Issue checkstyle#14424: Added option to skip HideUtilityClassConstruc…

…torCheck validation based on list of annotations

src/main/java/com/puppycrawl/tools/checkstyle/checks/design/HideUtilityClassConstructorCheck.java

@@ -19,10 +19,14 @@
 
 package com.puppycrawl.tools.checkstyle.checks.design;
 
+import java.util.Collections;
+import java.util.Set;
+
 import com.puppycrawl.tools.checkstyle.StatelessCheck;
 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
 import com.puppycrawl.tools.checkstyle.api.DetailAST;
 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
+import com.puppycrawl.tools.checkstyle.utils.AnnotationUtil;
 
 /**
  * <div>
@@ -53,6 +57,19 @@
  *   }
  * }
  * </pre>
+ * <ul>
+ * <li>
+ * Property {@code ignoreAnnotatedBy} - Ignore classes annotated
+ * with the specified annotation(s). Annotation names provided in this property
+ * must exactly match the annotation names on the classes. If the target class has annotations
+ * specified with their fully qualified names (including package), the annotations in this
+ * property should also be specified with their fully qualified names. Similarly, if the target
+ * class has annotations specified with their simple names, this property should contain the
+ * annotations with the same simple names.
+ * Type is {@code java.lang.String[]}.
+ * Default value is {@code ""}.
+ * </li>
+ * </ul>
  *
  * <p>
  * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
@@ -78,6 +95,33 @@ public class HideUtilityClassConstructorCheck extends AbstractCheck {
      */
     public static final String MSG_KEY = "hide.utility.class";
 
+    /**
+     * Ignore classes annotated with the specified annotation(s). Annotation names
+     * provided in this property must exactly match the annotation names on the classes.
+     * If the target class has annotations specified with their fully qualified names
+     * (including package), the annotations in this property should also be specified with
+     * their fully qualified names. Similarly, if the target class has annotations specified
+     * with their simple names, this property should contain the annotations with the same
+     * simple names.
+     */
+    private Set<String> ignoreAnnotatedBy = Collections.emptySet();
+
+    /**
+     * Setter to ignore classes annotated with the specified annotation(s). Annotation names
+     * provided in this property must exactly match the annotation names on the classes.
+     * If the target class has annotations specified with their fully qualified names
+     * (including package), the annotations in this property should also be specified with
+     * their fully qualified names. Similarly, if the target class has annotations specified
+     * with their simple names, this property should contain the annotations with the same
+     * simple names.
+     *
+     * @param annotationNames specified annotation(s)
+     * @since 10.20.0
+     */
+    public void setIgnoreAnnotatedBy(String... annotationNames) {
+        ignoreAnnotatedBy = Set.of(annotationNames);
+    }
+
     @Override
     public int[] getDefaultTokens() {
         return getRequiredTokens();
@@ -96,7 +140,7 @@ public int[] getRequiredTokens() {
     @Override
     public void visitToken(DetailAST ast) {
         // abstract class could not have private constructor
-        if (!isAbstract(ast)) {
+        if (!isAbstract(ast) && !shouldIgnoreClass(ast)) {
             final boolean hasStaticModifier = isStatic(ast);
 
             final Details details = new Details(ast);
@@ -146,6 +190,16 @@ private static boolean isStatic(DetailAST ast) {
             .findFirstToken(TokenTypes.LITERAL_STATIC) != null;
     }
 
+    /**
+     * Checks if class is annotated by specific annotation(s) to skip.
+     *
+     * @param ast class to check
+     * @return true if annotated by ignored annotations
+     */
+    private boolean shouldIgnoreClass(DetailAST ast) {
+        return AnnotationUtil.containsAnnotation(ast, ignoreAnnotatedBy);
+    }
+
     /**
      * Details of class that are required for validation.
      */

src/main/resources/com/puppycrawl/tools/checkstyle/meta/checks/design/HideUtilityClassConstructorCheck.xml

@@ -32,6 +32,17 @@
    }
  }
  &lt;/pre&gt;</description>
+         <properties>
+            <property default-value="" name="ignoreAnnotatedBy" type="java.lang.String[]">
+               <description>Ignore classes annotated
+ with the specified annotation(s). Annotation names provided in this property
+ must exactly match the annotation names on the classes. If the target class has annotations
+ specified with their fully qualified names (including package), the annotations in this
+ property should also be specified with their fully qualified names. Similarly, if the target
+ class has annotations specified with their simple names, this property should contain the
+ annotations with the same simple names.</description>
+            </property>
+         </properties>
          <message-keys>
             <message-key key="hide.utility.class"/>
          </message-keys>

src/test/java/com/puppycrawl/tools/checkstyle/checks/design/HideUtilityClassConstructorCheckTest.java

@@ -146,4 +146,26 @@ public void testGetAcceptableTokens() {
             .isEqualTo(expected);
     }
 
+    @Test
+    public void testIgnoreAnnotatedBy() throws Exception {
+        final String[] expected = {
+            "30:1: " + getCheckMessage(MSG_KEY),
+        };
+        verifyWithInlineConfigParser(
+                getPath("InputHideUtilityClassConstructorIgnoreAnnotationBy.java"),
+                expected
+        );
+    }
+
+    @Test
+    public void testIgnoreAnnotatedByFullQualifier() throws Exception {
+        final String[] expected = {
+            "9:1: " + getCheckMessage(MSG_KEY),
+        };
+        verifyWithInlineConfigParser(
+                getPath("InputHideUtilityClassConstructor"
+                        + "IgnoreAnnotationByFullyQualifiedName.java"),
+                expected
+        );
+    }
 }

src/test/resources/com/puppycrawl/tools/checkstyle/checks/design/hideutilityclassconstructor/InputHideUtilityClassConstructorIgnoreAnnotationBy.java

