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1   ///////////////////////////////////////////////////////////////////////////////////////////////
2   // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3   // Copyright (C) 2001-2025 the original author or authors.
4   //
5   // This library is free software; you can redistribute it and/or
6   // modify it under the terms of the GNU Lesser General Public
7   // License as published by the Free Software Foundation; either
8   // version 2.1 of the License, or (at your option) any later version.
9   //
10  // This library is distributed in the hope that it will be useful,
11  // but WITHOUT ANY WARRANTY; without even the implied warranty of
12  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13  // Lesser General Public License for more details.
14  //
15  // You should have received a copy of the GNU Lesser General Public
16  // License along with this library; if not, write to the Free Software
17  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18  ///////////////////////////////////////////////////////////////////////////////////////////////
19  
20  package com.puppycrawl.tools.checkstyle.checks.metrics;
21  
22  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
23  
24  /**
25   * <div>
26   * Measures the number of distinct classes that are instantiated
27   * within the given class or record. This type of coupling is not caused by inheritance or
28   * the object-oriented paradigm. Generally speaking, any data type with other
29   * data types as members or local variable that is an instantiation (object)
30   * of another class has data abstraction coupling (DAC). The higher the DAC,
31   * the more complex the structure of the class.
32   * </div>
33   *
34   * <p>
35   * This check processes files in the following way:
36   * </p>
37   * <ol>
38   * <li>
39   * Iterates over the list of tokens (defined below) and counts all mentioned classes.
40   * <ul>
41   * <li>
42   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#IMPORT">
43   * PACKAGE_DEF</a>
44   * </li>
45   * <li>
46   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#IMPORT">
47   * IMPORT</a>
48   * </li>
49   * <li>
50   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#CLASS_DEF">
51   * CLASS_DEF</a>
52   * </li>
53   * <li>
54   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#INTERFACE_DEF">
55   * INTERFACE_DEF</a>
56   * </li>
57   * <li>
58   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ENUM_DEF">
59   * ENUM_DEF</a>
60   * </li>
61   * <li>
62   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#LITERAL_NEW">
63   * LITERAL_NEW</a>
64   * </li>
65   * <li>
66   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#RECORD_DEF">
67   * RECORD_DEF</a>
68   * </li>
69   * </ul>
70   * </li>
71   * <li>
72   * If a class was imported with direct import (i.e. {@code import java.math.BigDecimal}),
73   * or the class was referenced with the package name (i.e. {@code java.math.BigDecimal value})
74   * and the package was added to the {@code excludedPackages} parameter, the class
75   * does not increase complexity.
76   * </li>
77   * <li>
78   * If a class name was added to the {@code excludedClasses} parameter,
79   * the class does not increase complexity.
80   * </li>
81   * </ol>
82   * <ul>
83   * <li>
84   * Property {@code excludeClassesRegexps} - Specify user-configured regular
85   * expressions to ignore classes.
86   * Type is {@code java.util.regex.Pattern[]}.
87   * Default value is {@code ^$}.
88   * Since version 7.7
89   * </li>
90   * <li>
91   * Property {@code excludedClasses} - Specify user-configured class names to ignore.
92   * Type is {@code java.lang.String[]}.
93   * Default value is {@code ArrayIndexOutOfBoundsException, ArrayList, Boolean, Byte,
94   * Character, Class, Collection, Deprecated, Deque, Double, DoubleStream, EnumSet, Exception,
95   * Float, FunctionalInterface, HashMap, HashSet, IllegalArgumentException, IllegalStateException,
96   * IndexOutOfBoundsException, IntStream, Integer, LinkedHashMap, LinkedHashSet, LinkedList, List,
97   * Long, LongStream, Map, NullPointerException, Object, Optional, OptionalDouble, OptionalInt,
98   * OptionalLong, Override, Queue, RuntimeException, SafeVarargs, SecurityException, Set, Short,
99   * SortedMap, SortedSet, Stream, String, StringBuffer, StringBuilder, SuppressWarnings, Throwable,
100  * TreeMap, TreeSet, UnsupportedOperationException, Void, boolean, byte, char, double,
101  * float, int, long, short, var, void}.
102  * Since version 5.7
103  * </li>
104  * <li>
105  * Property {@code excludedPackages} - Specify user-configured packages to ignore.
106  * Type is {@code java.lang.String[]}.
107  * Default value is {@code ""}.
108  * Since version 7.7
109  * </li>
110  * <li>
111  * Property {@code max} - Specify the maximum threshold allowed.
112  * Type is {@code int}.
113  * Default value is {@code 7}.
114  * </li>
115  * </ul>
116  *
117  * <p>
118  * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
119  * </p>
120  *
121  * <p>
122  * Violation Message Keys:
123  * </p>
124  * <ul>
125  * <li>
126  * {@code classDataAbstractionCoupling}
127  * </li>
128  * </ul>
129  *
130  * @since 3.4
131  *
132  */
133 public final class ClassDataAbstractionCouplingCheck
134     extends AbstractClassCouplingCheck {
135 
136     /**
137      * A key is pointing to the warning message text in "messages.properties"
138      * file.
139      */
140     public static final String MSG_KEY = "classDataAbstractionCoupling";
141 
142     /** Default allowed complexity. */
143     private static final int DEFAULT_MAX = 7;
144 
145     /** Creates bew instance of the check. */
146     public ClassDataAbstractionCouplingCheck() {
147         super(DEFAULT_MAX);
148     }
149 
150     @Override
151     public int[] getRequiredTokens() {
152         return new int[] {
153             TokenTypes.PACKAGE_DEF,
154             TokenTypes.IMPORT,
155             TokenTypes.CLASS_DEF,
156             TokenTypes.INTERFACE_DEF,
157             TokenTypes.ENUM_DEF,
158             TokenTypes.LITERAL_NEW,
159             TokenTypes.RECORD_DEF,
160         };
161     }
162 
163     @Override
164     public int[] getAcceptableTokens() {
165         return getRequiredTokens();
166     }
167 
168     @Override
169     protected String getLogMessageId() {
170         return MSG_KEY;
171     }
172 
173 }