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 if unnecessary semicolon is in enum definitions.
30 * Semicolon is not needed if enum body contains only enum constants.
31 * </div>
32 *
33 * @since 8.22
34 */
35 @StatelessCheck
36 public final class UnnecessarySemicolonInEnumerationCheck extends AbstractCheck {
37
38 /**
39 * A key is pointing to the warning message text in "messages.properties"
40 * file.
41 */
42 public static final String MSG_SEMI = "unnecessary.semicolon";
43
44 /**
45 * Creates a new {@code UnnecessarySemicolonInEnumerationCheck} instance.
46 */
47 public UnnecessarySemicolonInEnumerationCheck() {
48 // no code by default
49 }
50
51 @Override
52 public int[] getDefaultTokens() {
53 return getRequiredTokens();
54 }
55
56 @Override
57 public int[] getAcceptableTokens() {
58 return getRequiredTokens();
59 }
60
61 @Override
62 public int[] getRequiredTokens() {
63 return new int[] {
64 TokenTypes.ENUM_DEF,
65 };
66 }
67
68 @Override
69 public void visitToken(DetailAST ast) {
70 final DetailAST enumBlock = ast.findFirstToken(TokenTypes.OBJBLOCK);
71 final boolean hasMembers = hasMembersAfterConstants(enumBlock);
72 DetailAST sibling = enumBlock.getFirstChild();
73 while (sibling != null) {
74 if (sibling.getType() == TokenTypes.SEMI
75 && (!hasMembers || isPrecededBySemi(sibling))) {
76 log(sibling, MSG_SEMI);
77 }
78 sibling = sibling.getNextSibling();
79 }
80 }
81
82 /**
83 * Checks if enum body contains any member (method, constructor, field, etc.)
84 * in addition to enum constants and semicolons.
85 *
86 * @param enumBlock the enum body to check
87 * @return true if enum body has members, false if it only has constants and semicolons.
88 */
89 private static boolean hasMembersAfterConstants(DetailAST enumBlock) {
90 boolean result = false;
91 DetailAST sibling = enumBlock.getFirstChild();
92 while (sibling != null) {
93 final int type = sibling.getType();
94 if (type != TokenTypes.LCURLY
95 && type != TokenTypes.RCURLY
96 && type != TokenTypes.ENUM_CONSTANT_DEF
97 && type != TokenTypes.SEMI
98 && type != TokenTypes.COMMA) {
99 result = true;
100 break;
101 }
102 sibling = sibling.getNextSibling();
103 }
104 return result;
105 }
106
107 /**
108 * Checks if semicolon is immediately preceded by another semicolon,
109 * making it a redundant duplicate.
110 *
111 * @param ast semicolon to check
112 * @return true if previous sibling is also a semicolon, false otherwise.
113 */
114 private static boolean isPrecededBySemi(DetailAST ast) {
115 final DetailAST prev = ast.getPreviousSibling();
116 return prev.getType() == TokenTypes.SEMI;
117 }
118
119 }