Question

I’m wondering if it is a good style to inject utility methods with google guice.

Let’s say we have a Converter Utility Class:

public class UtilClass
{
  public static Result convert(Source src)
  {
    //Do conversion

    return result;
  }
}

My idea is to use guice to inject this Utility as Singleton like this

@Singleton
public class UtilClass
{
  public Result convert(Source src)
  {
    //Do conversion

    return result;
  }
}

Which way is recommended for an Application built with guice?

Answer 1

It depends on the nature of your convert() method.

If it’s something

• simple
• deterministic (i.e. doesn’t depend on additional parameters)
• have no side effects
• is unlikely to change
• etc

you can keep it as a static utility method.

Otherwise it’s a good candidate for dependecy injection (you can rename it to ConversionService to make it more clear).