IDEA-126982 (Add an inspection to flag a nonfinal class that only has private constructors)

2026-09-27 10:03:11 +07:00 · 2014-07-19 20:05:20 +02:00
parent c54ff24290
commit bbb42a45db
6 changed files with 188 additions and 0 deletions
@@ -408,6 +408,10 @@
                     key="class.name.differs.from.file.name.display.name" groupBundle="messages.InspectionsBundle"
                     groupKey="group.names.class.structure" enabledByDefault="false" level="WARNING"
                     implementationClass="com.siyeh.ig.classlayout.ClassNameDiffersFromFileNameInspection"/>
+    <localInspection language="JAVA" shortName="ClassWithOnlyPrivateConstructors" bundle="com.siyeh.InspectionGadgetsBundle"
+                     key="class.with.only.private.constructors.display.name" groupBundle="messages.InspectionsBundle"
+                     groupKey="group.names.class.structure" enabledByDefault="false" level="WARNING"
+                     implementationClass="com.siyeh.ig.classlayout.ClassWithOnlyPrivateConstructorsInspection"/>
    <localInspection language="JAVA" shortName="ConstantDeclaredInAbstractClass" bundle="com.siyeh.InspectionGadgetsBundle"
                     key="constant.declared.in.abstract.class.display.name" groupBundle="messages.InspectionsBundle"
                     groupKey="group.names.class.structure" enabledByDefault="false" level="WARNING"
@@ -2096,3 +2096,5 @@ serializable.local.class.stores.non.serializable.problem.descriptor=Serializable
 serializable.anonymous.class.stores.non.serializable.problem.descriptor=Serializable anonymous class implicitly stores non-Serializable object of type ''{0}''
 assignment.to.lambda.parameter.display.name=Assignment to lambda parameter
 assignment.to.lambda.parameter.problem.descriptor=Assignment to lambda parameter <code>#ref</code> #loc
+class.with.only.private.constructors.display.name=Class with only 'private' constructors should be declared 'final'
+class.with.only.private.constructors.problem.descriptor=Class <code>#ref</code> with only 'private' constructors should be declared 'final'
@@ -0,0 +1,91 @@
+/*
+ * Copyright 2000-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.siyeh.ig.classlayout;
+
+import com.intellij.psi.PsiClass;
+import com.intellij.psi.PsiMethod;
+import com.intellij.psi.PsiModifier;
+import com.siyeh.InspectionGadgetsBundle;
+import com.siyeh.ig.BaseInspection;
+import com.siyeh.ig.BaseInspectionVisitor;
+import org.jetbrains.annotations.Nls;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * @author Bas Leijdekkers
+ */
+public class ClassWithOnlyPrivateConstructorsInspectionBase extends BaseInspection {
+  @Nls
+  @NotNull
+  @Override
+  public String getDisplayName() {
+    return InspectionGadgetsBundle.message("class.with.only.private.constructors.display.name");
+  }
+
+  @NotNull
+  @Override
+  protected String buildErrorString(Object... infos) {
+    return InspectionGadgetsBundle.message("class.with.only.private.constructors.problem.descriptor");
+  }
+
+  @Override
+  public BaseInspectionVisitor buildVisitor() {
+    return new ClassWithOnlyPrivateConstructorsVisitor();
+  }
+
+  private static class ClassWithOnlyPrivateConstructorsVisitor extends BaseInspectionVisitor {
+
+    @Override
+    public void visitClass(PsiClass aClass) {
+      super.visitClass(aClass);
+      final PsiMethod[] constructors = aClass.getConstructors();
+      if (constructors.length == 0) {
+        return;
+      }
+      for (PsiMethod constructor : constructors) {
+        if (constructor.hasModifierProperty(PsiModifier.FINAL)) {
+          return;
+        }
+      }
+      final PsiClass[] innerClasses = aClass.getInnerClasses();
+      for (PsiClass innerClass : innerClasses) {
+        if (isExtendedByInnerClass(innerClass, aClass, new HashSet<PsiClass>())) {
+          return;
+        }
+      }
+      registerClassError(aClass, aClass);
+    }
+
+    private static boolean isExtendedByInnerClass(PsiClass innerClass, PsiClass superClass, Set<PsiClass> visited) {
+      if (!visited.add(innerClass)) {
+        return false;
+      }
+      if (innerClass.isInheritor(superClass, false)) {
+        return true;
+      }
+      final PsiClass[] innerClasses = innerClass.getInnerClasses();
+      for (PsiClass aClass : innerClasses) {
+        if (isExtendedByInnerClass(aClass, superClass, visited)) {
+          return true;
+        }
+      }
+      return false;
+    }
+  }
+}
@@ -0,0 +1,33 @@
+/*
+ * Copyright 2000-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.siyeh.ig.classlayout;
+
+import com.intellij.psi.PsiClass;
+import com.siyeh.ig.InspectionGadgetsFix;
+import com.siyeh.ig.fixes.MakeClassFinalFix;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * @author Bas Leijdekkers
+ */
+public class ClassWithOnlyPrivateConstructorsInspection extends ClassWithOnlyPrivateConstructorsInspectionBase {
+
+  @Nullable
+  @Override
+  protected InspectionGadgetsFix buildFix(Object... infos) {
+    return new MakeClassFinalFix((PsiClass)infos[0]);
+  }
+}
@@ -0,0 +1,9 @@
+<html>
+<body>
+Reports classes with only <b>private</b> constructors that are not extended by any nested class.
+Such classes can not be extended and should be declared <b>final</b>.
+<!-- tooltip end -->
+<p>
+<small>New in 14</small>
+</body>
+</html>
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2000-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.siyeh.ig.classlayout;
+
+import com.intellij.codeInspection.InspectionProfileEntry;
+import com.siyeh.ig.LightInspectionTestCase;
+import org.jetbrains.annotations.Nullable;
+
+public class ClassWithOnlyPrivateConstructorsInspectionTest extends LightInspectionTestCase {
+
+  public void testSimple() {
+    doTest("class /*Class 'X' with only 'private' constructors should be declared 'final'*/X/**/ {" +
+           "  private X() {}" +
+           "  private X(int i) {}" +
+           "}");
+  }
+
+  public void testExtendingInnerClass() {
+    doTest("class X {\n" +
+           "  private X() {}\n" +
+           "  class Y {\n" +
+           "    class Z extends X{}\n" +
+           "  }\n" +
+           "}");
+  }
+
+  public void testNoConstructors() {
+    doTest("class X {}");
+  }
+
+  @Nullable
+  @Override
+  protected InspectionProfileEntry getInspection() {
+    return new ClassWithOnlyPrivateConstructorsInspection();
+  }
+}