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 java.util.Arrays; 023import java.util.HashSet; 024import java.util.Set; 025import java.util.stream.Collectors; 026 027import com.puppycrawl.tools.checkstyle.StatelessCheck; 028import com.puppycrawl.tools.checkstyle.api.AbstractCheck; 029import com.puppycrawl.tools.checkstyle.api.DetailAST; 030import com.puppycrawl.tools.checkstyle.api.FullIdent; 031import com.puppycrawl.tools.checkstyle.api.TokenTypes; 032import com.puppycrawl.tools.checkstyle.utils.CheckUtil; 033 034/** 035 * <div> 036 * Checks that certain exception types do not appear in a {@code catch} statement. 037 * </div> 038 * 039 * <p> 040 * Rationale: catching {@code java.lang.Exception}, {@code java.lang.Error} or 041 * {@code java.lang.RuntimeException} is almost never acceptable. 042 * Novice developers often simply catch Exception in an attempt to handle 043 * multiple exception classes. This unfortunately leads to code that inadvertently 044 * catches {@code NullPointerException}, {@code OutOfMemoryError}, etc. 045 * </p> 046 * <ul> 047 * <li> 048 * Property {@code illegalClassNames} - Specify exception class names to reject. 049 * Type is {@code java.lang.String[]}. 050 * Default value is {@code Error, Exception, RuntimeException, Throwable, java.lang.Error, 051 * java.lang.Exception, java.lang.RuntimeException, java.lang.Throwable}. 052 * </li> 053 * </ul> 054 * 055 * <p> 056 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 057 * </p> 058 * 059 * <p> 060 * Violation Message Keys: 061 * </p> 062 * <ul> 063 * <li> 064 * {@code illegal.catch} 065 * </li> 066 * </ul> 067 * 068 * @since 3.2 069 */ 070@StatelessCheck 071public final class IllegalCatchCheck extends AbstractCheck { 072 073 /** 074 * A key is pointing to the warning message text in "messages.properties" 075 * file. 076 */ 077 public static final String MSG_KEY = "illegal.catch"; 078 079 /** Specify exception class names to reject. */ 080 private final Set<String> illegalClassNames = Arrays.stream(new String[] {"Exception", "Error", 081 "RuntimeException", "Throwable", "java.lang.Error", "java.lang.Exception", 082 "java.lang.RuntimeException", "java.lang.Throwable", }) 083 .collect(Collectors.toCollection(HashSet::new)); 084 085 /** 086 * Setter to specify exception class names to reject. 087 * 088 * @param classNames 089 * array of illegal exception classes 090 * @since 3.2 091 */ 092 public void setIllegalClassNames(final String... classNames) { 093 illegalClassNames.clear(); 094 illegalClassNames.addAll( 095 CheckUtil.parseClassNames(classNames)); 096 } 097 098 @Override 099 public int[] getDefaultTokens() { 100 return getRequiredTokens(); 101 } 102 103 @Override 104 public int[] getRequiredTokens() { 105 return new int[] {TokenTypes.LITERAL_CATCH}; 106 } 107 108 @Override 109 public int[] getAcceptableTokens() { 110 return getRequiredTokens(); 111 } 112 113 @Override 114 public void visitToken(DetailAST detailAST) { 115 final DetailAST parameterDef = 116 detailAST.findFirstToken(TokenTypes.PARAMETER_DEF); 117 final DetailAST excTypeParent = 118 parameterDef.findFirstToken(TokenTypes.TYPE); 119 120 DetailAST currentNode = excTypeParent.getFirstChild(); 121 while (currentNode != null) { 122 final FullIdent ident = FullIdent.createFullIdent(currentNode); 123 final String identText = ident.getText(); 124 if (illegalClassNames.contains(identText)) { 125 log(detailAST, MSG_KEY, identText); 126 } 127 currentNode = currentNode.getNextSibling(); 128 } 129 } 130}