Moving Features between Objects
Even if you have distributed functionality among different classes in a less-than-perfect way, there is still hope.
These refactoring techniques show how to safely move functionality between classes, create new classes, and hide implementation details from public access.
Problem: A method is used more in another class than in its own class. Solution: Create a new method in the class that uses the method the most, then move code from the old method to there. Turn the code of the original method into a reference to the new method in the other class or else remove it entirely.
Problem: A field is used more in another class than in its own class. Solution: Create a field in a new class and redirect all users of the old field to it.
Problem: When one class does the work of two, awkwardness results. Solution: Instead, create a new class and place the fields and methods responsible for the relevant functionality in it.
Problem: A class does almost nothing and is not responsible for anything, and no additional responsibilities are planned for it. Solution: Solution: Move all features from the class to another one.
Problem: The client gets object B from a field or method of object А. Then the client calls a method of object B. Solution: Create a new method in class A that delegates the call to object B. Now the client does not know about, or depend on, class B.
Remove Middle Man
Problem: A class has too many methods that simply delegate to other objects. Solution: Delete these methods and force the client to call the end methods directly.
Introduce Foreign Method
Problem: A utility class does not contain the method that you need and you cannot add the method to the class. Solution: Add the method to a client class and pass an object of the utility class to it as an argument.
Introduce Local Extension
Problem: A utility class does not contain some methods that you need. But you cannot add these methods to the class. Solution: Create a new class containing the methods and make it either the child or wrapper of the utility class.