Will the original object be affected by this code?

Question

A friend of mine wrote such code:

public AccountModel updateAccountPotential(Long accId) {

    AccountModel accModel = accountDAO.findById(accId);

    this.calculatePotential(accModel);
    return accountDAO.save(accModel);
}

private void calculatePotential(AccountModel accModel) {
    accModel.setPotential(some formula);
}

There's this method calculatePotential that returns nothing, but does some operations on parameter's field. Will that affect the original object in updateAccountPotential method?

**Yes**, because https://stackoverflow.com/questions/40480/is-java-pass-by-reference-or-pass-by-value . — luk2302, Aug 07 '18 at 08:16
It would be nice to see the AccountModel::setPotencial method, but I guess is a "typical" setter so, yes, original object will be affected — Héctor, Aug 07 '18 at 08:16
`accModel.setPotential(some formula);` will definitely affect the `accModel`... — deHaar, Aug 07 '18 at 08:16
Yes this is perfectly valid code and will affect the object as long as `setPotential` actually does something to the object that is — Popeye, Aug 07 '18 at 08:16
If by "original object" you refer to the object for which the `updateAccountPotential` was called, `this.calculatePotential(accModel)` will probably **not** modify that object, since it is likely to modify just the `AccountModel ` instance. — Eran, Aug 07 '18 at 08:19
You could just check it through `accModel.getPotential()` after line `this.calculatePotential(accModel);` rather than asking — Shubhendu Pramanik, Aug 07 '18 at 08:19

score 1 · Accepted Answer · answered Aug 07 '18 at 08:18

Yes, assuming setPotential is a typical setter, because the value passed into updateAccountPotential is a reference to the object. That method modifies the object's state (via setPotential) (presumably). It's exactly as though you did this:

AccountModel a = /*...get the account model...*/;
AccountModel b = a;
b.setPotential(/*...*/);
// Both `b` and `a` refer to the same object, and so the state of that object
// is visible whether you go through `b` or `a` to get to it

Will the original object be affected by this code?

1 Answers1