Refactor Pattern.compile calls to static final fields

config/checkstyle/checkstyle.xml

@@ -70,6 +70,17 @@
         <property name="fileExtensions" value="groovy,java" />
     </module>
 
+    <!-- Detect Pattern.compile() with a string literal argument outside a static final field declaration.
+         Use a private static final Pattern field instead to avoid recompiling on every invocation.
+         Dynamic patterns (where the argument is a variable or concatenation) are intentionally excluded.
+         Limitation: patterns where the word "static" appears inside the string literal itself would not be flagged. -->
+    <module name="RegexpSingleline">
+        <property name="id" value="PatternCompileToStaticField"/>
+        <property name="message" value="Pattern.compile() with a string literal argument should be a private static final Pattern field to avoid recompiling on every call." />
+        <property name="format" value="^(?!\s*[/*])(?!.*\bstatic\b).*Pattern\.compile\s*\(\s*&quot;(?:[^&quot;\\]|\\.)*&quot;\s*[,)]" />
+        <property name="fileExtensions" value="java" />
+    </module>
+
     <!-- Checks for size violations: https://checkstyle.sourceforge.io/config_sizes.html -->
 
     <!-- LineLength not in place as PreviewerViewer and RelatedArticlesTab have line length with more than 500 charachters -->

jabgui/src/main/java/org/jabref/gui/maintable/ExtractReferencesAction.java

@@ -39,6 +39,8 @@
 ///
 /// The mode is selected by the preferences whether to use Grobid or not.
 public class ExtractReferencesAction extends SimpleCommand {
+    private static final Pattern COMMENT_NUMBER_PATTERN = Pattern.compile("^\\[(\\d+)\\]");
+
     private final int FILES_LIMIT = 10;
 
     private final DialogService dialogService;
@@ -182,8 +184,7 @@ private static String getCites(List<BibEntry> entries, BibEntry currentEntry) {
                 String newCitationKey;
                 // Could happen if no author and no year is present
                 // We use the number of the comment field (because there is no other way to get the number reliable)
-                Pattern pattern = Pattern.compile("^\\[(\\d+)\\]");
-                Matcher matcher = pattern.matcher(importedEntry.getField(StandardField.COMMENT).orElse(""));
+                Matcher matcher = COMMENT_NUMBER_PATTERN.matcher(importedEntry.getField(StandardField.COMMENT).orElse(""));
                 if (matcher.hasMatch()) {
                     newCitationKey = sourceCitationKey + "-" + matcher.group(1);
                 } else {

jabgui/src/main/java/org/jabref/gui/preferences/preview/PreviewTabViewModel.java

@@ -62,6 +62,9 @@
 public class PreviewTabViewModel implements PreferenceTabViewModel {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(PreviewTabViewModel.class);
+    private static final Pattern XML_TAG_PATTERN = Pattern.compile("(?<ELEMENT>(</?\\h*)(\\w+)([^<>]*)(\\h*/?>))"
+            + "|(?<COMMENT><!--[^<>]+-->)");
+    private static final Pattern XML_ATTRIBUTES_PATTERN = Pattern.compile("(\\w+\\h*)(=)(\\h*\"[^\"]+\")");
 
     private final BooleanProperty showAsExtraTabProperty = new SimpleBooleanProperty(false);
     private final BooleanProperty showPreviewInEntryTableTooltip = new SimpleBooleanProperty(false);
@@ -330,10 +333,6 @@ public void resetDefaultLayout() {
     /// @param text to parse and highlight
     /// @return highlighted span for codeArea
     public StyleSpans<Collection<String>> computeHighlighting(String text) {
-        final Pattern XML_TAG = Pattern.compile("(?<ELEMENT>(</?\\h*)(\\w+)([^<>]*)(\\h*/?>))"
-                + "|(?<COMMENT><!--[^<>]+-->)");
-        final Pattern ATTRIBUTES = Pattern.compile("(\\w+\\h*)(=)(\\h*\"[^\"]+\")");
-
         final int GROUP_OPEN_BRACKET = 2;
         final int GROUP_ELEMENT_NAME = 3;
         final int GROUP_ATTRIBUTES_SECTION = 4;
@@ -342,7 +341,7 @@ public StyleSpans<Collection<String>> computeHighlighting(String text) {
         final int GROUP_EQUAL_SYMBOL = 2;
         final int GROUP_ATTRIBUTE_VALUE = 3;
 
