Add error prone support and perform code cleanups

.mvn/jvm.config

@@ -0,0 +1,10 @@
+--add-exports jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
+--add-opens jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED
+--add-opens jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED

pom.xml

@@ -110,6 +110,7 @@
         <checker-qual.version>3.52.1</checker-qual.version>
         <commons-lang.version>3.20.0</commons-lang.version>
         <gson.version>2.13.2</gson.version>
+        <error-prone.version>2.45.0</error-prone.version>
         <guava.version>33.5.0-jre</guava.version>
         <jakarta-xml.version>4.0.4</jakarta-xml.version>
         <jaxb-runtime.version>4.0.6</jaxb-runtime.version>
@@ -250,8 +251,18 @@
                 <configuration>
                     <showWarnings>true</showWarnings>
                     <compilerArgs>
-                         <arg>-Xlint:deprecation</arg>
+                        <arg>-Xlint:deprecation</arg>
+                        <arg>-XDcompilePolicy=simple</arg>
+                        <arg>--should-stop=ifError=FLOW</arg>
+                        <arg>-Xplugin:ErrorProne -Xep:ObjectToString:OFF -Xep:BadInstanceof:OFF -Xep:UnusedVariable:OFF -Xep:EqualsGetClass:OFF -Xep:BigDecimalEquals:OFF -Xep:ReferenceEquality:OFF -Xep:ArrayAsKeyOfSetOrMap:OFF -Xep:IterableAndIterator:OFF -Xep:ObjectsHashCodePrimitive:OFF -Xep:StatementSwitchToExpressionSwitch:OFF -Xep:JdkObsolete:OFF -Xep:AddressSelection:OFF -Xep:EmptyBlockTag:OFF -Xep:MissingSummary:OFF -Xep:NonApiType:OFF -Xep:StringSplitter:OFF -Xep:WaitNotInLoop:OFF -Xep:StringConcatToTextBlock:OFF</arg>
                     </compilerArgs>
+                    <annotationProcessorPaths>
+                        <path>
+                            <groupId>com.google.errorprone</groupId>
+                            <artifactId>error_prone_core</artifactId>
+                            <version>${error-prone.version}</version>
+                        </path>
+                    </annotationProcessorPaths>
                 </configuration>
             </plugin>
 

src/main/java/de/learnlib/ralib/automata/util/RAToDot.java

@@ -77,7 +77,7 @@ private void printLocations(RegisterAutomaton ra) {
             if (!acceptingOnly || loc.isAccepting()) {
                 printLocation(loc);
                 stringRA.append(" [shape=");
-                stringRA.append( (loc.isAccepting()) ? "doublecircle" : "circle");
+                stringRA.append(loc.isAccepting() ? "doublecircle" : "circle");
                 stringRA.append("]");
                 stringRA.append(NEWLINE);
             }
@@ -106,8 +106,8 @@ private void printTransitions(RegisterAutomaton ra) {
                 printLocation(t.getDestination());
                 stringRA.append(" [label=<");
 
-                if (t instanceof OutputTransition) {
-                    printOutputLabel( (OutputTransition)t );
+                if (t instanceof OutputTransition outputTransition) {
+                    printOutputLabel( outputTransition );
                 } else {
                     printInputLabel( t );
                 }

