Hide Utility Class Constructor Utility classes should not have a public or default constructor

Question

I am getting this warning on Sonar I want solution to remove this warning on sonar  My class is like this    public class FilePathHelper       private static String resourcesPath       public static String getFilePath HttpServletRequest request            if resourcesPath    null                String serverpath request getSession   getServletContext   getRealPath                               resourcesPath   serverpath     WEB-INF classes                         return resourcesPath                   i want proper solution to remove this warning on sonar

User · Answer

make the utility class final and add a private constructor

User · Answer

I don t know Sonar  but I suspect it s looking for a private constructor  private FilePathHelper            No-op  won t be called    Otherwise the Java compiler will provide a public parameterless constructor  which you really don t want   You should also make the class final  although other classes wouldn t be able to extend it anyway due to it only having a private constructor

User · Answer

Best practice is to throw an error if the class is constructed    Example          The Class FooUtilityService      final class FooUtilityService         Instantiates a new FooUtilityService  Private to prevent instantiation    private FooUtilityService             Throw an exception if this ever  is  called     throw new AssertionError  Instantiating utility class

User · Answer

Add private constructor   private FilePathHelper        super

User · Answer

If this class is only a utility class  you should make the class final and define a private constructor   public final class FilePathHelper       private FilePathHelper             not called          This prevents the default parameter-less constructor from being used elsewhere in your code  Additionally  you can make the class final  so that it can t be extended in subclasses  which is a best practice for utility classes  Since you declared only a private constructor  other classes wouldn t be able to extend it anyway  but it is still a best practice to mark the class as final

User · Answer

You can just use Lombok with access level PRIVATE in  NoArgsConstructor annotation to avoid unnecessary initialization    NoArgsConstructor access   AccessLevel PRIVATE   public class FilePathHelper       your code

User · Answer

SonarQube documentation recommends adding static keyword to the class declaration   That is  change public class FilePathHelper to public static class FilePathHelper   Alternatively you can add a private or protected constructor   public class FilePathHelper          private or protected constructor        because all public fields and methods are static     private FilePathHelper

User · Answer

I use an enum with no instances  public enum MyUtils             no instances        class is final and the constructor is private      public static int myUtilityMethod int x            return x   x            you can call this using  int y   MyUtils myUtilityMethod 5      returns 25

User · Answer

public class LmsEmpWfhUtils           private LmsEmpWfhUtils                  prevents access default paramater-less constructor           This prevents the default parameter-less constructor from being used elsewhere in your code

User · Answer

I recommend just disabling this rule in Sonar  there is no real benefit of introducing a private constructor  just redundant characters in your codebase other people need to read and computer needs to store and process

[java] Hide Utility Class Constructor : Utility classes should not have a public or default constructor

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