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Say I have one class ClassBig with 100 methods inside, and a second with only 10 methods ClassSmall
When I have objects at runtime
ClassBig big = new ClassBig();
ClassSmall small = new ClassSmall();
Does the larger class take up more memory space?
If both classes contained an identical method, does the larger class take longer to execute it?
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Yes, creating functions uses more memory.
The number of methods that may be declared by a class or interface is limited to 65535 by the size of the methods_count item of the ClassFile structure (§4.1).
The class takes up at least 8 bytes. So, if you say new Object(); you will allocate 8 bytes on the heap. Each data member takes up 4 bytes, except for long and double which take up 8 bytes. Even if the data member is a byte, it will still take up 4 bytes!
In general a class or struct is a concept and does not occupy variable (data) space, but it does take up memory in the compiler's memory.
The in-memory representation of an instance of a class is mainly just its internal state plus a pointer to an in-memory representation of the class itself. The internal representation of an instance method has one more argument than you specified in the class definition - the implicit this reference. This is how we can store only one copy of the instance method, rather than a new copy for every instance.
So a class with more methods will take up more memory than a class with less methods (the code has to go somewhere), but an instance of a class with more methods will use the same amount of memory, assuming the classes have the same data members.
Execution time will not be affected by the number of other methods in the class.
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