Java singleton usage -

Java singleton usage -

specifically in java, uses of singletons? seems whatever can done singleton can done static methods , variables. there i'm missing. many users suggest lazy loading reason looks that's not benefit in java.

the benefit can think of implementation enhanced though overridden implementation in new class, substituted in getinstance() method.

update/edit:

advantage of singleton on static former more object oriented later. singleton, can utilize inheritance , polymorphism extend base of operations class, implement interface , provide different implementations.

(looks way accomplish results similar overriding of static methods in java.)

are there other advantages aswell?

the wikipedia page on pattern indicates several mutual uses:

facade objects singletons because 1 facade object required.

state objects singletons (i.e. global state).

singletons preferred global variables because:

they not pollute global namespace (or, in languages namespaces, containing namespace) unnecessary variables. they permit lazy allocation , initialization, whereas global variables in many languages consume resources.

effective java recommends create singleton using single value enum prevent multiple instances beingness created. prevents subclassing. have side effect of making testing harder.

one of benefits of using singleton becomes much easier command concurrent access, singleton object ideal locking object synchronisation.

java singleton static-methods factory