src/main/java/de/learnlib/ralib/automata/xml/RegisterAutomatonExporter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2015 The LearnLib Contributors
+ * Copyright (C) 2014-2025 The LearnLib Contributors
  * This file is part of LearnLib, http://www.learnlib.de/.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -87,11 +87,11 @@ private static RegisterAutomaton.Alphabet.Inputs exportInputs(Collection<InputSy
         for (InputSymbol input : is) {
             RegisterAutomaton.Alphabet.Inputs.Symbol s = factory.createRegisterAutomatonAlphabetInputsSymbol();
             s.setName(input.getName());
-            int idx=1;
+            int idx = 1;
             for (DataType t : input.getPtypes()) {
                 RegisterAutomaton.Alphabet.Inputs.Symbol.Param param =
                         factory.createRegisterAutomatonAlphabetInputsSymbolParam();
-                param.setName("p" + (idx++));
+                param.setName("p" + idx++);
                 param.setType(t.getName());
                 s.getParam().add(param);
             }
@@ -105,11 +105,11 @@ private static RegisterAutomaton.Alphabet.Outputs exportOutputs(Collection<Outpu
         for (OutputSymbol output : os) {
             RegisterAutomaton.Alphabet.Outputs.Symbol s = factory.createRegisterAutomatonAlphabetOutputsSymbol();
             s.setName(output.getName());
-            int idx=1;
+            int idx = 1;
             for (DataType t : output.getPtypes()) {
                 RegisterAutomaton.Alphabet.Outputs.Symbol.Param param =
                         factory.createRegisterAutomatonAlphabetOutputsSymbolParam();
-                param.setName("p" + (idx++));
+                param.setName("p" + idx++);
                 param.setType(t.getName());
                 s.getParam().add(param);
             }
@@ -130,7 +130,7 @@ private static RegisterAutomaton.Locations exportLocations(
             if (ra.getInitialState().equals(loc)) {
                 l.setInitial("true");
             }
-            ret.getLocation()   .add(l);
+            ret.getLocation().add(l);
         }
         return ret;
     }
@@ -140,11 +140,11 @@ private static RegisterAutomaton.Transitions exportTransitions(Collection<Transi
                 factory.createRegisterAutomatonTransitions();
 
         for (Transition t : trans) {
-            if (t instanceof OutputTransition) {
-                ret.getTransition().add( exportOutputTransition( (OutputTransition)t, tmp ));
+            if (t instanceof OutputTransition outputTransition) {
+                ret.getTransition().add( exportOutputTransition(outputTransition, tmp));
             }
             else {
-                ret.getTransition().add( exportInputTransition( t ));
+                ret.getTransition().add(exportInputTransition(t));
             }
         }
         return ret;
@@ -272,10 +272,9 @@ public static void write(de.learnlib.ralib.automata.RegisterAutomaton ra, Consta
         Set<OutputSymbol> outputs = new HashSet<>();
         for (Transition t : ra.getTransitions()) {
             ParameterizedSymbol ps = t.getLabel();
-            if (ps instanceof InputSymbol) {
-                inputs.add((InputSymbol)ps);
-            }
-            else {
+            if (ps instanceof InputSymbol inputSymbol) {
+                inputs.add(inputSymbol);
+            } else {
                 outputs.add((OutputSymbol) ps);
             }
         }

src/main/java/de/learnlib/ralib/automata/xml/RegisterAutomatonImporter.java

@@ -185,7 +185,7 @@ else if (constMap.containsKey(ass.value)) {
             Assignment assign = new Assignment(assignments);
 
             // output
-            if (ps instanceof OutputSymbol) {
+            if (ps instanceof OutputSymbol outputSymbol) {
 
                 Parameter[] pList = paramList(ps);
                 int idx = 0;
@@ -223,7 +223,7 @@ else if (constMap.containsKey(ass.value)) {
                 OutputMapping outMap = new OutputMapping(fresh, outputs);
 
                 OutputTransition tOut = new OutputTransition(p, outMap,
-                        (OutputSymbol) ps, from, to, assign);
+                        outputSymbol, from, to, assign);
                 iora.addTransition(from, ps, tOut);
                 LOGGER.trace(Category.EVENT, "Loading: {}", tOut);
             } // input
@@ -321,10 +321,6 @@ private DataType getOrCreateType(String name) {
         return t;
     }
 
-    private boolean isDoubleTempCheck(String name) {
-        return name.equals("DOUBLE") || name.equals("double");
-    }
-
     private Map<String, SymbolicDataValue> buildValueMap(
             Map<String, ? extends SymbolicDataValue> ... maps) {
         Map<String, SymbolicDataValue> ret = new LinkedHashMap<>();

src/main/java/de/learnlib/ralib/data/Bijection.java

@@ -123,6 +123,7 @@ public Mapping<T, T> toVarMapping() {
 		return vars;
 	}
 
+	@Override
 	public String toString() {
 		return injection.toString();
 	}

src/main/java/de/learnlib/ralib/dt/DT.java

@@ -166,8 +166,8 @@ private DTLeaf sift(MappedPrefix mp, DTInnerNode from, boolean add) {
         } while (leaf == null);
 
