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Explore different Java Singleton pattern implementations with a focus on thread safety and resource management. Understand eager and lazy initialization techniques, synchronized methods, and advanced approaches like double-checked locking and the Bill Pugh Singleton for safe and efficient singleton usage.
We'll cover the following...
Implementing a thread-safe Singleton class is a popular interview question with the double checked locking as the most debated implementation. For completeness, we present below all the various evolutions of the Singleton pattern in Java.
The easiest way to create a singleton is to mark the constructor of the class private and create a private static instance of the class that is initialized inline. The instance is returned through a public getter method. The drawback of this approach is if the singleton object is never used then we have spent resources creating and retaining the object in memory. The static member is initialized when the class is loaded. Additionally, the singleton instance can be expensive to create and we may want to delay creating the object till it is actually ...