001/////////////////////////////////////////////////////////////////////////////////////////////// 002// checkstyle: Checks Java source code and other text files for adherence to a set of rules. 003// Copyright (C) 2001-2024 the original author or authors. 004// 005// This library is free software; you can redistribute it and/or 006// modify it under the terms of the GNU Lesser General Public 007// License as published by the Free Software Foundation; either 008// version 2.1 of the License, or (at your option) any later version. 009// 010// This library is distributed in the hope that it will be useful, 011// but WITHOUT ANY WARRANTY; without even the implied warranty of 012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 013// Lesser General Public License for more details. 014// 015// You should have received a copy of the GNU Lesser General Public 016// License along with this library; if not, write to the Free Software 017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 018/////////////////////////////////////////////////////////////////////////////////////////////// 019 020package com.puppycrawl.tools.checkstyle.checks.coding; 021 022import com.puppycrawl.tools.checkstyle.StatelessCheck; 023import com.puppycrawl.tools.checkstyle.api.AbstractCheck; 024import com.puppycrawl.tools.checkstyle.api.DetailAST; 025import com.puppycrawl.tools.checkstyle.api.TokenTypes; 026import com.puppycrawl.tools.checkstyle.utils.TokenUtil; 027 028/** 029 * <p> 030 * Checks that enum definition does not contain a trailing comma. 031 * Rationale: JLS allows trailing commas in arrays and enumerations, but does not allow 032 * them in other locations. To unify the coding style, the use of trailing commas should 033 * be prohibited. 034 * </p> 035 * <pre> 036 * enum Foo1 { 037 * FOO, 038 * BAR; 039 * } 040 * </pre> 041 * <p> 042 * The check demands that there should not be any comma after last constant in 043 * enum definition. 044 * </p> 045 * <pre> 046 * enum Foo1 { 047 * FOO, 048 * BAR, //violation 049 * } 050 * </pre> 051 * <p> 052 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 053 * </p> 054 * <p> 055 * Violation Message Keys: 056 * </p> 057 * <ul> 058 * <li> 059 * {@code no.enum.trailing.comma} 060 * </li> 061 * </ul> 062 * 063 * @since 8.29 064 */ 065@StatelessCheck 066public class NoEnumTrailingCommaCheck extends AbstractCheck { 067 068 /** 069 * A key is pointing to the warning message text in "messages.properties" 070 * file. 071 */ 072 public static final String MSG_KEY = "no.enum.trailing.comma"; 073 074 @Override 075 public int[] getDefaultTokens() { 076 return getRequiredTokens(); 077 } 078 079 @Override 080 public int[] getAcceptableTokens() { 081 return getRequiredTokens(); 082 } 083 084 @Override 085 public int[] getRequiredTokens() { 086 return new int[] {TokenTypes.ENUM_DEF}; 087 } 088 089 @Override 090 public void visitToken(DetailAST detailAST) { 091 final DetailAST enumBlock = detailAST.findFirstToken(TokenTypes.OBJBLOCK); 092 TokenUtil.findFirstTokenByPredicate(enumBlock, 093 node -> TokenUtil.isOfType(node, TokenTypes.SEMI, TokenTypes.RCURLY)) 094 .map(DetailAST::getPreviousSibling) 095 .filter(token -> token.getType() == TokenTypes.COMMA) 096 .ifPresent(comma -> log(comma, MSG_KEY)); 097 } 098}