-        Matcher matcher = XML_TAG.matcher(text);
+        Matcher matcher = XML_TAG_PATTERN.matcher(text);
         int lastKeywordEnd = 0;
         StyleSpansBuilder<Collection<String>> spansBuilder = new StyleSpansBuilder<>();
         while (matcher.find()) {
@@ -359,7 +358,7 @@ public StyleSpans<Collection<String>> computeHighlighting(String text) {
                     if (!attributesText.isEmpty()) {
                         lastKeywordEnd = 0;
 
-                        Matcher attributesMatcher = ATTRIBUTES.matcher(attributesText);
+                        Matcher attributesMatcher = XML_ATTRIBUTES_PATTERN.matcher(attributesText);
                         while (attributesMatcher.find()) {
                             spansBuilder.add(List.of(), attributesMatcher.start() - lastKeywordEnd);
                             spansBuilder.add(Set.of("attribute"), attributesMatcher.end(GROUP_ATTRIBUTE_NAME) - attributesMatcher.start(GROUP_ATTRIBUTE_NAME));

jablib/src/main/java/org/jabref/logic/ai/chatting/FollowUpQuestionGenerator.java

@@ -18,6 +18,7 @@ public class FollowUpQuestionGenerator {
     private static final Logger LOGGER = LoggerFactory.getLogger(FollowUpQuestionGenerator.class);
     private static final int MIN_QUESTION_LENGTH = 5;
     private static final int MAX_QUESTION_LENGTH = 100;
+    private static final Pattern NUMBERED_PATTERN = Pattern.compile("^\\s*\\d+\\.\\s*(.+)$", Pattern.MULTILINE);
 
     private final ChatModel chatLanguageModel;
     private final AiTemplatesService aiTemplatesService;
@@ -58,8 +59,7 @@ private String buildPrompt(String userMessage, String aiResponse) {
     private List<String> parseQuestions(String response) {
         List<String> questions = new ArrayList<>();
 
-        Pattern numberedPattern = Pattern.compile("^\\s*\\d+\\.\\s*(.+)$", Pattern.MULTILINE);
-        Matcher matcher = numberedPattern.matcher(response);
+        Matcher matcher = NUMBERED_PATTERN.matcher(response);
 
         while (matcher.find() && questions.size() < aiPreferences.getFollowUpQuestionsCount()) {
             String question = matcher.group(1).trim();

jablib/src/main/java/org/jabref/logic/importer/fileformat/CoinsParser.java

@@ -20,15 +20,15 @@
 /// implemented by reverse-engineering <a href="https://github.com/SeerLabs/CiteSeerX/blob/4df28a98083be2829ec4c56ebbac09eb7772d379/src/java/edu/psu/citeseerx/domain/BiblioTransformer.java#L155-L249">the implementation by CiteSeerX</a>
 public class CoinsParser implements Parser {
 
