Then delete the conditional and declare the method abstract. Repeat replacement until the conditional is empty. ![]() If the conditional is in a method that performs other actions as well, perform Extract Method.įor each hierarchy subclass, redefine the method that contains the conditional and copy the code of the corresponding conditional branch to that location. The following steps assume that you have already created the hierarchy. The current class will contain references to the objects of this type and delegate execution to them. A class will be dedicated for a particular object property and subclasses will be created from it for each value of the property. This approach is simple but less flexible since you can’t create subclasses for the other properties of the object. Due to this, all objects in Java are polymorphic because they pass at. Subclasses will be created for all values of a particular object property. As described in our post about inheritance, all Java classes extend the class Object. Other techniques will help to make this happen: If you don’t have a hierarchy like this, create one. ![]() If you need to add a new execution variant, all you need to do is add a new subclass without touching the existing code ( Open/Closed Principle).įor this refactoring technique, you should have a ready hierarchy of classes that will contain alternative behaviors. Instantiation The new keyword is used to create the object. Declaration A variable declaration with a variable name with an object type. There are three steps when creating an object from a class. In Java, the new keyword is used to create new objects. You get rid of many almost identical conditionals. So basically, an object is created from a class. This technique adheres to the Tell-Don’t-Ask principle: instead of asking an object about its state and then performing actions based on this, it’s much easier to simply tell the object what it needs to do and let it decide for itself how to do that. Thus the benefit of this technique is multiplied if there are multiple conditionals scattered throughout all of an object’s methods. If a new object property or type appears, you will need to search for and add code in all similar conditionals. Result of calling one of an object’s methods ![]() This refactoring technique can help if your code contains operators performing various tasks that vary based on:Ĭlass of the object or interface that it implements in the context of extension methods you would like to have polymorphic behavior. Return (isNailed) ? 0 : getBaseSpeed(voltage) The class declaration reuses a lot of Javas syntax but still is a bit. Return getBaseSpeed() - getLoadFactor() * numberOfCoconuts
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