Demo on S2326

Author: tomasz-tylenda-sonarsource

java-checks-common/src/main/java/org/sonar/java/checks/helpers/logic/HelperPredicates.java

@@ -0,0 +1,19 @@
+package org.sonar.java.checks.helpers.logic;
+
+import org.sonar.plugins.java.api.semantic.Symbol;
+
+import static org.sonar.java.checks.helpers.logic.Ternary.UNKNOWN;
+
+/**
+ * Demo for {@link Ternary}
+ */
+public class HelperPredicates {
+  private HelperPredicates() {}
+
+  public static Ternary isUsed(Symbol symbol) {
+    if(symbol.isUnknown()) {
+      return UNKNOWN;
+    }
+    return Ternary.of(!symbol.usages().isEmpty());
+  }
+}

java-checks/src/main/java/org/sonar/java/checks/unused/UnusedTypeParameterCheck.java

@@ -20,6 +20,7 @@
 import java.util.List;
 import java.util.Locale;
 import org.sonar.check.Rule;
+import org.sonar.java.checks.helpers.logic.HelperPredicates;
 import org.sonar.plugins.java.api.IssuableSubscriptionVisitor;
 import org.sonar.plugins.java.api.semantic.Symbol;
 import org.sonar.plugins.java.api.tree.ClassTree;
@@ -43,7 +44,7 @@ public void visitNode(Tree tree) {
     TypeParameters typeParameters = tree.is(Tree.Kind.METHOD) ? ((MethodTree) tree).typeParameters() : ((ClassTree) tree).typeParameters();
     for (TypeParameterTree typeParameter : typeParameters) {
       Symbol symbol = typeParameter.symbol();
-      if (!symbol.isUnknown() && symbol.usages().isEmpty()) {
+      if(HelperPredicates.isUsed(symbol).isFalse()) {
         String message = String.format(ISSUE_MESSAGE, symbol.name(), tree.kind().name().toLowerCase(Locale.ROOT));
         reportIssue(typeParameter.identifier(), message);
       }