Recently I was in a discussion with a coworker on the benefits of using Utility classes over putting common functions in an Abstract class. These classes usually contain static methods that perform common functions.  The major argument I gave was it allowed me to add functions later on without being concerned about all the classes that inherited from it.  The vast amount of my coding style is a functional/Object oriented hybrid.  Objects classes which call Utility classes. After that discussion I wondered what was the performance implications. So I wrote a Calculator app using both approaches and ran each 500,000 times to get an average performance. Here is what I found: 

• Classes that inherit code from Abstract classes are around 30% slower to initialize.
• Classes that inherit code from Abstract classes are around 4% slower in execution of all their inherited methods versus calling all the methods from a Utility class.
• Classes that inherit code from Abstract classes are around 1.3% larger in compiled size.
• After examining the heap dump I found memory usage is indistinguishable between the two. 

Frankly the compiled size and execution speed fall under standard error. However initialization time is indeed a performance differentiator. Ultimately I believe this is why many of the classes in Java use static Utility classes from the java.util package. Now this is not to say that abstract classes don't have their time and place. On the contrary, they can become very useful and save you a good amount of code. However unless you are inheriting a data modal then I suggest you leave common functions to Utility classes. 

 

If you have any thought or advice, please leave them in the comments below.