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Builder will be enriched with each method call. Each method will return same Builder object. Builder class will expose method for adding ingredients e.g.Builder class will have exactly same set of fields as original class.Make a static nested class called Builder inside the class whose object will be build by Builder.Guidelines for Builder design pattern in Java Finally the client calls a build method which generate an instance of the object which is immutable. Then the client calls methods on the builder object to set each optional parameters. Instead of making the desired object directly, the client calls a constructor (or static factory) with all of the required parameters and gets a builder object. And you can construct the object in a multi-step, self-documenting fashion, which is one of the nice features of the JavaBeans model, but without the possibility of leaving an object in an inconsistent state. Some may be required, others are optional. It is a form of the Builder pattern It allows objects to be constructed with any number of variable attributes and settings. There is however third approach that is very elegant and can create immutable objects. Second is that this pattern pre-cludes the possibility of making a class immutable. First is that JavaBean may be in an inconsistent state partway through its construction. There are two problems with this approach. Second approach is to use JavaBeans in which you call a parameter-less constructor to create the object and then call setter methods to set each required parameter and each optional parameter of interest. This approach has obvious disadvantages (ugly code, lot of work).
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First is telescopic constructors where you need to create constructor for each of optional parameter. There number of ways that developers usually try to approach this problem.
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Problem starts when an Object can be created with lot of parameters, some of them may be mandatory and others may be optional. The Builder Design Pattern comes under the creational pattern type.Ĭonstructors in Java are used to create object and can take parameters required to create object.