Singleton class, private variable or method parameter. Performance

Question

I got 3 classes, A,B and C.

Only 1 instance of class A exits at any given time but hundreds of objects of class B and C will exist.

Class A calls a method of class B. Class B calls a method of class C. And class C eventually calls a method of the class A object.

What would be the best and cleanest way to provide the reference to the class A object in C?

Saving it in a private variable and initializing it via the constructor?
Creating a static getInstance() method in Class A which returns the object itself?
Or passing "this" through parameters from A to B to C?

Any C Object will call the method of A multiple time in his lifetime.

@HotLicks #1: I mean that during the creation of object's of type B or C I could pass the object of class A as a reference and save it in a private variable in every object of B or C — user3394605, Oct 22 '14 at 19:59
That's probably the best choice, if you're reasonably sure that part of the design won't change. — Hot Licks, Oct 22 '14 at 20:02

score 0 · Answer 1 · answered Oct 22 '14 at 20:01

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I would suggest create a static getInstance() method in Class A which returns the object itself.

answered Oct 22 '14 at 20:01

Anand Rathi

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score 0 · Answer 2 · answered Oct 22 '14 at 20:05

Option 2. Have your Singleton class contain the instance privately with a private constructor and return the instance using get instance. This the commonly used pattern.

Option 1 makes the constructor open to other methods which is not needed since it should only be called once (if I'm reading the option correctly). Option 3 will clutter your code.

score 0 · Accepted Answer · edited May 23 '17 at 11:49

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The most convenient way is certainly #2. The "cleanest" is probably #1, or #3, depending on the circumstances.

The Singleton (#2) pattern has some problems. That does not mean you should avoid it at all costs. But you should be aware of the implications.

For some information on the topic see What is so bad about singletons?

edited May 23 '17 at 11:49

Community

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answered Oct 22 '14 at 20:12

Thomas Stets

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Thanks I will use this approach being aware of the limitations and the problems. – user3394605 Oct 22 '14 at 20:26

Singleton class, private variable or method parameter. Performance

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