some small code cleanup, e.g. to make more values final/immutable

languagetool-core/src/main/java/org/languagetool/bitext/StringPair.java

@@ -22,9 +22,8 @@
 /**
  * A convenience class to work with bitext strings.
  * @author Marcin Miłkowski
- *
  */
-public class StringPair {
+public final class StringPair {
 
   private final String sourceString;
   private final String targetString;

languagetool-core/src/main/java/org/languagetool/rules/bitext/BitextRule.java

@@ -21,6 +21,7 @@
 
 import java.io.IOException;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 import org.languagetool.AnalyzedSentence;
@@ -40,28 +41,30 @@
 public abstract class BitextRule extends Rule {
 
   public static List<Class<? extends BitextRule>> getRelevantRules() {
-    return Arrays.asList(DifferentLengthRule.class, SameTranslationRule.class,
-        DifferentPunctuationRule.class);
+    return Arrays.asList(
+            DifferentLengthRule.class,
+            SameTranslationRule.class,
+            DifferentPunctuationRule.class
+    );
   }
 
-  private List<StringPair> correctExamples;
-  private List<IncorrectBitextExample> incorrectExamples;
-
-  private Language sourceLanguage;
-
   @Override
   public abstract String getDescription();
 
-  public abstract String getMessage();
-
   @Override
   public abstract String getId();
 
+  @Override
+  public abstract void reset();
+
+  public abstract String getMessage();
+
   public abstract RuleMatch[] match(AnalyzedSentence sourceText,
       AnalyzedSentence targetText) throws IOException;
 
-  @Override
-  public abstract void reset();
+  private List<StringPair> correctExamples;
+  private List<IncorrectBitextExample> incorrectExamples;
+  private Language sourceLanguage;
 
   /**
    * This method makes no sense for bitext, thus it always returns {@code null}.
@@ -103,7 +106,7 @@ public final List<StringPair> getCorrectBitextExamples() {
    */
   public final void setIncorrectBitextExamples(
       final List<IncorrectBitextExample> incorrectExamples) {
-    this.incorrectExamples = incorrectExamples;
+    this.incorrectExamples = Collections.unmodifiableList(incorrectExamples);
   }
 
   /**

languagetool-core/src/main/java/org/languagetool/rules/bitext/IncorrectBitextExample.java

@@ -19,6 +19,7 @@
 package org.languagetool.rules.bitext;
 
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 import org.languagetool.bitext.StringPair;
@@ -35,14 +36,25 @@ public class IncorrectBitextExample {
   private final List<String> corrections;
 
   public IncorrectBitextExample(final StringPair example) {
-    this(example, null);
+    this(example, (List<String>)null);
   }
 
+  /**
+   * @deprecated use {@link #IncorrectBitextExample(org.languagetool.bitext.StringPair, List<String>)} instead (deprecated since 2.9)
+   */
   public IncorrectBitextExample(final StringPair example, final String[] corrections) {
     this.example = example;
-    this.corrections = Arrays.asList(corrections);
+    this.corrections = Collections.unmodifiableList(Arrays.asList(corrections));
   }
-
+
+  /**
+   * @since 2.9
+   */
+  public IncorrectBitextExample(final StringPair example, final List<String> corrections) {
+    this.example = example;
+    this.corrections = Collections.unmodifiableList(corrections);
+  }
+
   /**
    * Return the example that contains the error.
    */

languagetool-core/src/main/java/org/languagetool/rules/patterns/ElementMatcher.java

@@ -34,6 +34,7 @@
 public class ElementMatcher {
 
   private final Element baseElement;
+
   private Element element;
   private List<ElementMatcher> andGroup;
   private boolean[] andGroupCheck;

languagetool-core/src/main/java/org/languagetool/rules/patterns/Match.java

@@ -43,24 +43,21 @@ public enum IncludeRange {
   }
 
   private final String posTag;
-  private boolean postagRegexp;
   private final boolean suppressMisspelled;
   private final String regexReplace;
   private final String posTagReplace;
   private final CaseConversion caseConversionType;
   private final IncludeRange includeSkipped;
 
-  /**
-   * True if this match element formats a statically defined lemma which is
-   * enclosed by the element, e.g., <tt>&lt;match...&gt;word&lt;/match&gt;</tt>.
-   */
+  private boolean postagRegexp;
+
+  // True if this match element formats a statically defined lemma which is
+  // enclosed by the element, e.g., <match...>word</match>:
   private boolean staticLemma;
 
   private String lemma;
 