-    private final Pattern DOI = Pattern.compile("%3Fdoi%3D([^&]+)");
-    private final Pattern TITLE = Pattern.compile("&amp;rft.atitle=([^&]+)");
-    private final Pattern JOURNAL = Pattern.compile("&amp;rft.jtitle=([^&]+)");
-    private final Pattern YEAR = Pattern.compile("&amp;rft.date=([^&]+)");
-    private final Pattern VOLUME = Pattern.compile("&amp;rft.volume=([^&]+)");
-    private final Pattern PAGES = Pattern.compile("&amp;rft.pages=([^&]+)");
-    private final Pattern ISSUE = Pattern.compile("&amp;rft.issue=([^&]+)");
-    private final Pattern TYPE = Pattern.compile("&amp;rft.genre=([^&]+)");
-    private final Pattern AUTHOR = Pattern.compile("&amp;rft.au=([^&]+)");
+    private static final Pattern DOI = Pattern.compile("%3Fdoi%3D([^&]+)");
+    private static final Pattern TITLE = Pattern.compile("&amp;rft.atitle=([^&]+)");
+    private static final Pattern JOURNAL = Pattern.compile("&amp;rft.jtitle=([^&]+)");
+    private static final Pattern YEAR = Pattern.compile("&amp;rft.date=([^&]+)");
+    private static final Pattern VOLUME = Pattern.compile("&amp;rft.volume=([^&]+)");
+    private static final Pattern PAGES = Pattern.compile("&amp;rft.pages=([^&]+)");
+    private static final Pattern ISSUE = Pattern.compile("&amp;rft.issue=([^&]+)");
+    private static final Pattern TYPE = Pattern.compile("&amp;rft.genre=([^&]+)");
+    private static final Pattern AUTHOR = Pattern.compile("&amp;rft.au=([^&]+)");
 
     @Override
     public List<BibEntry> parseEntries(InputStream inputStream) throws ParseException {

jablib/src/main/java/org/jabref/logic/integrity/PagesChecker.java

@@ -34,13 +34,16 @@ public class PagesChecker implements ValueChecker {
                     + ")?"
                     + "\\z";            // end String
 
+    private static final Predicate<String> IS_VALID_PAGE_NUMBER_BIBTEX = Pattern.compile(PAGES_EXP_BIBTEX).asPredicate();
+    private static final Predicate<String> IS_VALID_PAGE_NUMBER_BIBLATEX = Pattern.compile(PAGES_EXP_BIBLATEX).asPredicate();
+
     private final Predicate<String> isValidPageNumber;
 
     public PagesChecker(BibDatabaseContext databaseContext) {
         if (databaseContext.isBiblatexMode()) {
-            isValidPageNumber = Pattern.compile(PAGES_EXP_BIBLATEX).asPredicate();
+            isValidPageNumber = IS_VALID_PAGE_NUMBER_BIBLATEX;
         } else {
-            isValidPageNumber = Pattern.compile(PAGES_EXP_BIBTEX).asPredicate();
+            isValidPageNumber = IS_VALID_PAGE_NUMBER_BIBTEX;
         }
     }
 

jablib/src/main/java/org/jabref/logic/msbib/MSBibEntry.java

@@ -26,6 +26,13 @@
 /// @see <a href="http://www.ecma-international.org/publications/standards/Ecma-376.htm">ECMA Standard</a>
 class MSBibEntry {
 
+    /// reduced subset, supports only "CITY , STATE, COUNTRY" <br>
+    /// **\b(\w+)\s?[,]?\s?(\w+)\s?[,]?\s?(\w*)\b** <br>
+    /// WORD SPACE , SPACE WORD SPACE (Can be zero or more) , SPACE WORD (Can be zero or more) <br>
+    /// Matches both single locations (only city) like Berlin and full locations like Stroudsburg, PA, USA <br>
+    /// tested using http://www.regexpal.com/
+    private static final Pattern ADDRESS_PATTERN = Pattern.compile("\\b(\\w+)\\s?[,]?\\s?(\\w*)\\s?[,]?\\s?(\\w*)\\b");
+
     public Map<String, String> fields = new HashMap<>();
 
     public List<MsBibAuthor> authors;
@@ -65,13 +72,6 @@ class MSBibEntry {
 
     private String bibtexEntryType;
 