@@ -0,0 +1,46 @@
+/*
+HideUtilityClassConstructor
+ignoreAnnotatedBy = Skip, SkipWithParam, SkipWithAnnotationAsParam
+
+*/
+
+package com.puppycrawl.tools.checkstyle.checks.design.hideutilityclassconstructor;
+
+@Skip
+public class InputHideUtilityClassConstructorIgnoreAnnotationBy {
+  public static void func() {}
+}
+
+@SkipWithParam(name = "tool1")
+class ToolClass1 {
+  public static void func() {}
+}
+
+@SkipWithAnnotationAsParam(skip = @Skip)
+class ToolClass2 {
+  public static void func() {}
+}
+
+@CommonAnnot
+@Skip
+class ToolClass3 {
+  public static void func() {}
+}
+
+@CommonAnnot // violation, should not have a public or default constructor
+class ToolClass4 {
+  public static void func() {}
+}
+
+
+@interface Skip {}
+
+@interface SkipWithParam {
+  String name();
+}
+
+@interface SkipWithAnnotationAsParam {
+  Skip skip();
+}
+
+@interface CommonAnnot {}

src/test/resources/com/puppycrawl/tools/checkstyle/checks/design/hideutilityclassconstructor/InputHideUtilityClassConstructorIgnoreAnnotationByFullyQualifiedName.java

@@ -0,0 +1,19 @@
+/*
+HideUtilityClassConstructor
+ignoreAnnotatedBy = java.lang.Deprecated
+
+*/
+
+package com.puppycrawl.tools.checkstyle.checks.design.hideutilityclassconstructor;
+
+@Deprecated // violation, should not have a public or default constructor
+public class InputHideUtilityClassConstructorIgnoreAnnotationByFullyQualifiedName {
+  public static void func() {}
+}
+
+@java.lang.Deprecated
+class DeprecatedClass {
+  public static void func() {}
+}
+
+@interface Deprecated {}

src/xdocs-examples/java/com/puppycrawl/tools/checkstyle/checks/design/HideUtilityClassConstructorCheckExamplesTest.java

@@ -35,10 +35,20 @@ protected String getPackageLocation() {
     @Test
     public void testExample1() throws Exception {
         final String[] expected = {
-            "12:1: " + getCheckMessage(MSG_KEY),
-            "37:1: " + getCheckMessage(MSG_KEY),
+            "13:1: " + getCheckMessage(MSG_KEY),
+            "39:1: " + getCheckMessage(MSG_KEY),
+            "45:1: " + getCheckMessage(MSG_KEY),
         };
 
         verifyWithInlineConfigParser(getPath("Example1.java"), expected);
     }
+
+    @Test
+    public void testExample2() throws Exception {
+        final String[] expected = {
+            "42:1: " + getCheckMessage(MSG_KEY),
+        };
+
+        verifyWithInlineConfigParser(getPath("Example2.java"), expected);
+    }
 }

src/xdocs-examples/resources/com/puppycrawl/tools/checkstyle/checks/design/hideutilityclassconstructor/Example1.java

@@ -9,7 +9,9 @@
 package com.puppycrawl.tools.checkstyle.checks.design.hideutilityclassconstructor;
 
 // xdoc section -- start
-class Example1 { // violation
+// violation below, 'should not have a public or default constructor'
+@java.lang.Deprecated
+class Example1 {
 
   public Example1() {
   }
@@ -18,24 +20,33 @@ public static void fun() {
   }
 }
 
-class Foo { // OK
+class Foo {
 
   private Foo() {
   }
 
   static int n;
 }
 
-class Bar { // OK
+class Bar {
 
   protected Bar() {
     // prevents calls from subclass
     throw new UnsupportedOperationException();
   }
 }
 
-class UtilityClass { // violation
+@Deprecated // violation, 'should not have a public or default constructor'
+class UtilityClass {
 
   static float f;
 }
+// violation below, 'should not have a public or default constructor'
+@SpringBootApplication
+class Application1 {
+
+  public static void main(String[] args) {
+  }
+}
 // xdoc section -- end
+@interface SpringBootApplication {}

src/xdocs-examples/resources/com/puppycrawl/tools/checkstyle/checks/design/hideutilityclassconstructor/Example2.java

@@ -0,0 +1,54 @@
+/*xml
+<module name="Checker">
+  <module name="TreeWalker">
+    <module name="HideUtilityClassConstructor">
+      <property name="ignoreAnnotatedBy"
+        value="SpringBootApplication, java.lang.Deprecated" />
+    </module>
+   </module>
+</module>
+*/
+
+package com.puppycrawl.tools.checkstyle.checks.design.hideutilityclassconstructor;
+
+// xdoc section -- start
+// ok below, skipped by annotation
+@java.lang.Deprecated
+class Example2 {
+
+  public Example2() {
+  }
+
+  public static void fun() {
+  }
+}
+
+class Foo2 {
+
+  private Foo2() {
+  }
+
+  static int n;
+}
+
+class Bar2 {
+
+  protected Bar2() {
+    // prevents calls from subclass
+    throw new UnsupportedOperationException();
+  }
+}
+
+@Deprecated // violation, 'should not have a public or default constructor'
+class UtilityClass2 {
+
+  static float f;
+}
+// ok below, skipped by annotation
+@SpringBootApplication
+class Application2 {
+
+  public static void main(String[] args) {
+  }
+}
+// xdoc section -- end