         if (add && !leaf.getAccessSequence().equals(mp.getPrefix())) {
-            if (mp instanceof ShortPrefix) {
-                leaf.addShortPrefix((ShortPrefix) mp);
+            if (mp instanceof ShortPrefix shortPrefix) {
+                leaf.addShortPrefix(shortPrefix);
             } else {
                 leaf.addPrefix(mp);
             }
@@ -201,7 +201,7 @@ public void split(Word<PSymbolInstance> prefix, SymbolicSuffix suffix, DTLeaf le
 
         // update old leaf
         boolean removed = leaf.removeShortPrefix(prefix);
-        assert (removed); // must not split a prefix that isn't there
+        assert removed; // must not split a prefix that isn't there
 
         //SDT tqr2 = leaf.getPrimePrefix().computeTQR(suffix, oracle);
         PathResult r2 = PathResult.computePathResult(oracle, leaf.getPrimePrefix(), node.getSuffixes(), ioMode);

src/main/java/de/learnlib/ralib/equivalence/IOCounterexampleLoopRemover.java

@@ -60,7 +60,7 @@ private static class Loop {
         private final int min;
         private final int max;
 
-        public Loop(int min, int max) {
+        Loop(int min, int max) {
             this.min = min;
             this.max = max;
         }

src/main/java/de/learnlib/ralib/equivalence/IOEquivalenceTest.java

@@ -57,16 +57,16 @@ private static class Pair<T1, T2> {
         private final T1 first;
         private final T2 second;
 
-        public Pair(T1 first, T2 second) {
+        Pair(T1 first, T2 second) {
             this.first = first;
             this.second = second;
         }
 
-        public T1 getFirst() {
+        T1 getFirst() {
             return first;
         }
 
-        public T2 getSecond() {
+        T2 getSecond() {
             return second;
         }
     }
@@ -83,7 +83,7 @@ private static class Tuple {
         RegisterValuation sys1reg;
         RegisterValuation sys2reg;
 
-        public Tuple(RALocation l1, RALocation l2, RegisterValuation r1, RegisterValuation r2) {
+        Tuple(RALocation l1, RALocation l2, RegisterValuation r1, RegisterValuation r2) {
             sys1loc = l1;
             sys2loc = l2;
             sys1reg = RegisterValuation.copyOf(r1);
@@ -179,7 +179,7 @@ private static class Triple {
         Word<PSymbolInstance> as;
         Word<PSymbolInstance> trace;
 
-        public Triple(RALocation l1, RALocation l2, RegisterValuation r1, RegisterValuation r2, Word<PSymbolInstance> w, Word<PSymbolInstance> t) {
+        Triple(RALocation l1, RALocation l2, RegisterValuation r1, RegisterValuation r2, Word<PSymbolInstance> w, Word<PSymbolInstance> t) {
             sys1loc = l1;
             sys2loc = l2;
             sys1reg = RegisterValuation.copyOf(r1);

src/main/java/de/learnlib/ralib/equivalence/RAEquivalenceTest.java

@@ -53,7 +53,7 @@ private static class Tuple {
         RegisterValuation sys1reg;
         RegisterValuation sys2reg;
 
-        public Tuple(RALocation l1, RALocation l2, RegisterValuation r1, RegisterValuation r2) {
+        Tuple(RALocation l1, RALocation l2, RegisterValuation r1, RegisterValuation r2) {
             sys1loc = l1;
             sys2loc = l2;
             sys1reg = RegisterValuation.copyOf(r1);
@@ -153,7 +153,7 @@ private static class Triple {
         Word<PSymbolInstance> as;
         Word<PSymbolInstance> trace;
 
-        public Triple(RALocation l1, RALocation l2, RegisterValuation r1, RegisterValuation r2, Word w, Word t) {
+        Triple(RALocation l1, RALocation l2, RegisterValuation r1, RegisterValuation r2, Word w, Word t) {
             sys1loc = l1;
             sys2loc = l2;
             sys1reg = RegisterValuation.copyOf(r1);

src/main/java/de/learnlib/ralib/learning/IOAutomatonBuilder.java

@@ -83,7 +83,7 @@ protected Transition createTransition(ParameterizedSymbol action,
             return null;
         }
 
