How can I pass an object to a function by value?

Hi
I have a function with an argument. this argument is an object. I don't want to alter this object. But java passes this object by reference and some fields in this object are altered after function return.
How can I pass this object by value and keep my original data unbroken?
thanks for any help

a.toraby wrote:
I have a function with an argument. this argument is an object. I don't want to alter this object. But java passes this object by reference and some fields in this object are altered after function return.
How can I pass this object by value and keep my original data unbroken?How you approach it is likely to depend on how much control you have over the code in question. If it's legacy code and has been badly designed, there's probably very little you can do to protect existing code short of a complete refactoring.
What you could do as an interim measure is:
1. Create an immutable wrapper to your existing mutable class.
2. Create new methods that replicate the existing ones, but take the immutable class instead.
3. Deprecate the old methods.
This won't break client code, but they will now get warnings when they compile and you can add documentation to point them to the new class/methods.
If you are in control of the code (especially if you're still in the design stages), you've got several options:
1. As Dr.Clap says, make your class immutable (probably best).
2. If this isn't possible, create mutable and immutable variants of your class. This is often best achieved by hanging them both from an interface.
Winston

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