plugins/InspectionGadgets/src/com/siyeh/ig/psiutils/UtilityClassUtil.java

   1 /*
   2  * Copyright 2003-2008 Dave Griffith, Bas Leijdekkers
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 package com.siyeh.ig.psiutils;
  17
  18 import com.intellij.psi.*;
  19 import org.jetbrains.annotations.NotNull;
  20
  21 public class UtilityClassUtil {
  22     private UtilityClassUtil() {
  23         super();
  24     }
  25
  26     public static boolean isUtilityClass(@NotNull PsiClass aClass) {
  27         if (aClass.isInterface() || aClass.isEnum() || aClass.isAnnotationType()) {
  28             return false;
  29         }
  30         if(aClass instanceof PsiTypeParameter ||
  31                 aClass instanceof PsiAnonymousClass){
  32             return false;
  33         }
  34         final PsiReferenceList extendsList = aClass.getExtendsList();
  35         if (extendsList != null
  36                 && extendsList.getReferenceElements().length > 0) {
  37             return false;
  38         }
  39         final PsiReferenceList implementsList = aClass.getImplementsList();
  40         if (implementsList != null
  41                 && implementsList.getReferenceElements().length > 0) {
  42             return false;
  43         }
  44         final PsiMethod[] methods = aClass.getMethods();
  45         final int staticMethodCount = countStaticMethods(methods);
  46         if (staticMethodCount < 0) {
  47             return false;
  48         }
  49         final PsiField[] fields = aClass.getFields();
  50         if (!allFieldsStatic(fields)) {
  51             return false;
  52         }
  53         return staticMethodCount != 0 || fields.length != 0;
  54     }
  55
  56     private static boolean allFieldsStatic(PsiField[] fields) {
  57         for(final PsiField field : fields){
  58             if(!field.hasModifierProperty(PsiModifier.STATIC)){
  59                 return false;
  60             }
  61         }
  62         return true;
  63     }
  64
  65     /**
  66      * @return -1 if an instance method was found, else the number of static
  67      * methods in the class
  68      */
  69     private static int countStaticMethods(PsiMethod[] methods) {
  70         int staticCount = 0;
  71         for(final PsiMethod method : methods){
  72             if (method.isConstructor()) {
  73                 continue;
  74             }
  75             if (!method.hasModifierProperty(PsiModifier.STATIC)) {
  76                 return -1;
  77             }
  78             if (method.hasModifierProperty(PsiModifier.PRIVATE)) {
  79                 continue;
  80             }
  81             staticCount++;
  82         }
  83         return staticCount;
  84     }
  85 }