-  /**
-   * True if this match element is used for formatting POS token.
-   */
+  // True if this match element is used for formatting POS token:
   private final boolean setPos;
 
   private int tokenRef;

languagetool-core/src/main/java/org/languagetool/rules/patterns/XMLRuleHandler.java

@@ -80,6 +80,7 @@ public class XMLRuleHandler extends DefaultHandler {
   protected static final String MATCH = "match";
   protected static final String UNIFICATION = "unification";
   protected static final String RULE = "rule";
+  protected static final String RULES = "rules";
   protected static final String RULEGROUP = "rulegroup";
   protected static final String NO = "no";
   protected static final String PHRASES = "phrases";

languagetool-core/src/main/java/org/languagetool/rules/patterns/bitext/BitextPatternRuleLoader.java

@@ -65,6 +65,11 @@ public final List<BitextPatternRule> getRules(final InputStream is,
 
 class BitextPatternRuleHandler extends PatternRuleHandler {
 
+  private static final String SOURCE = "source";
+  private static final String TARGET = "target";
+  private static final String SRC_EXAMPLE = "srcExample";
+  private static final String TRG_EXAMPLE = "trgExample";
+
   private PatternRule srcRule;
   private PatternRule trgRule;
 
@@ -89,19 +94,19 @@ List<BitextPatternRule> getBitextRules() {
   public void startElement(final String namespaceURI, final String lName,
       final String qName, final Attributes attrs) throws SAXException {
     switch (qName) {
-      case "rules":
+      case RULES:
         final String languageStr = attrs.getValue("targetLang");
         language = Language.getLanguageForShortName(languageStr);
         break;
-      case "rule":
+      case RULE:
         super.startElement(namespaceURI, lName, qName, attrs);
         correctExamples = new ArrayList<>();
         incorrectExamples = new ArrayList<>();
         break;
-      case "target":
+      case TARGET:
         startPattern(attrs);
         break;
-      case "source":
+      case SOURCE:
         srcLang = Language.getLanguageForShortName(attrs.getValue("lang"));
         break;
       default:
@@ -114,7 +119,7 @@ public void startElement(final String namespaceURI, final String lName,
   public void endElement(final String namespaceURI, final String sName,
       final String qName) throws SAXException {
     switch (qName) {
-      case "rule":
+      case RULE:
         trgRule.setMessage(message.toString());
         if (suggestionMatches != null) {
           for (final Match m : suggestionMatches) {
@@ -130,19 +135,19 @@ public void endElement(final String namespaceURI, final String sName,
         bRule.setSourceLang(srcLang);
         rules.add(bRule);
         break;
-      case "trgExample":
-        trgExample = setExample();
-        break;
-      case "srcExample":
+      case SRC_EXAMPLE:
         srcExample = setExample();
         break;
-      case "source":
+      case TRG_EXAMPLE:
+        trgExample = setExample();
+        break;
+      case SOURCE:
         srcRule = finalizeRule();
         break;
-      case "target":
+      case TARGET:
         trgRule = finalizeRule();
         break;
-      case "example":
+      case EXAMPLE:
         if (inCorrectExample) {
           correctExamples.add(new StringPair(srcExample.getExample(), trgExample.getExample()));
         } else if (inIncorrectExample) {
@@ -151,8 +156,7 @@ public void endElement(final String namespaceURI, final String sName,
             incorrectExamples.add(new IncorrectBitextExample(examplePair));
           } else {
             final List<String> corrections = trgExample.getCorrections();
-            final String[] correctionArray = corrections.toArray(new String[corrections.size()]);
-            incorrectExamples.add(new IncorrectBitextExample(examplePair, correctionArray));
+            incorrectExamples.add(new IncorrectBitextExample(examplePair, corrections));
           }
         }
         inCorrectExample = false;

languagetool-core/src/main/java/org/languagetool/rules/patterns/bitext/FalseFriendsAsBitextLoader.java

@@ -23,6 +23,7 @@
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 import javax.xml.parsers.ParserConfigurationException;
 
@@ -53,7 +54,7 @@ public List<BitextPatternRule> getFalseFriendsAsBitext(
     final List<PatternRule> rules2 = ruleLoader.getRules(JLanguageTool
             .getDataBroker().getFromRulesDirAsStream(filename),
             language, motherTongue);
-    final HashMap<String, PatternRule> srcRules = new HashMap<>();
+    final Map<String, PatternRule> srcRules = new HashMap<>();
     for (PatternRule rule : rules1) {
       srcRules.put(rule.getId(), rule);
     }