Immutable objects with Mutable fields

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The Setup: I am attempting to write a value object, so I figured it would be best to make it immutable. This object has a BigDecimal, so:

public class MyValueObject {
    private final BigDecimal bob;

    public MyValueObject() {
        bob = new BigDecimal(0);
    }
}

I have also written a handful of methods, including an add method, that return new MyValueObjects. Here is an example of one:

public MyValueObject add(BigDecimal augend) {
        return new MyValueObject(this.bob.add(augend);
}

The question is, does this effectively set bob or is it returning a completely new MyValueObject with an entirely new BigDecimal as expected?

asked 2 mins ago

nihilon

54

1 Answer

Vote count:

0

If you use "new", you are creating a new object. So It is returning a completely new MyValueObject which utilizes "bob", but is not the same.

answered 41 secs ago

La-comadreja

3,386

Immutable objects with Mutable fields