The advantage of using static variables in Java

Question

Let's say I have two classes:

class A{  
    private static Random random = new Random();  

    public A(){  
        // Do something.
    }

    public Integer methodGetsCalledQuiteOften(){
        return random.nextInt();
    }
}

class B{  
     private Random random;  

     public A(){  
         random = new Random();
         // Do something.
     }

     public Integer methodGetsCalledQuiteOften(){
         return random.nextInt();
     }
}

In a scenario in which both of them get an instance several times, and the method method of the instances of these classes methodGetsCalledQuiteOftengets a lot of calls, is there any real advantage / disadvantage (time, memory) when using a static variable that runs Random()in class A as opposed to creating a new object Random()in each individual instance, for example, in class B?

The application is multi-threaded and has a higher level of randomness, so I think I'm going with static SecureRandom. If this is a real speed factor after profiling, I could choose something else.

Answer 1

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This saves you from having to transfer references to the initiated object (A or B) to another object in order to use random

Answer 10

Advantages of static variables (highlights):

• Constants can be defined without additional memory (one for each class).

• Access to constants is possible without instantiating the class.

Advantages of static methods:

Undefined behavior can be defined without fear of accidental interaction with an instance of the class.