019 – Effective Java for Android developers : Item 4

Singer and Android developer Donn Felker explores Joshua Bloch's fourth Item: Enforce noninstantiability with a private constructor.
Stay tuned, cause we got more of these quick ones coming.

 
Show notes for this episode:

Effective Java (2nd Edition) - Joshua Bloch

Enforce noninstantiability with a private constructor.
Examples where you don't want class to be instantiated

class that groups static methods and static fields (Util like classes think java.lang.Math/java.util.Arrays)
class that groups static methods (including factory methods) for objects implementing specific interfaces (think java.util.Collections)
class that group methods on a final class (vs. extending the class)

Considerations

Makes no sense to instantiate such "Util" classes
Private constructors prevent instantiation
Important side effect: prevents subclassing

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