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