Knowing the memory size of an object

[Philipp]

Hello
In my application I use the standard swing "undo" system. Some
UndoableEdit take very little memory and some take a lot. Instead of
specifying a number of undo _levels_, I would prefer to specify a max
amount of memory dedicated to the undo system (for one given UndoManager).

How could I implement this? Can I construct my UndoableEdit and then
measure its size and add this memory value to the UndoManager which will
drop the oldest edit if the memory is above a threshold?

Thanks for any advices
Phil

 

[Tom Hawtin]

In my application I use the standard swing "undo" system. Some
UndoableEdit take very little memory and some take a lot. Instead of
specifying a number of undo _levels_, I would prefer to specify a max
amount of memory dedicated to the undo system (for one given UndoManager).

How could I implement this? Can I construct my UndoableEdit and then
measure its size and add this memory value to the UndoManager which will
drop the oldest edit if the memory is above a threshold?

In general you can't really measure object size in Java, although you
can estimate.

What you might be able to do is serialise the edits. However, I don't
know quite how badly serialisation is implemented in this area.

Tom Hawtin