Coverage Report

Coverage Report - com.puppycrawl.tools.checkstyle.checks.design.HideUtilityClassConstructorCheck

Classes in this File

Line Coverage

Branch Coverage

Complexity

HideUtilityClassConstructorCheck

100%

38/38

95%

40/42

5.75

 ////////////////////////////////////////////////////////////////////////////////
 // checkstyle: Checks Java source code for adherence to a set of rules.
 // Copyright (C) 2001-2014  Oliver Burn
 //
 // This library is free software; you can redistribute it and/or
 // modify it under the terms of the GNU Lesser General Public
 // License as published by the Free Software Foundation; either
 // version 2.1 of the License, or (at your option) any later version.
 //
 // This library is distributed in the hope that it will be useful,
 // but WITHOUT ANY WARRANTY; without even the implied warranty of
 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 // Lesser General Public License for more details.
 //
 // You should have received a copy of the GNU Lesser General Public
 // License along with this library; if not, write to the Free Software
 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 ////////////////////////////////////////////////////////////////////////////////
 package com.puppycrawl.tools.checkstyle.checks.design;
 
 import com.puppycrawl.tools.checkstyle.api.Check;
 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
 import com.puppycrawl.tools.checkstyle.api.DetailAST;
 
 /**
  * Make sure that utility classes (classes that contain only static methods)
  * do not have a public constructor.
  * <p>
  * Rationale: Instantiating utility classes does not make sense.
  * A common mistake is forgetting to hide the default constructor.
  * </p>
  *
  * @author lkuehne
  */
 public class HideUtilityClassConstructorCheck extends Check
 {
     @Override
     public int[] getDefaultTokens()
     {
         return new int[] {TokenTypes.CLASS_DEF};
     }
 
     @Override
     public void visitToken(DetailAST aAST)
     {
         if (isAbstract(aAST)) {
             // abstract class could not have private constructor
             return;
         }
 
         final DetailAST objBlock = aAST.findFirstToken(TokenTypes.OBJBLOCK);
         DetailAST child = objBlock.getFirstChild();
         final boolean hasStaticModifier = isStatic(aAST);
         boolean hasMethodOrField = false;
         boolean hasNonStaticMethodOrField = false;
         boolean hasNonPrivateStaticMethodOrField = false;
         boolean hasDefaultCtor = true;
         boolean hasPublicCtor = false;
 
         while (child != null) {
             final int type = child.getType();
             if (type == TokenTypes.METHOD_DEF
                     || type == TokenTypes.VARIABLE_DEF)
             {
                 hasMethodOrField = true;
                 final DetailAST modifiers =
                     child.findFirstToken(TokenTypes.MODIFIERS);
                 final boolean isStatic =
                     modifiers.branchContains(TokenTypes.LITERAL_STATIC);
                 final boolean isPrivate =
                     modifiers.branchContains(TokenTypes.LITERAL_PRIVATE);
 
                 if (!isStatic && !isPrivate) {
                     hasNonStaticMethodOrField = true;
                 }
                 if (isStatic && !isPrivate) {
                     hasNonPrivateStaticMethodOrField = true;
                 }
             }
             if (type == TokenTypes.CTOR_DEF) {
                 hasDefaultCtor = false;
                 final DetailAST modifiers =
                     child.findFirstToken(TokenTypes.MODIFIERS);
                 if (!modifiers.branchContains(TokenTypes.LITERAL_PRIVATE)
                     && !modifiers.branchContains(TokenTypes.LITERAL_PROTECTED))
                 {
                     // treat package visible as public
                     // for the purpose of this Check
                     hasPublicCtor = true;
                 }
 
             }
             child = child.getNextSibling();
         }
 
         final boolean hasAccessibleCtor = (hasDefaultCtor || hasPublicCtor);
 
         // figure out if class extends java.lang.object directly
         // keep it simple for now and get a 99% solution
         // TODO: check for "extends java.lang.Object" and "extends Object"
         // consider "import org.omg.CORBA.*"
         final boolean extendsJLO = // J.Lo even made it into in our sources :-)
             aAST.findFirstToken(TokenTypes.EXTENDS_CLAUSE) == null;
 
         final boolean isUtilClass = extendsJLO && hasMethodOrField
             && !hasNonStaticMethodOrField && hasNonPrivateStaticMethodOrField;
 
         if (isUtilClass && (hasAccessibleCtor && !hasStaticModifier)) {
             log(aAST.getLineNo(), aAST.getColumnNo(), "hide.utility.class");
         }
     }
 
     /**
      * @param aAST class definition for check.
      * @return true if a given class declared as abstract.
      */
     private boolean isAbstract(DetailAST aAST)
     {
         return aAST.findFirstToken(TokenTypes.MODIFIERS)
             .branchContains(TokenTypes.ABSTRACT);
     }
 
