Creation of Objects: Constructors or Static Factory Methods

Posted by Rachel on Stack Overflow See other posts from Stack Overflow or by Rachel
Published on 2011-01-06T16:44:19Z Indexed on 2011/01/06 16:53 UTC
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I am going through Effective Java and some of my things which I consider as standard are not suggested by the book, for instance creation of object, I was under the impression that constructors are the best way of doing it and books says we should make use of static factory methods, I am not able to few some advantages and so disadvantages and so am asking this question, here are the benefits of using it.

Advantages:

  1. One advantage of static factory methods is that, unlike constructors, they have names.
  2. A second advantage of static factory methods is that, unlike constructors, they are not required to create a new object each time they’re invoked.
  3. A third advantage of static factory methods is that, unlike constructors, they can return an object of any subtype of their return type.
  4. A fourth advantage of static factory methods is that they reduce the verbosity of creating parameterized type instances. I am not able to understand this advantage and would appreciate if someone can explain this point

Disadvantages:

  1. The main disadvantage of providing only static factory methods is that classes without public or protected constructors cannot be subclassed.
  2. A second disadvantage of static factory methods is that they are not readily distinguishable from other static methods.I am not getting this point and so would really appreciate some explanation.

Reference: Effective Java, Joshua Bloch, Edition 2, pg: 5-10

Also, How to decide to use whether to go for Constructor or Static Factory Method for Object Creation ?

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