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From: Eric Sosman <esosman@comcast-dot-net.invalid>
Newsgroups: comp.lang.java.programmer
Subject: Re: Java blunders
Date: Mon, 28 Jul 2014 16:39:27 -0400
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On 7/28/2014 4:23 PM, Josip Almasi wrote:
> On 07/24/2014 03:53 AM, Roedy Green wrote:
>> On Wed, 23 Jul 2014 19:55:09 -0400, Arne Vajhøj <arne@vajhoej.dk>
>> wrote, quoted or indirectly quoted someone who said :
>>
>>> But is it a problem in real world programming?
>>>
>>> I have never seen a problem due to this.
>>
>>
>> The most common error is like this:
>>
>> out.println ( "the answer is " +
>> a + b
>> + ".");
>>
>> you must write that as:
>>
>> out.println ( "the answer is " + (a + b) + ".");
>
> I think you guys missed worst thing with java concatenation, and it's
> got nothing to do with operator.
> It's about how operator gets interpreted:
>
> out.println ( new StringBuffer("the answer is ").append(new
> StringBuffer(a + b)).append(new StringBuffer("."));

     Why do you think this is so?  javac 1.8.0_11 compiles it to
the equivalent of

	out.println(new StringBuilder()
	    .append("the answer is ")
	    .append(a + b)
	    .append(".")
	    .toString());

... and I think all javac's have done so for a long time (but I
don't have them available for checking).

> It's three new objects, all synchronized.

     ... for suitable values of "three" (i.e., 2) and "all" (0).

> OK I haven't read the spec for a while but that's it IIRC, spec requires
> it that way.

     StringBuilder replaced StringBuffer for this purpose in Java 1.5,
just under ten years ago.  I guess that counts as "a while."  ;-)

> And if you want to avoid the garbage, you need to
>
> StringBuilder shit = new StringBuilder();
> shit.append("the answer is ");
> shit.append(a + b);
> shit.append(".");
> and another line to get the string.

     Um, er, no.

-- 
esosman@comcast-dot-net.invalid