-    /// reduced subset, supports only "CITY , STATE, COUNTRY" <br>
-    /// **\b(\w+)\s?[,]?\s?(\w+)\s?[,]?\s?(\w*)\b** <br>
-    /// WORD SPACE , SPACE WORD SPACE (Can be zero or more) , SPACE WORD (Can be zero or more) <br>
-    /// Matches both single locations (only city) like Berlin and full locations like Stroudsburg, PA, USA <br>
-    /// tested using http://www.regexpal.com/
-    private final Pattern ADDRESS_PATTERN = Pattern.compile("\\b(\\w+)\\s?[,]?\\s?(\\w*)\\s?[,]?\\s?(\\w*)\\b");
-
     public MSBibEntry() {
         // empty
     }

jablib/src/main/java/org/jabref/logic/openoffice/oocsltext/CSLCitationOOAdapter.java

@@ -40,6 +40,7 @@
 public class CSLCitationOOAdapter {
 
     private static final CitationStyleOutputFormat HTML_OUTPUT_FORMAT = CitationStyleOutputFormat.HTML;
+    private static final Pattern CITATION_NUMBER_PATTERN = Pattern.compile("(\\D*)(\\d+)(\\D*)");
 
     private final XTextDocument document;
     private final CSLReferenceMarkManager markManager;
@@ -259,8 +260,7 @@ private void insertReferences(XTextCursor cursor, List<BibEntry> entries, OOText
 
     /// Transforms the numbers in the citation to globally-unique (and thus, reusable) numbers.
     private String updateSingleOrMultipleCitationNumbers(String citation, List<BibEntry> entries) {
-        Pattern pattern = Pattern.compile("(\\D*)(\\d+)(\\D*)");
-        Matcher matcher = pattern.matcher(citation);
+        Matcher matcher = CITATION_NUMBER_PATTERN.matcher(citation);
         StringBuilder sb = new StringBuilder();
         Iterator<BibEntry> iterator = entries.iterator();
 

jablib/src/main/java/org/jabref/logic/openoffice/oocsltext/CSLFormatUtils.java

@@ -48,6 +48,7 @@ public final class CSLFormatUtils {
     private static final String DEFAULT_HANGING_INDENT_BIBLIOGRAPHY_BODY_FORMAT = "Hanging indent";
 
     private static final Pattern YEAR_IN_CITATION_PATTERN = Pattern.compile("(.)(.*), (\\d{4}.*)");
+    private static final Pattern BIBLIOGRAPHY_NUMBER_PATTERN = Pattern.compile("([\\[(])?(\\d+)([])])?(\\.)?\\s*");
 
     private CSLFormatUtils() {
         // prevent instantiation
@@ -168,8 +169,7 @@ public static String generateAlphanumericInTextCitation(BibEntry entry, BibDatab
     /// @param currentNumber the correct number to update the citation with.
     /// @return the bibliographic citation with resolved number.
     public static String updateSingleBibliographyNumber(String citation, int currentNumber) {
-        Pattern pattern = Pattern.compile("([\\[(])?(\\d+)([])])?(\\.)?\\s*");
-        Matcher matcher = pattern.matcher(citation);
+        Matcher matcher = BIBLIOGRAPHY_NUMBER_PATTERN.matcher(citation);
         StringBuilder sb = new StringBuilder();
         boolean numberReplaced = false;
 

jablib/src/main/java/org/jabref/logic/openoffice/oocsltext/CSLReferenceMarkManager.java

@@ -40,6 +40,7 @@
 /// Class for generation, insertion and management of all reference marks in the document.
 public class CSLReferenceMarkManager {
     private static final Logger LOGGER = LoggerFactory.getLogger(CSLReferenceMarkManager.class);
+    private static final Pattern CITATION_NUMBER_PATTERN = Pattern.compile("(\\D*)(\\d+)(\\D*)");
 
     private final XTextDocument document;
     private final XMultiServiceFactory factory;
@@ -227,8 +228,7 @@ private void updateAllCitationNumbers() throws Exception, CreationException {
     }
 
