1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2026 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.coding;
21
22 import com.puppycrawl.tools.checkstyle.StatelessCheck;
23 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
24 import com.puppycrawl.tools.checkstyle.api.DetailAST;
25 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
26
27 /**
28 * <div>
29 * Checks that classes (except abstract ones) define a constructor and don't rely
30 * on the default one.
31 * </div>
32 *
33 * <p>
34 * Compatibility note: <b>when creating</b> an explicit constructor already
35 * in existing class that used by other in codebases that you do not own, it must match
36 * precisely the declaration of the automatically generated constructor;
37 * even if the constructor should logically be protected, it must be made
38 * public to match the declaration of the automatically generated
39 * constructor, for <b>compatibility</b>.
40 * </p>
41 *
42 * <p>
43 * See
44 * <a href="https://www.oracle.com/technical-resources/articles/java/javadoc-tool.html#defaultconstructors">
45 * Documentation Comments Style Guide</a>.
46 * </p>
47 *
48 * @since 3.4
49 */
50 @StatelessCheck
51 public class MissingCtorCheck extends AbstractCheck {
52
53 /**
54 * A key is pointing to the warning message text in "messages.properties"
55 * file.
56 */
57 public static final String MSG_KEY = "missing.ctor";
58
59 /**
60 * Creates a new {@code MissingCtorCheck} instance.
61 */
62 public MissingCtorCheck() {
63 // no code by default
64 }
65
66 @Override
67 public int[] getDefaultTokens() {
68 return getRequiredTokens();
69 }
70
71 @Override
72 public int[] getAcceptableTokens() {
73 return getRequiredTokens();
74 }
75
76 @Override
77 public int[] getRequiredTokens() {
78 return new int[] {TokenTypes.CLASS_DEF};
79 }
80
81 @Override
82 public void visitToken(DetailAST ast) {
83 final DetailAST modifiers = ast.findFirstToken(TokenTypes.MODIFIERS);
84 if (modifiers.findFirstToken(TokenTypes.ABSTRACT) == null
85 && ast.findFirstToken(TokenTypes.OBJBLOCK)
86 .findFirstToken(TokenTypes.CTOR_DEF) == null) {
87 log(ast, MSG_KEY);
88 }
89 }
90
91 }