consider static and non-static methods when language level is 8.0 or higher

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/classlayout/ClassMayBeInterfaceInspection.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2013 Dave Griffith, Bas Leijdekkers
+ * Copyright 2003-2014 Dave Griffith, Bas Leijdekkers
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,6 +22,7 @@ import com.intellij.psi.*;
 import com.intellij.psi.search.SearchScope;
 import com.intellij.psi.search.searches.ClassInheritorsSearch;
 import com.intellij.psi.util.PsiTreeUtil;
+import com.intellij.psi.util.PsiUtil;
 import com.siyeh.InspectionGadgetsBundle;
 import com.siyeh.ig.BaseInspection;
 import com.siyeh.ig.BaseInspectionVisitor;
@@ -88,6 +89,21 @@ public class ClassMayBeInterfaceInspection extends BaseInspection {
     }
 
     private static void changeClassToInterface(PsiClass aClass) {
+      for (PsiMethod method : aClass.getMethods()) {
+        PsiUtil.setModifierProperty(method, PsiModifier.PUBLIC, false);
+        if (method.hasModifierProperty(PsiModifier.STATIC) || method.hasModifierProperty(PsiModifier.ABSTRACT)) {
+          continue;
+        }
+        PsiUtil.setModifierProperty(method, PsiModifier.DEFAULT, true);
+      }
+      for (PsiField field : aClass.getFields()) {
+        PsiUtil.setModifierProperty(field, PsiModifier.PUBLIC, false);
+        PsiUtil.setModifierProperty(field, PsiModifier.STATIC, false);
+        PsiUtil.setModifierProperty(field, PsiModifier.FINAL, false);
+      }
+      for (PsiClass innerClass : aClass.getInnerClasses()) {
+        PsiUtil.setModifierProperty(innerClass, PsiModifier.PUBLIC, false);
+      }
       final PsiIdentifier nameIdentifier = aClass.getNameIdentifier();
       if (nameIdentifier == null) {
         return;
@@ -99,11 +115,8 @@ public class ClassMayBeInterfaceInspection extends BaseInspection {
       if (classKeyword == null) {
         return;
       }
-      final PsiModifierList modifierList = aClass.getModifierList();
-      if (modifierList != null) {
-        modifierList.setModifierProperty(PsiModifier.ABSTRACT, false);
-        modifierList.setModifierProperty(PsiModifier.FINAL, false);
-      }
+      PsiUtil.setModifierProperty(aClass, PsiModifier.ABSTRACT, false);
+      PsiUtil.setModifierProperty(aClass, PsiModifier.FINAL, false);
       classKeyword.replace(interfaceKeyword);
     }
 
@@ -124,7 +137,7 @@ public class ClassMayBeInterfaceInspection extends BaseInspection {
     }
 
     private static void moveSubClassExtendsToImplements(List<PsiClass> inheritors) {
-      PsiClass oldClass = inheritors.get(0);
+      final PsiClass oldClass = inheritors.get(0);
       final PsiElementFactory elementFactory = JavaPsiFacade.getInstance(oldClass.getProject()).getElementFactory();
       final PsiJavaCodeReferenceElement classReference = elementFactory.createClassReferenceElement(oldClass);
       for (int i = 1; i < inheritors.size(); i++) {
@@ -170,6 +183,9 @@ public class ClassMayBeInterfaceInspection extends BaseInspection {
       if (aClass instanceof PsiTypeParameter || aClass instanceof PsiAnonymousClass) {
         return;
       }
+      if (!aClass.hasModifierProperty(PsiModifier.ABSTRACT)) {
+        return;
+      }
       if (!mayBeInterface(aClass)) {
         return;
       }
@@ -206,7 +222,10 @@ public class ClassMayBeInterfaceInspection extends BaseInspection {
     private static boolean allMethodsPublicAbstract(PsiClass aClass) {
       final PsiMethod[] methods = aClass.getMethods();
       for (final PsiMethod method : methods) {
-        if (!(method.hasModifierProperty(PsiModifier.ABSTRACT) && method.hasModifierProperty(PsiModifier.PUBLIC))) {
+        if (!PsiUtil.isLanguageLevel8OrHigher(aClass) && !method.hasModifierProperty(PsiModifier.ABSTRACT)) {
+          return false;
+        }
+        else if (!method.hasModifierProperty(PsiModifier.PUBLIC) || method.hasModifierProperty(PsiModifier.FINAL)) {
           return false;
         }
       }

