Re: String.equals optimisation

[Per Bothner]

Stephen Crawley wrote:
> address@hidden said:
>
> > I'd be interested to hear of other reasons for Java's requirement to
> > intern all literal strings and constants. 
>
> Backwards compatibility.
>
> At this point we can only conjecture as to why Java was originally defined 
> this way.  My guess is that this decision was made in the early days when
> the language was being targeted at embedded computing and machines with
> not a lot of memory.  Having the JVM do interning of literals could save
> enough memory to matter.

Er, no.

String literals in JDK 1.0 were *not* interned.
That was changed in JDK 1.1.

> The world has moved on, and nobody thinks much about conserving string 
> space these days.

I don't believe saving space was the motivation, but consistency.
Assume:

static String x = "a";
static String y = "a";

Then you had (x==y) if x and y were defined in the same class, but
(x!=y) in they were defined in different classes.

People expect that ("a"=="a").
--
        --Per Bothner
address@hidden   http://per.bothner.com/