-        if (!(action instanceof OutputSymbol)) {
+        if (!(action instanceof OutputSymbol outputSymbol)) {
             return super.createTransition(action, guard, src_loc, dest_loc, assign);
         }
 
@@ -105,7 +105,7 @@ protected Transition createTransition(ParameterizedSymbol action,
         OutputMapping outMap = new OutputMapping(fresh, outmap);
 
         return new OutputTransition(ExpressionUtil.TRUE,
-                outMap, (OutputSymbol) action, src_loc, dest_loc, assign);
+                outMap, outputSymbol, src_loc, dest_loc, assign);
     }
 
     private void analyzeExpression(Expression<Boolean> expr,
@@ -125,12 +125,12 @@ else if (expr instanceof NumericBooleanExpression nbe) {
                 Parameter p = null;
                 SymbolicDataValue sv = null;
 
-                if (left instanceof Parameter) {
+                if (left instanceof Parameter parameter) {
                     if (right instanceof Parameter) {
                         throw new UnsupportedOperationException("not implemented yet.");
                     }
                     else {
-                        p = (Parameter) left;
+                        p = parameter;
                         sv = (SymbolicDataValue) right;
                     }
                 }

src/main/java/de/learnlib/ralib/learning/QueryStatistics.java

@@ -16,7 +16,7 @@ public class QueryStatistics {
 	public static final int CE_ANALYSIS = 2;
 	public static final int CE_PROCESSING = 3;
 	public static final int OTHER = 4;
-	public static final String[] PHASES = {"Testing", "CE Optimization", "CE Analysis", "Processing / Refinement", "Other"};
+	private static final String[] PHASES = {"Testing", "CE Optimization", "CE Analysis", "Processing / Refinement", "Other"};
 	private static final int MEASUREMENTS = 5;
 
 	private final QueryCounter queryCounter;

src/main/java/de/learnlib/ralib/learning/SymbolicSuffix.java

@@ -202,7 +202,7 @@ public SymbolicSuffix(Word<ParameterizedSymbol> actions, Map<Integer, SuffixValu
     			seen.add(sv);
     		} else if (seen.contains(sv)) {
     			int id = dataValues.entrySet()
-   			         .stream().filter((a) -> (a.getValue().equals(sv)))
+			         .stream().filter((a) -> a.getValue().equals(sv))
    			         .sorted(Map.Entry.comparingByKey(Comparator.naturalOrder()))
    			         .findFirst()
    			         .get()

src/main/java/de/learnlib/ralib/oracles/mto/MultiTheoryBranching.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2015 The LearnLib Contributors
+ * Copyright (C) 2014-2025 The LearnLib Contributors
  * This file is part of LearnLib, http://www.learnlib.de/.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -88,7 +88,7 @@ void toString(StringBuilder sb, String indentation) {
 
         protected Map<SuffixValue, Set<DataValue>> collectDVs() {
             Map<SuffixValue, Set<DataValue>> dvs = new LinkedHashMap();
-            if (!(this.next.keySet()).isEmpty()) {
+            if (! this.next.keySet().isEmpty()) {
                 dvs.put(this.parameter, this.next.keySet());
                 for (Map.Entry<DataValue, Node> e : this.next.entrySet()) {
                     dvs.putAll(e.getValue().collectDVs());
@@ -99,7 +99,7 @@ protected Map<SuffixValue, Set<DataValue>> collectDVs() {
 
         protected Map<SuffixValue, Set<SDTGuard>> collectGuards() {
             Map<SuffixValue, Set<SDTGuard>> guards = new LinkedHashMap();
-            if (!(this.next.keySet()).isEmpty()) {
+            if (! this.next.keySet().isEmpty()) {
                 guards.put(this.parameter, new LinkedHashSet<SDTGuard>(this.guards.values()));
                 for (Map.Entry<DataValue, Node> e : this.next.entrySet()) {
                     guards.putAll(e.getValue().collectGuards());
@@ -109,7 +109,7 @@ protected Map<SuffixValue, Set<SDTGuard>> collectGuards() {
         }
 
