001/////////////////////////////////////////////////////////////////////////////////////////////// 002// checkstyle: Checks Java source code and other text files for adherence to a set of rules. 003// Copyright (C) 2001-2023 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; 026 027/** 028 * <p> 029 * Checks that array initialization do not contain a trailing comma. 030 * Rationale: JLS allows trailing commas in arrays and enumerations, but does not allow 031 * them in other locations. To unify the coding style, the use of trailing commas should 032 * be prohibited. 033 * </p> 034 * <pre> 035 * int[] foo = new int[] { 036 * 1, 037 * 2 038 * }; 039 * </pre> 040 * <p> 041 * The check demands that there should not be any comma after the last element of an array. 042 * </p> 043 * <pre> 044 * String[] foo = new String[] { 045 * "FOO", 046 * "BAR", //violation 047 * } 048 * </pre> 049 * <p> 050 * To configure the check: 051 * </p> 052 * <pre> 053 * <module name="NoArrayTrailingComma"/> 054 * </pre> 055 * <p> 056 * Which results in the following violations: 057 * </p> 058 * <pre> 059 * String[] foo1 = { 060 * "FOO", // OK 061 * "BAR", // violation 062 * }; 063 * String[] foo2 = { "FOO", "BAR", }; // violation 064 * String[] foo3 = { 065 * "FOO", // OK 066 * "BAR" // OK 067 * }; 068 * String[] foo4 = { "FOO", "BAR" }; // OK 069 * </pre> 070 * <p> 071 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 072 * </p> 073 * <p> 074 * Violation Message Keys: 075 * </p> 076 * <ul> 077 * <li> 078 * {@code no.array.trailing.comma} 079 * </li> 080 * </ul> 081 * 082 * @since 8.28 083 */ 084@StatelessCheck 085public class NoArrayTrailingCommaCheck extends AbstractCheck { 086 087 /** 088 * A key is pointing to the warning message text in "messages.properties" 089 * file. 090 */ 091 public static final String MSG_KEY = "no.array.trailing.comma"; 092 093 @Override 094 public int[] getDefaultTokens() { 095 return getRequiredTokens(); 096 } 097 098 @Override 099 public int[] getAcceptableTokens() { 100 return getRequiredTokens(); 101 } 102 103 @Override 104 public int[] getRequiredTokens() { 105 return new int[] {TokenTypes.ARRAY_INIT}; 106 } 107 108 @Override 109 public void visitToken(DetailAST arrayInit) { 110 final DetailAST rcurly = arrayInit.findFirstToken(TokenTypes.RCURLY); 111 final DetailAST previousSibling = rcurly.getPreviousSibling(); 112 if (previousSibling != null && previousSibling.getType() == TokenTypes.COMMA) { 113 log(previousSibling, MSG_KEY); 114 } 115 } 116}