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