         protected SDT buildFakeSDT() {
-            if (!(this.next.keySet()).isEmpty()) {
+            if (! this.next.keySet().isEmpty()) {
                 Map<SDTGuard, SDT> map = new LinkedHashMap();
                 for (Map.Entry<DataValue, Node> e : this.next.entrySet()) {
                     SDTGuard guard = guards.get(e.getKey());

src/main/java/de/learnlib/ralib/oracles/mto/MultiTheoryTreeOracle.java

@@ -173,12 +173,6 @@ private Node createFreshNode(int i, Word<PSymbolInstance> prefix, ParameterizedS
         }
     }
 
-    private Node createNode(int i, Word<PSymbolInstance> prefix, ParameterizedSymbol ps, SuffixValuation pval,
-            SDT... sdts) {
-        Node n = createNode(i, prefix, ps, pval, new LinkedHashMap<>(), sdts);
-        return n;
-    }
-
     private Node createNode(int i, Word<PSymbolInstance> prefix, ParameterizedSymbol ps, SuffixValuation pval,
             Map<SuffixValue, Set<DataValue>> oldDvMap, SDT... sdts) {
 
@@ -324,15 +318,15 @@ public SDTGuard conjoin(SDTGuard guard1, SDTGuard guard2) {
             return guard1;
         }
 
-        if (guard1 instanceof SDTGuard.SDTAndGuard && guard2 instanceof SDTGuard.SDTAndGuard) {
-            List<SDTGuard> guards = new ArrayList<SDTGuard>(((SDTGuard.SDTAndGuard) guard1).conjuncts());
-            guards.addAll(((SDTGuard.SDTAndGuard) guard2).conjuncts());
+        if (guard1 instanceof SDTGuard.SDTAndGuard sdtAndGuard1 && guard2 instanceof SDTGuard.SDTAndGuard sdtAndGuard2) {
+            List<SDTGuard> guards = new ArrayList<SDTGuard>(sdtAndGuard1.conjuncts());
+            guards.addAll(sdtAndGuard2.conjuncts());
             return new SDTGuard.SDTAndGuard(guard1.getParameter(), guards);
         }
 
         if (guard1 instanceof SDTGuard.SDTAndGuard || guard2 instanceof SDTGuard.SDTAndGuard) {
-            SDTGuard.SDTAndGuard andGuard = guard1 instanceof SDTGuard.SDTAndGuard ?
-                    (SDTGuard.SDTAndGuard) guard1 : (SDTGuard.SDTAndGuard) guard2;
+            SDTGuard.SDTAndGuard andGuard = guard1 instanceof SDTGuard.SDTAndGuard sdtAndGuard ?
+                    sdtAndGuard : (SDTGuard.SDTAndGuard) guard2;
             SDTGuard otherGuard = guard2 instanceof SDTGuard.SDTAndGuard ? guard1 : guard2;
             List<SDTGuard> conjuncts = andGuard.conjuncts();
             conjuncts.add(otherGuard);
@@ -459,7 +453,7 @@ public Branching updateBranching(Word<PSymbolInstance> prefix, ParameterizedSymb
         updated[0] = oldBranching.buildFakeSDT();
         System.arraycopy(sdts, 0, updated, 1, sdts.length);
 
-        Node n = createNode(1, prefix, ps, new SuffixValuation(),oldDvs, updated);
+        Node n = createNode(1, prefix, ps, new SuffixValuation(), oldDvs, updated);
         MultiTheoryBranching mtb = new MultiTheoryBranching(prefix, ps, n, constants, updated);
         return mtb;
     }

src/main/java/de/learnlib/ralib/smt/SMTUtil.java

@@ -91,7 +91,7 @@ private static Variable getOrCreate(SymbolicDataValue dv, Map<SymbolicDataValue,
     }
 
     public static Constant toConstant(DataValue v) {
-        return new Constant( BuiltinTypes.DECIMAL, (v.getValue()));
+        return new Constant(BuiltinTypes.DECIMAL, v.getValue());
     }
 
     public static Variable toVariable(DataValue v) {