Fix warning display issue for entering a title made of two words

CHANGELOG.md

@@ -47,6 +47,7 @@ We refer to [GitHub issues](https://github.com/JabRef/jabref/issues) by using `#
 - We fixed an issue where the group and the link column were not updated after changing the entry in the main table. [#5985](https://github.com/JabRef/jabref/issues/5985)
 - We fixed an issue where reordering the groups was not possible after inserting an article. [#6008](https://github.com/JabRef/jabref/issues/6008)
 - We fixed an issue where citation styles except the default "Preview" could not be used. [#56220](https://github.com/JabRef/jabref/issues/5622)
+- We fixed an issue where warning is displayed when title is made of two sentences. [#5832](https://github.com/JabRef/jabref/issues/5832)
 
 ### Removed
 

src/main/java/org/jabref/logic/integrity/TitleChecker.java

@@ -12,6 +12,7 @@
 public class TitleChecker implements ValueChecker {
 
     private static final Pattern INSIDE_CURLY_BRAKETS = Pattern.compile("\\{[^}\\{]*\\}");
+    private static final String DELIMITERS = "(\\.|\\!|\\?|\\;|\\:)";
     private static final Predicate<String> HAS_CAPITAL_LETTERS = Pattern.compile("[\\p{Lu}\\p{Lt}]").asPredicate();
 
     private final BibDatabaseContext databaseContext;
@@ -22,10 +23,12 @@ public TitleChecker(BibDatabaseContext databaseContext) {
 
     /**
      * Algorithm:
-     * - remove trailing whitespaces
-     * - ignore first letter as this can always be written in caps
      * - remove everything that is in brackets
-     * - check if at least one capital letter is in the title
+     * - split the title into subTitles based on the delimiters
+     * - for each subTitle:
+     * -    remove trailing whitespaces
+     * -    ignore first letter as this can always be written in caps
+     * -    check if at least one capital letter is in the title
      */
     @Override
     public Optional<String> checkValue(String value) {
@@ -37,9 +40,7 @@ public Optional<String> checkValue(String value) {
             return Optional.empty();
         }
 
-        String valueTrimmed = value.trim();
-        String valueIgnoringFirstLetter = valueTrimmed.startsWith("{") ? valueTrimmed : valueTrimmed.substring(1);
-        String valueOnlySpacesWithinCurlyBraces = valueIgnoringFirstLetter;
+        String valueOnlySpacesWithinCurlyBraces = value;
         while (true) {
             Matcher matcher = INSIDE_CURLY_BRAKETS.matcher(valueOnlySpacesWithinCurlyBraces);
             if (!matcher.find()) {
@@ -48,11 +49,16 @@ public Optional<String> checkValue(String value) {
             valueOnlySpacesWithinCurlyBraces = matcher.replaceAll("");
         }
 
-        boolean hasCapitalLettersThatBibtexWillConvertToSmallerOnes = HAS_CAPITAL_LETTERS
-                .test(valueOnlySpacesWithinCurlyBraces);
-
-        if (hasCapitalLettersThatBibtexWillConvertToSmallerOnes) {
-            return Optional.of(Localization.lang("capital letters are not masked using curly brackets {}"));
+        // Delimiters are . ! ? ; :
+        String[] splitTitle = valueOnlySpacesWithinCurlyBraces.split(DELIMITERS);
+        for (String subTitle : splitTitle) {
+            subTitle = subTitle.trim();
+            if (subTitle.length() > 0) {
+                subTitle = subTitle.substring(1);
+            }
+            if (HAS_CAPITAL_LETTERS.test(subTitle)) {
+                return Optional.of(Localization.lang("capital letters are not masked using curly brackets {}"));
+            }
         }
 
         return Optional.empty();