RFR: 5108778 Too many instances of java.lang.Boolean created in Java application(core-libs) (original) (raw)

Stuart Marks stuart.marks at oracle.com
Fri Oct 9 18:58:08 UTC 2015

On 10/9/15 4:16 AM, Aleksey Shipilev wrote:

Please note that "static final Boolean myBool = new Boolean(true).booleanValue()" is a spec-recommended way to avoid binary incompatibilities caused by conditional compilation. See JLS 13.4.9. Therefore, deprecating Boolean constructors is a spec issue as well.

Well, not "recommended" :-) but point well taken. From JLS 13.4.9:

We note, but do not recommend, that if a field of primitive type of an interface may change, its value may be expressed idiomatically as in: boolean debug = new Boolean(true).booleanValue();

The bit about conditional compilation is with regard to constant expressions. The goal here is to get a boolean value into the initializer of a field, but to have that initializer not be a constant expression. I think that

 Boolean.valueOf(true).booleanValue()

would be sufficient for this and avoids using the constructor.

I'll file a bug on the JLS for this.

Thanks!

s'marks

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