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 @Override
45 public int[] getDefaultTokens() {
46 return getRequiredTokens();
47 }
48
49 @Override
50 public int[] getAcceptableTokens() {
51 return getRequiredTokens();
52 }
53
54 @Override
55 public int[] getRequiredTokens() {
56 return new int[] {
57 TokenTypes.ENUM_DEF,
58 };
59 }
60
61 @Override
62 public void visitToken(DetailAST ast) {
63 final DetailAST enumBlock = ast.findFirstToken(TokenTypes.OBJBLOCK);
64 final boolean hasMembers = hasMembersAfterConstants(enumBlock);
65 DetailAST sibling = enumBlock.getFirstChild();
66 while (sibling != null) {
67 if (sibling.getType() == TokenTypes.SEMI
68 && (!hasMembers || isPrecededBySemi(sibling))) {
69 log(sibling, MSG_SEMI);
70 }
71 sibling = sibling.getNextSibling();
72 }
73 }
74
75 /**
76 * Checks if enum body contains any member (method, constructor, field, etc.)
77 * in addition to enum constants and semicolons.
78 *
79 * @param enumBlock the enum body to check
80 * @return true if enum body has members, false if it only has constants and semicolons.
81 */
82 private static boolean hasMembersAfterConstants(DetailAST enumBlock) {
83 boolean result = false;
84 DetailAST sibling = enumBlock.getFirstChild();
85 while (sibling != null) {
86 final int type = sibling.getType();
87 if (type != TokenTypes.LCURLY
88 && type != TokenTypes.RCURLY
89 && type != TokenTypes.ENUM_CONSTANT_DEF
90 && type != TokenTypes.SEMI
91 && type != TokenTypes.COMMA) {
92 result = true;
93 break;
94 }
95 sibling = sibling.getNextSibling();
96 }
97 return result;
98 }
99
100 /**
101 * Checks if semicolon is immediately preceded by another semicolon,
102 * making it a redundant duplicate.
103 *
104 * @param ast semicolon to check
105 * @return true if previous sibling is also a semicolon, false otherwise.
106 */
107 private static boolean isPrecededBySemi(DetailAST ast) {
108 final DetailAST prev = ast.getPreviousSibling();
109 return prev.getType() == TokenTypes.SEMI;
110 }
111 }