object-oriented programming Object-oriented programming (OOP) is a programming paradigm based on the concept of " objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of ...

, a helper class is used to assist in providing some functionality, which isn't the main goal of the application or class in which it is used . An instance of a helper class is called a helper object (for example, in the

delegation pattern In software engineering, the delegation pattern is an object-oriented design pattern that allows object composition to achieve the same code reuse as inheritance. In delegation, an object handles a request by delegating to a second object (the ''de ...

). Helper classes are often created in introductory programming lessons, after the novice programmer has moved beyond creating one or two classes. A

utility class As a topic of economics, utility is used to model worth or value. Its usage has evolved significantly over time. The term was introduced initially as a measure of pleasure or happiness as part of the theory of utilitarianism by moral philosop ...

is a special case of a helper class in which the methods are all static. In general, helper classes do not have to have all static methods, but may have instance variables. Multiple instances of the helper class may exist as well.

Example

This is also an example of a

. public static class PrependHelper

Alternative to helper class

Functions which are going to helper classes could be placed close to where they are used. The other alternative is wrapping helper class parameters into a class as a field. That class can have a name from the business domain connected to the fields it has. The example below shows how to convert helper methods to methods on domain types: public class Text

Example

Alternative to helper class

See also