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 array initialization do not contain a trailing comma.
30 * Rationale: JLS allows trailing commas in arrays and enumerations, but does not allow
31 * them in other locations. To unify the coding style, the use of trailing commas should
32 * be prohibited.
33 * </div>
34 * {@snippet lang="text" :
35 * int[] foo = new int[] {
36 * 1,
37 * 2
38 * };
39 * }
40 *
41 * <p>
42 * The check demands that there should not be any comma after the last element of an array.
43 * </p>
44 * {@snippet lang="text" :
45 * String[] foo = new String[] {
46 * "FOO",
47 * "BAR", // violation
48 * }
49 * }
50 *
51 * @since 8.28
52 */
53 @StatelessCheck
54 public class NoArrayTrailingCommaCheck extends AbstractCheck {
55
56 /**
57 * A key is pointing to the warning message text in "messages.properties"
58 * file.
59 */
60 public static final String MSG_KEY = "no.array.trailing.comma";
61
62 /**
63 * Creates a new {@code NoArrayTrailingCommaCheck} instance.
64 */
65 public NoArrayTrailingCommaCheck() {
66 // no code by default
67 }
68
69 @Override
70 public int[] getDefaultTokens() {
71 return getRequiredTokens();
72 }
73
74 @Override
75 public int[] getAcceptableTokens() {
76 return getRequiredTokens();
77 }
78
79 @Override
80 public int[] getRequiredTokens() {
81 return new int[] {TokenTypes.ARRAY_INIT};
82 }
83
84 @Override
85 public void visitToken(DetailAST arrayInit) {
86 final DetailAST rcurly = arrayInit.findFirstToken(TokenTypes.RCURLY);
87 final DetailAST previousSibling = rcurly.getPreviousSibling();
88 if (previousSibling != null && previousSibling.getType() == TokenTypes.COMMA) {
89 log(previousSibling, MSG_KEY);
90 }
91 }
92
93 }