Fix on switch on enum

Author: tomasz-tylenda-sonarsource

java-checks-test-sources/default/src/test/java/checks/tests/SwitchAtLeastThreeCasesCheckSample.java

@@ -79,4 +79,42 @@ public void f(int variable) {
       doSomethingElse();
     }
   }
+
+  public enum SmallEnum {
+    ONE,
+    TWO
+  }
+
+  public void switchOverSmallEnum1(SmallEnum smallEnum) {
+    switch (smallEnum) {
+      case ONE -> {
+        System.out.println("1");
+      }
+      case TWO -> {
+        System.out.println("2");
+      }
+    };
+  }
+
+  public int switchOverSmallEnum2(SmallEnum smallEnum) {
+    int ret = -1;
+    switch (smallEnum) {
+      case ONE:
+        ret = 1;
+        break;
+      case TWO:
+        ret = 2;
+        break;
+    };
+    return ret;
+  }
+
+  public int decoy(int x) {
+    switch(x) { // Noncompliant {{Replace this "switch" statement by "if" statements to increase readability.}}
+      case 0:
+          return 1;
+      default:
+        throw new IllegalStateException("Unexpected value: " + x);
+    }
+  }
 }

java-checks/src/main/java/org/sonar/java/checks/SwitchAtLeastThreeCasesCheck.java

@@ -18,6 +18,7 @@
 
 import org.sonar.check.Rule;
 import org.sonar.plugins.java.api.IssuableSubscriptionVisitor;
+import org.sonar.plugins.java.api.semantic.Symbol;
 import org.sonar.plugins.java.api.tree.CaseGroupTree;
 import org.sonar.plugins.java.api.tree.CaseLabelTree;
 import org.sonar.plugins.java.api.tree.SwitchStatementTree;
@@ -46,7 +47,10 @@ public void visitNode(Tree tree) {
       count += totalLabelCount(caseGroup);
     }
     if (count < 3) {
-      reportIssue(switchStatementTree.switchKeyword(), "Replace this \"switch\" statement by \"if\" statements to increase readability.");
+      Symbol.TypeSymbol typeSymbol = switchStatementTree.expression().symbolType().symbol();
+      if (!typeSymbol.isUnknown() && !typeSymbol.isEnum()) {
+        reportIssue(switchStatementTree.switchKeyword(), "Replace this \"switch\" statement by \"if\" statements to increase readability.");
+      }
     }
   }