plugins/InspectionGadgets/src/inspectionDescriptions/ClassMayBeInterface.html

@@ -1,10 +1,10 @@
 <html>
 <body>
-Reports any concrete or abstract classes
-which may be simplified to be interfaces. This occurs if the class has no superclass (other
+Reports <b>abstract</b> classes which can be converted to interfaces.
+A class may be converted to an interface if it has no superclass (other
 than Object), has no fields declared that are not <b>static</b>, <b>final</b>, and <b>public</b>, and has no
-methods declared that are not <b>public</b> and <b>abstract</b>, and no inner classes
-that cannot themselves be interfaces.
+methods declared that are not <b>public</b> and <b>abstract</b> and no inner classes that are not <b>public</b>.
+When using a language level of 8.0 or higher classes containing static and non-static methods will also be reported.
 <!-- tooltip end -->
 <p>
 

plugins/InspectionGadgets/test/com/siyeh/igfixes/classlayout/class_may_be_interface/ConvertMe.after.java

@@ -0,0 +1,15 @@
+package com.siyeh.igfixes.classlayout.class_may_be_interface;
+
+interface ConvertMe {
+
+  String S = "";
+
+  default void m() {}
+
+  static void n() {
+    new ConvertMe() {};
+    class X implements ConvertMe {}
+  }
+
+  class A {}
+}

plugins/InspectionGadgets/test/com/siyeh/igfixes/classlayout/class_may_be_interface/ConvertMe.java

@@ -0,0 +1,15 @@
+package com.siyeh.igfixes.classlayout.class_may_be_interface;
+
+abstract class <caret>ConvertMe {
+
+  public static final String S = "";
+
+  public void m() {}
+
+  public static void n() {
+    new ConvertMe() {};
+    class X extends ConvertMe {}
+  }
+
+  public class A {}
+}

plugins/InspectionGadgets/testsrc/com/siyeh/ig/classlayout/ClassMayBeInterfaceInspectionTest.java

@@ -0,0 +1,53 @@
+/*
+ * 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;
+
+/**
+ * @author Bas Leijdekkers
+ */
+public class ClassMayBeInterfaceInspectionTest extends LightInspectionTestCase {
+
+  public void testOne() {
+    doTest("abstract class /*'ConvertMe' may be interface*/ConvertMe/**/ {\n" +
+           "    public static final String S = \"\";\n" +
+           "    public void m() {}\n" +
+           "    public static void n() {\n" +
+           "        new ConvertMe() {};\n" +
+           "        class X extends ConvertMe {}\n" +
+           "    }\n" +
+           "    public class A {}\n" +
+           "}");
+  }
+
+  public void testOnTwo() {
+    doTest("class ConvertMe {\n" +
+           "    public static final String S = \"\";\n" +
+           "    public void m() {}\n" +
+           "    public static void n() {\n" +
+           "        new ConvertMe() {};\n" +
+           "        class X extends ConvertMe {}\n" +
+           "    }\n" +
+           "    public class A {}\n" +
+           "}");
+  }
+  @Override
+  protected InspectionProfileEntry getInspection() {
+    return new ClassMayBeInterfaceInspection();
+  }
+}

plugins/InspectionGadgets/testsrc/com/siyeh/ig/fixes/classlayout/ClassMayBeInterfaceFixTest.java

@@ -0,0 +1,37 @@
+/*
+ * 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.fixes.classlayout;
+
+import com.siyeh.InspectionGadgetsBundle;
+import com.siyeh.ig.IGQuickFixesTestCase;
+import com.siyeh.ig.classlayout.ClassMayBeInterfaceInspection;
+
+/**
+ * @author Bas Leijdekkers
+ */
+public class ClassMayBeInterfaceFixTest extends IGQuickFixesTestCase {
+
+  @Override
+  protected void setUp() throws Exception {
+    super.setUp();
+    myFixture.enableInspections(new ClassMayBeInterfaceInspection());
+    myRelativePath = "classlayout/class_may_be_interface";
+    myDefaultHint = InspectionGadgetsBundle.message("class.may.be.interface.convert.quickfix");
+  }
+
+  public void testConvertMe() { doTest(); }
+
+}