     /**
      * @param aAST class definition for check.
      * @return true if a given class declared as static.
      */
     private boolean isStatic(DetailAST aAST)
     {
         return aAST.findFirstToken(TokenTypes.MODIFIERS)
             .branchContains(TokenTypes.LITERAL_STATIC);
     }
 }

1		////////////////////////////////////////////////////////////////////////////////
2		// checkstyle: Checks Java source code for adherence to a set of rules.
3		// Copyright (C) 2001-2014 Oliver Burn
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		package com.puppycrawl.tools.checkstyle.checks.design;
20
21		import com.puppycrawl.tools.checkstyle.api.Check;
22		import com.puppycrawl.tools.checkstyle.api.TokenTypes;
23		import com.puppycrawl.tools.checkstyle.api.DetailAST;
24
25		/**
26		* Make sure that utility classes (classes that contain only static methods)
27		* do not have a public constructor.
28		* <p>
29		* Rationale: Instantiating utility classes does not make sense.
30		* A common mistake is forgetting to hide the default constructor.
31		* </p>
32		*
33		* @author lkuehne
34		*/
35	7	public class HideUtilityClassConstructorCheck extends Check
36		{
37		@Override
38		public int[] getDefaultTokens()
39		{
40	7	return new int[] {TokenTypes.CLASS_DEF};
41		}
42
43		@Override
44		public void visitToken(DetailAST aAST)
45		{
46	12	if (isAbstract(aAST)) {
47		// abstract class could not have private constructor
48	2	return;
49		}
50
51	10	final DetailAST objBlock = aAST.findFirstToken(TokenTypes.OBJBLOCK);
52	10	DetailAST child = objBlock.getFirstChild();
53	10	final boolean hasStaticModifier = isStatic(aAST);
54	10	boolean hasMethodOrField = false;
55	10	boolean hasNonStaticMethodOrField = false;
56	10	boolean hasNonPrivateStaticMethodOrField = false;
57	10	boolean hasDefaultCtor = true;
58	10	boolean hasPublicCtor = false;
59
60	58	while (child != null) {
61	48	final int type = child.getType();
62	48	if (type == TokenTypes.METHOD_DEF
63		\|\| type == TokenTypes.VARIABLE_DEF)
64		{
65	21	hasMethodOrField = true;
66	21	final DetailAST modifiers =
67		child.findFirstToken(TokenTypes.MODIFIERS);
68	21	final boolean isStatic =
69		modifiers.branchContains(TokenTypes.LITERAL_STATIC);
70	21	final boolean isPrivate =
71		modifiers.branchContains(TokenTypes.LITERAL_PRIVATE);
72
73	21	if (!isStatic && !isPrivate) {
74	7	hasNonStaticMethodOrField = true;
75		}
76	21	if (isStatic && !isPrivate) {
77	6	hasNonPrivateStaticMethodOrField = true;
78		}
79		}
80	48	if (type == TokenTypes.CTOR_DEF) {
81	4	hasDefaultCtor = false;
82	4	final DetailAST modifiers =
83		child.findFirstToken(TokenTypes.MODIFIERS);
84	4	if (!modifiers.branchContains(TokenTypes.LITERAL_PRIVATE)
85		&& !modifiers.branchContains(TokenTypes.LITERAL_PROTECTED))
86		{
87		// treat package visible as public
88		// for the purpose of this Check
89	3	hasPublicCtor = true;
90		}
91
92		}
93	48	child = child.getNextSibling();
94	48	}
95
96	10	final boolean hasAccessibleCtor = (hasDefaultCtor \|\| hasPublicCtor);
97
98		// figure out if class extends java.lang.object directly
99		// keep it simple for now and get a 99% solution
100		// TODO: check for "extends java.lang.Object" and "extends Object"
101		// consider "import org.omg.CORBA.*"
102	10	final boolean extendsJLO = // J.Lo even made it into in our sources :-)
103		aAST.findFirstToken(TokenTypes.EXTENDS_CLAUSE) == null;
104
105	10	final boolean isUtilClass = extendsJLO && hasMethodOrField
106		&& !hasNonStaticMethodOrField && hasNonPrivateStaticMethodOrField;
107
108	10	if (isUtilClass && (hasAccessibleCtor && !hasStaticModifier)) {
109	1	log(aAST.getLineNo(), aAST.getColumnNo(), "hide.utility.class");
110		}
111	10	}
112
113		/**
114		* @param aAST class definition for check.
115		* @return true if a given class declared as abstract.
116		*/
117		private boolean isAbstract(DetailAST aAST)
118		{
119	12	return aAST.findFirstToken(TokenTypes.MODIFIERS)
120		.branchContains(TokenTypes.ABSTRACT);
121		}
122
123		/**
124		* @param aAST class definition for check.
125		* @return true if a given class declared as static.
126		*/
127		private boolean isStatic(DetailAST aAST)
128		{
129	10	return aAST.findFirstToken(TokenTypes.MODIFIERS)
130		.branchContains(TokenTypes.LITERAL_STATIC);
131		}
132		}