Is it faster to call a method as I initialise an object or hold it as a variable and call the method on that

Question

Assuming that there is a class ClassA which gives a value that I need through non-static method.

In case when I just need a value from an instance of the ClassA, I guess there are two possible choices.

double value =0 ; // The value I actually need, the object is just transitory

1) ClassA a = new ClassA (hogehoge);
   value = a.getValue();

2) value = new ClassA(hogehoge).getValue();

I know there maybe an advantage or disadvantage for both. but generally speaking what is the difference between them?

in case 2), memory use is smaller than 1) or....

Answer 1

Actually this two piece of code will have a small difference:

***** Class1.p
       8: invokespecial #4                  // Method ClassA."<init>":(Ljava/lang/String;)V
      11: astore_3
      12: aload_3
      13: invokevirtual #5                  // Method ClassA.getValue:()D
      16: dstore_1
      17: dload_1
      18: dreturn
}
***** CLASS2.P
       8: invokespecial #4                  // Method ClassA."<init>":(Ljava/lang/String;)V
      11: invokevirtual #5                  // Method ClassA.getValue:()D
      14: dstore_1
      15: dload_1
      16: dreturn
}
*****

I.e. we see here two additional instructions for variant #1:

      11: astore_3
      12: aload_3

But it seems, that after jvm warms-up these instructions will be optimized (eliminated) and it will be no difference at all.