1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2026 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.io.File;
23
24 import com.puppycrawl.tools.checkstyle.FileStatefulCheck;
25 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
26 import com.puppycrawl.tools.checkstyle.api.DetailAST;
27 import com.puppycrawl.tools.checkstyle.api.FullIdent;
28 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
29
30 /**
31 * <div>
32 * Ensures that a class has a package declaration, and (optionally) whether
33 * the package name matches the directory name for the source file.
34 * </div>
35 *
36 * <p>
37 * Rationale: Classes that live in the null package cannot be imported.
38 * Many novice developers are not aware of this.
39 * </p>
40 *
41 * <p>
42 * Packages provide logical namespace to classes and should be stored in
43 * the form of directory levels to provide physical grouping to your classes.
44 * These directories are added to the classpath so that your classes
45 * are visible to JVM when it runs the code.
46 * </p>
47 *
48 * @since 3.2
49 */
50 @FileStatefulCheck
51 public final class PackageDeclarationCheck extends AbstractCheck {
52
53 /**
54 * A key is pointing to the warning message text in "messages.properties"
55 * file.
56 */
57 public static final String MSG_KEY_MISSING = "missing.package.declaration";
58
59 /**
60 * A key is pointing to the warning message text in "messages.properties"
61 * file.
62 */
63 public static final String MSG_KEY_MISMATCH = "mismatch.package.directory";
64
65 /** Is package defined. */
66 private boolean defined;
67
68 /**
69 * Whether the file is a JEP 512 compact source file, which lives in the
70 * unnamed package by definition and cannot declare a package.
71 */
72 private boolean isCompactSourceFile;
73
74 /**
75 * Whether the file is a modular compilation unit, which consists of a
76 * module declaration and cannot declare a package.
77 */
78 private boolean isModularCompilationUnit;
79
80 /** Control whether to check for directory and package name match. */
81 private boolean matchDirectoryStructure = true;
82
83 /**
84 * Creates a new {@code PackageDeclarationCheck} instance.
85 */
86 public PackageDeclarationCheck() {
87 // no code by default
88 }
89
90 /**
91 * Setter to control whether to check for directory and package name match.
92 *
93 * @param matchDirectoryStructure the new value.
94 * @since 7.6.1
95 */
96 public void setMatchDirectoryStructure(boolean matchDirectoryStructure) {
97 this.matchDirectoryStructure = matchDirectoryStructure;
98 }
99
100 @Override
101 public int[] getDefaultTokens() {
102 return getRequiredTokens();
103 }
104
105 @Override
106 public int[] getRequiredTokens() {
107 return new int[] {TokenTypes.PACKAGE_DEF};
108 }
109
110 @Override
111 public int[] getAcceptableTokens() {
112 return getRequiredTokens();
113 }
114
115 @Override
116 public void beginTree(DetailAST ast) {
117 defined = false;
118 isCompactSourceFile = ast != null
119 && ast.getType() == TokenTypes.COMPACT_COMPILATION_UNIT;
120 isModularCompilationUnit = ast != null
121 && ast.findFirstToken(TokenTypes.MODULE_DEF) != null;
122 }
123
124 @Override
125 public void finishTree(DetailAST ast) {
126 if (!defined && !isCompactSourceFile && !isModularCompilationUnit && ast != null) {
127 log(ast, MSG_KEY_MISSING);
128 }
129 }
130
131 @Override
132 public void visitToken(DetailAST ast) {
133 defined = true;
134
135 if (matchDirectoryStructure) {
136 final DetailAST packageNameAst = ast.getLastChild().getPreviousSibling();
137 final FullIdent fullIdent = FullIdent.createFullIdent(packageNameAst);
138 final String packageName = fullIdent.getText().replace('.', File.separatorChar);
139
140 final String directoryName = getDirectoryName();
141
142 if (!directoryName.endsWith(packageName)) {
143 log(ast, MSG_KEY_MISMATCH, packageName);
144 }
145 }
146 }
147
148 /**
149 * Returns the directory name this file is in.
150 *
151 * @return Directory name.
152 */
153 private String getDirectoryName() {
154 final String fileName = getFilePath();
155 final int lastSeparatorPos = fileName.lastIndexOf(File.separatorChar);
156 return fileName.substring(0, lastSeparatorPos);
157 }
158
159 }