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In Effective Java , Item 1, it says that the static factory methods made the Collections framework much smaller than it would have been. Could someone please explain how ? I can't understand how the following is possible just because of using static factory methods ? I mean we still have to implement those separate implementations don't we ?
The Collections Framework API is much smaller than it would have been had it exported thirty-two separate public classes, one for each convenience implementation.
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Static factory methods can have meaningful names, hence explicitly conveying what they do. Static factory methods can return the same type that implements the method(s), a subtype, and also primitives, so they offer a more flexible range of returning types.
The static factory method pattern is a way to encapsulate object creation.
The main disadvantage of providing only static factory methods is that classes without public or protected constructors cannot be subclassed.
getInstance() method of java. util. Calendar, NumberFormat, and ResourceBundle uses factory method design pattern.
By "smaller" they mean "less classes".
Instead of providing lots of classes for each variation of implementation, instead factory methods have been provided that return such implementations without the need to have their classes declared as top-level classes (less "class bloat").
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