     private String getUpdatedCitationTextWithNewNumbers(String currentText, List<Integer> newNumbers) {
-        Pattern pattern = Pattern.compile("(\\D*)(\\d+)(\\D*)");
-        Matcher matcher = pattern.matcher(currentText);
+        Matcher matcher = CITATION_NUMBER_PATTERN.matcher(currentText);
         StringBuilder result = new StringBuilder();
         int lastEnd = 0;
         int numberIndex = 0;

jablib/src/main/java/org/jabref/logic/util/strings/StringUtil.java

@@ -49,6 +49,8 @@ public class StringUtil {
     private static final UnicodeToReadableCharMap UNICODE_CHAR_MAP = new UnicodeToReadableCharMap();
     private static final String WRAPPED_LINE_PREFIX = ""; // If a line break is added, this prefix will be inserted at the beginning of the next line
     private static final String STRING_TABLE_DELIMITER = " : ";
+    // A sentence ends with a .?!;, but not in the case of "Mr.", "Ms.", "Mrs.", "Dr.", "st.", "jr.", "co.", "inc.", and "ltd."
+    private static final Pattern SPLIT_TEXT_PATTERN = Pattern.compile("(?<=[\\.!;\\?])(?<![Mm](([Rr]|[Rr][Ss])|[Ss])\\.|[Dd][Rr]\\.|[Ss][Tt]\\.|[Jj][Rr]\\.|[Cc][Oo]\\.|[Ii][Nn][Cc]\\.|[Ll][Tt][Dd]\\.)\\s+");
 
     public static String booleanToBinaryString(boolean expression) {
         return expression ? "1" : "0";
@@ -676,9 +678,7 @@ public static List<String> getStringAsWords(String text) {
 
     /// Returns a list of sentences contained in the given text.
     public static List<String> getStringAsSentences(String text) {
-        // A sentence ends with a .?!;, but not in the case of "Mr.", "Ms.", "Mrs.", "Dr.", "st.", "jr.", "co.", "inc.", and "ltd."
-        Pattern splitTextPattern = Pattern.compile("(?<=[\\.!;\\?])(?<![Mm](([Rr]|[Rr][Ss])|[Ss])\\.|[Dd][Rr]\\.|[Ss][Tt]\\.|[Jj][Rr]\\.|[Cc][Oo]\\.|[Ii][Nn][Cc]\\.|[Ll][Tt][Dd]\\.)\\s+");
-        return Arrays.asList(splitTextPattern.split(text));
+        return Arrays.asList(SPLIT_TEXT_PATTERN.split(text));
     }
 
     @AllowedToUseApacheCommonsLang3("No direct Guava equivalent existing - see https://stackoverflow.com/q/16560635/873282")

jablib/src/main/java/org/jabref/model/entry/identifier/ArXivIdentifier.java

@@ -20,6 +20,8 @@ public class ArXivIdentifier extends EprintIdentifier {
 
     private static final String ARXIV_PREFIX = "http(s)?://arxiv.org/(abs|html|pdf)/|arxiv|arXiv";
     private static final Pattern IDENTIFIER_PATTERN = Pattern.compile("(" + ARXIV_PREFIX + ")?\\s?:?\\s?(?<id>\\d{4}\\.\\d{4,5})(v(?<version>\\d+))?\\s?(\\[(?<classification>\\S+)\\])?");
+    private static final Pattern OLD_IDENTIFIER_PATTERN = Pattern.compile("(" + ARXIV_PREFIX + ")?\\s?:?\\s?(?<id>(?<classification>[a-z\\-]+(\\.[A-Z]{2})?)/\\d{7})(v(?<version>\\d+))?");
+
     private final String identifier;
     private final String classification;
     private final String version;
@@ -45,8 +47,7 @@ public static Optional<ArXivIdentifier> parse(String value) {
             return getArXivIdentifier(identifierMatcher);
         }
 
