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.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 * <div class="wrapper"><pre class="prettyprint"><code class="language-java">
35 * int[] foo = new int[] {
36 * 1,
37 * 2
38 * };
39 * </code></pre></div>
40 *
41 * <p>
42 * The check demands that there should not be any comma after the last element of an array.
43 * </p>
44 * <div class="wrapper"><pre class="prettyprint"><code class="language-java">
45 * String[] foo = new String[] {
46 * "FOO",
47 * "BAR", // violation
48 * }
49 * </code></pre></div>
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 @Override
63 public int[] getDefaultTokens() {
64 return getRequiredTokens();
65 }
66
67 @Override
68 public int[] getAcceptableTokens() {
69 return getRequiredTokens();
70 }
71
72 @Override
73 public int[] getRequiredTokens() {
74 return new int[] {TokenTypes.ARRAY_INIT};
75 }
76
77 @Override
78 public void visitToken(DetailAST arrayInit) {
79 final DetailAST rcurly = arrayInit.findFirstToken(TokenTypes.RCURLY);
80 final DetailAST previousSibling = rcurly.getPreviousSibling();
81 if (previousSibling != null && previousSibling.getType() == TokenTypes.COMMA) {
82 log(previousSibling, MSG_KEY);
83 }
84 }
85 }