Re: Re: Re: Re: Memory Use/Garbage Collection: Java vs Perl

[hossman]

this whole thread is pretty OT, so i won't let that stop me from pointing out...

You aren't garunteed to get the behavior you are seeing from every implimentation of Java -- the JLS only requires that string concatination must be implimented using a StringBuffer, not that multiple string concatenations must be optimized into a single StringBuffer.

ie...

this...

    String foo = "bar" + "baz";

is garunteed to be equivilent to this...

    StringBuffer tmp = new StringBuffer("bar");
    tmp.append("baz");
    String foo = tmp.toString();

But this...

    String wb = "yakko" + "wakko" + "dot";

might be implimented as...

    StringBuffer tmp1 = new StringBuffer("yakko");
    tmp1.append("wakko");
    String tmp2 = tmp1.toString();
    StringBuffer tmp3 = new StringBuffer(tmp2);
    tmp3.append("dot");
    String wb = tmp3.toString();

You might want to check out JDC TechTip 2002-03-05 particularly it's discussion of "a statement found in the Java Language Specification section 15.18.1.2"