1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2025 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.imports;
21
22 import java.util.HashSet;
23 import java.util.Set;
24
25 import com.puppycrawl.tools.checkstyle.StatelessCheck;
26 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
27 import com.puppycrawl.tools.checkstyle.api.DetailAST;
28 import com.puppycrawl.tools.checkstyle.api.FullIdent;
29 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
30
31 /**
32 * <div>
33 * Checks that there are no import statements that use the {@code *} notation.
34 * </div>
35 *
36 * <p>
37 * Rationale: Importing all classes from a package or static
38 * members from a class leads to tight coupling between packages
39 * or classes and might lead to problems when a new version of a
40 * library introduces name clashes.
41 * </p>
42 *
43 * <p>
44 * Notes:
45 * Note that property {@code excludes} is not recursive, subpackages of excluded
46 * packages are not automatically excluded.
47 * </p>
48 *
49 * @since 3.0
50 */
51 @StatelessCheck
52 public class AvoidStarImportCheck
53 extends AbstractCheck {
54
55 /**
56 * A key is pointing to the warning message text in "messages.properties"
57 * file.
58 */
59 public static final String MSG_KEY = "import.avoidStar";
60
61 /** Suffix for the star import. */
62 private static final String STAR_IMPORT_SUFFIX = ".*";
63
64 /**
65 * Specify packages where starred class imports are
66 * allowed and classes where starred static member imports are allowed.
67 */
68 private final Set<String> excludes = new HashSet<>();
69
70 /**
71 * Control whether to allow starred class imports like
72 * {@code import java.util.*;}.
73 */
74 private boolean allowClassImports;
75
76 /**
77 * Control whether to allow starred static member imports like
78 * {@code import static org.junit.Assert.*;}.
79 */
80 private boolean allowStaticMemberImports;
81
82 @Override
83 public int[] getDefaultTokens() {
84 return getRequiredTokens();
85 }
86
87 @Override
88 public int[] getAcceptableTokens() {
89 return getRequiredTokens();
90 }
91
92 @Override
93 public int[] getRequiredTokens() {
94 // original implementation checks both IMPORT and STATIC_IMPORT tokens to avoid ".*" imports
95 // however user can allow using "import" or "import static"
96 // by configuring allowClassImports and allowStaticMemberImports
97 // To avoid potential confusion when user specifies conflicting options on configuration
98 // (see example below) we are adding both tokens to Required list
99 // <module name="AvoidStarImport">
100 // <property name="tokens" value="IMPORT"/>
101 // <property name="allowStaticMemberImports" value="false"/>
102 // </module>
103 return new int[] {TokenTypes.IMPORT, TokenTypes.STATIC_IMPORT};
104 }
105
106 /**
107 * Setter to specify packages where starred class imports are
108 * allowed and classes where starred static member imports are allowed.
109 *
110 * @param excludesParam package names/fully-qualifies class names
111 * where star imports are ok
112 * @since 3.2
113 */
114 public void setExcludes(String... excludesParam) {
115 for (final String exclude : excludesParam) {
116 if (exclude.endsWith(STAR_IMPORT_SUFFIX)) {
117 excludes.add(exclude);
118 }
119 else {
120 excludes.add(exclude + STAR_IMPORT_SUFFIX);
121 }
122 }
123 }
124
125 /**
126 * Setter to control whether to allow starred class imports like
127 * {@code import java.util.*;}.
128 *
129 * @param allow true to allow false to disallow
130 * @since 5.3
131 */
132 public void setAllowClassImports(boolean allow) {
133 allowClassImports = allow;
134 }
135
136 /**
137 * Setter to control whether to allow starred static member imports like
138 * {@code import static org.junit.Assert.*;}.
139 *
140 * @param allow true to allow false to disallow
141 * @since 5.3
142 */
143 public void setAllowStaticMemberImports(boolean allow) {
144 allowStaticMemberImports = allow;
145 }
146
147 @Override
148 public void visitToken(final DetailAST ast) {
149 if (ast.getType() == TokenTypes.IMPORT) {
150 if (!allowClassImports) {
151 final DetailAST startingDot = ast.getFirstChild();
152 logsStarredImportViolation(startingDot);
153 }
154 }
155 else if (!allowStaticMemberImports) {
156 // must navigate past the static keyword
157 final DetailAST startingDot = ast.getFirstChild().getNextSibling();
158 logsStarredImportViolation(startingDot);
159 }
160 }
161
162 /**
163 * Gets the full import identifier. If the import is a starred import and
164 * it's not excluded then a violation is logged.
165 *
166 * @param startingDot the starting dot for the import statement
167 */
168 private void logsStarredImportViolation(DetailAST startingDot) {
169 final FullIdent name = FullIdent.createFullIdent(startingDot);
170 final String importText = name.getText();
171 if (importText.endsWith(STAR_IMPORT_SUFFIX) && !excludes.contains(importText)) {
172 log(startingDot, MSG_KEY, importText);
173 }
174 }
175
176 }