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why using double sync check on map

 
Greenhorn
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Hello everyone,
in the code, why using double sync check on map instead of using enum for singleton design pattern

 
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jv patel wrote:Hello everyone,
in the code, why using double sync check on map instead of using enum for singleton design pattern



I assume you mean "Double-checked locking". There is no reason to ever use DCL in Java. In fact, before 1.3 or 1.4, the memory model allowed that idiom to fail. I can work in later versions, but there's still no reason to ever use it. I may give very, very small performance gains in lazily instantiated singletons, but there's no reason to lazily instantiate a singleton anyway.

Just forget DCL exists entirely. It's broken and useless.
 
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