+                String[] months = new DateFormatSymbols(availableLocales[i]).getMonths();
+                int j = 0;
+                do {
+                    if (value.equalsIgnoreCase(months[j])) {
+                        month = Month.getMonthByNumber(j + 1);
+                    }
+                    j++;
+                } while (!month.isPresent() && (j < months.length));
+                i++;
+            } while (!month.isPresent() && (i < availableLocales.length));
         }
+
+        return month;
     }
 
     /**

src/test/java/org/jabref/logic/formatter/bibtexfields/NormalizeMonthFormatterTest.java

@@ -21,4 +21,24 @@ public void formatExample() {
         Assert.assertEquals("#dec#", formatter.format(formatter.getExampleInput()));
     }
 
+    @Test
+    public void formatGermanMarch() {
+        Assert.assertEquals("#mar#", formatter.format("Maerz"));
+    }
+
+    @Test
+    public void formatGermanMarchInUtf8() {
+        Assert.assertEquals("#mar#", formatter.format("März"));
+    }
+
+    @Test
+    public void formatGermanMarchInLaTeX() {
+        Assert.assertEquals("#mar#", formatter.format("M\\\"arz"));
+    }
+
+    @Test
+    public void formatGermanMarchInLaTeXWithBraces() {
+        Assert.assertEquals("#mar#", formatter.format("M{\\\"a}rz"));
+    }
+
 }