-        Pattern oldIdentifierPattern = Pattern.compile("(" + ARXIV_PREFIX + ")?\\s?:?\\s?(?<id>(?<classification>[a-z\\-]+(\\.[A-Z]{2})?)/\\d{7})(v(?<version>\\d+))?");
-        Matcher oldIdentifierMatcher = oldIdentifierPattern.matcher(identifier);
+        Matcher oldIdentifierMatcher = OLD_IDENTIFIER_PATTERN.matcher(identifier);
         if (oldIdentifierMatcher.matches()) {
             return getArXivIdentifier(oldIdentifierMatcher);
         }

jablib/src/main/java/org/jabref/model/entry/identifier/IacrEprint.java

@@ -18,16 +18,19 @@
 @AllowedToUseLogic("Because URL utility is needed")
 public class IacrEprint implements Identifier {
     public static final URI RESOLVER = URLUtil.createUri("https://ia.cr");
+
     private static final Logger LOGGER = LoggerFactory.getLogger(IacrEprint.class);
 
     private static final String IACR_EPRINT_EXP = "\\d{4}\\/\\d{3,5}";
+    private static final Pattern IACR_EPRINT_PATTERN = Pattern.compile(IACR_EPRINT_EXP);
+
     private final String iacrEprint;
 
     IacrEprint(@NonNull String iacrEprint) {
         String trimmedId = iacrEprint.trim();
 
         if (matchesExcepted(trimmedId)) {
-            Matcher matcher = Pattern.compile(IACR_EPRINT_EXP).matcher(trimmedId);
+            Matcher matcher = IACR_EPRINT_PATTERN.matcher(trimmedId);
             matcher.find();
             this.iacrEprint = matcher.group(0);
         } else {

jablib/src/test/java/org/jabref/logic/importer/ImporterTest.java

@@ -33,6 +33,8 @@
 @ResourceLock("Localization.lang")
 public class ImporterTest {
 
+    private static final Pattern WHITESPACE_PATTERN = Pattern.compile("\\s");
+
     @ParameterizedTest
     @MethodSource("instancesToTest")
     void getFormatterNameDoesNotReturnNull(Importer format) {
@@ -54,8 +56,7 @@ void getIdDoesNotReturnNull(Importer format) {
     @ParameterizedTest
     @MethodSource("instancesToTest")
     void getIdDoesNotContainWhitespace(Importer format) {
-        Pattern whitespacePattern = Pattern.compile("\\s");
-        assertFalse(whitespacePattern.matcher(format.getId()).find());
+        assertFalse(WHITESPACE_PATTERN.matcher(format.getId()).find());
     }
 
     @ParameterizedTest

jabls/src/main/java/org/jabref/languageserver/util/definition/MarkdownDefinitionProvider.java

@@ -6,9 +6,12 @@
 
 public class MarkdownDefinitionProvider extends DefinitionProvider {
 
+    private static final Pattern CITATION_COMMAND_PATTERN = Pattern.compile("(?<keys>\\[[^\\]]*@[^\\]]*\\]|@[a-z0-9_.+:-]+(?:\\s*;\\s*@[a-z0-9_.+:-]+)*)", Pattern.CASE_INSENSITIVE);
+    private static final Pattern CITATION_KEY_INSIDE_PATTERN = Pattern.compile("@(?<citationkey>[a-z0-9_.+:-]+)", Pattern.CASE_INSENSITIVE);
+
     public MarkdownDefinitionProvider(LspParserHandler parserHandler) {
         super(parserHandler);
-        this.citationCommandPattern = Pattern.compile("(?<keys>\\[[^\\]]*@[^\\]]*\\]|@[a-z0-9_.+:-]+(?:\\s*;\\s*@[a-z0-9_.+:-]+)*)", Pattern.CASE_INSENSITIVE);
-        this.citationKeyInsidePattern = Pattern.compile("@(?<citationkey>[a-z0-9_.+:-]+)", Pattern.CASE_INSENSITIVE);
+        this.citationCommandPattern = CITATION_COMMAND_PATTERN;
+        this.citationKeyInsidePattern = CITATION_KEY_INSIDE_PATTERN;
     }
 }