1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2024 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 java.util.Arrays;
23 import java.util.HashSet;
24 import java.util.Set;
25 import java.util.stream.Collectors;
26
27 import com.puppycrawl.tools.checkstyle.StatelessCheck;
28 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
29 import com.puppycrawl.tools.checkstyle.api.DetailAST;
30 import com.puppycrawl.tools.checkstyle.api.FullIdent;
31 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
32 import com.puppycrawl.tools.checkstyle.utils.CheckUtil;
33
34 /**
35 * <p>
36 * Checks that certain exception types do not appear in a {@code catch} statement.
37 * </p>
38 * <p>
39 * Rationale: catching {@code java.lang.Exception}, {@code java.lang.Error} or
40 * {@code java.lang.RuntimeException} is almost never acceptable.
41 * Novice developers often simply catch Exception in an attempt to handle
42 * multiple exception classes. This unfortunately leads to code that inadvertently
43 * catches {@code NullPointerException}, {@code OutOfMemoryError}, etc.
44 * </p>
45 * <ul>
46 * <li>
47 * Property {@code illegalClassNames} - Specify exception class names to reject.
48 * Type is {@code java.lang.String[]}.
49 * Default value is {@code Error, Exception, RuntimeException, Throwable, java.lang.Error,
50 * java.lang.Exception, java.lang.RuntimeException, java.lang.Throwable}.
51 * </li>
52 * </ul>
53 * <p>
54 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
55 * </p>
56 * <p>
57 * Violation Message Keys:
58 * </p>
59 * <ul>
60 * <li>
61 * {@code illegal.catch}
62 * </li>
63 * </ul>
64 *
65 * @since 3.2
66 */
67 @StatelessCheck
68 public final class IllegalCatchCheck extends AbstractCheck {
69
70 /**
71 * A key is pointing to the warning message text in "messages.properties"
72 * file.
73 */
74 public static final String MSG_KEY = "illegal.catch";
75
76 /** Specify exception class names to reject. */
77 private final Set<String> illegalClassNames = Arrays.stream(new String[] {"Exception", "Error",
78 "RuntimeException", "Throwable", "java.lang.Error", "java.lang.Exception",
79 "java.lang.RuntimeException", "java.lang.Throwable", })
80 .collect(Collectors.toCollection(HashSet::new));
81
82 /**
83 * Setter to specify exception class names to reject.
84 *
85 * @param classNames
86 * array of illegal exception classes
87 * @since 3.2
88 */
89 public void setIllegalClassNames(final String... classNames) {
90 illegalClassNames.clear();
91 illegalClassNames.addAll(
92 CheckUtil.parseClassNames(classNames));
93 }
94
95 @Override
96 public int[] getDefaultTokens() {
97 return getRequiredTokens();
98 }
99
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 }