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 Stri         


        

Answer 1

Add private constructor:

private FilePathHelper(){
    super();
}

Answer 2

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.)

Answer 3

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.

Answer 4

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.

Answer 5

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() {
    }
}

Answer 6

make the utility class final and add a private constructor