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Groups > comp.lang.java.programmer > #8464

Re: Avoid creating a stacktrace prior to JDK 1.7

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On 10/1/2011 4:04 PM, Jan Burse wrote:
> Lew schrieb:
>> - Rules were made to be broken.
>
> Yes, a well known common place.
>
> Now back to the original question of my
> post, I was giving the ClassNotFoundException
> only as a motivation, can I suppress the
> fetching of the backtrace in a Java
> Exception object prior to JDK 1.7?

     Quoth the Java SE 6 Javadoc: "A throwable [sic] contains a
snapshot of the execution stack of its thread at the time it was
created."  That is, the Javadoc promises that a Throwable carries
a stack trace.  A Throwable with no stack trace breaches the
promise, and since that promise was still in force as of 1.6 I
deduce that there's no such thing as a stackless Throwable in that
version, or that it's a bug if there is.

     However, it's the trace of the stack that *creates* the
Throwable, not necessarily that of the stack that *throws* it.
So you could create a Throwable once and throw it as many times
from as many different contexts as you like:

	class MasochismInAction {
	    private static OriginUnknownException mystery =
	        new OriginUnknownException("Ha-ha, can't find me!");
	    public void foolMeOnce() throws OriginUnknownException {
	        if (iFeelLikeIt) {
	            throw mystery;
	        }
	    }
	    public void foolMeTwice() throws OriginUnknownException {
	        if (Math.random() < 0.3) {
	            throw mystery;
	        }
	    }
	    ...
	}

... and there you have it: Exceptions without (most of) the expense
of filling a stack trace.  Also, it must be noted, Exceptions with
less ability to help in debugging than almost any others.  ("Almost"
because I've heard somewhere that the JVM creates a few Throwables
like VirtualMachineError in advance, because by the time they're
needed the JVM can no longer trust itself to fill them in properly.)

     Personally, I think "Don't Do That" is sage advice here.

-- 
Eric Sosman
esosman@ieee-dot-org.invalid

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Avoid creating a stacktrace prior to JDK 1.7 Jan Burse <janburse@fastmail.fm> - 2011-09-30 15:57 +0200
  Re: Avoid creating a stacktrace prior to JDK 1.7 Stanimir Stamenkov <s7an10@netscape.net> - 2011-10-01 13:27 +0300
    Re: Avoid creating a stacktrace prior to JDK 1.7 Jan Burse <janburse@fastmail.fm> - 2011-10-01 13:22 +0200
      Re: Avoid creating a stacktrace prior to JDK 1.7 Lew <lewbloch@gmail.com> - 2011-10-01 09:10 -0700
        Re: Avoid creating a stacktrace prior to JDK 1.7 Stanimir Stamenkov <s7an10@netscape.net> - 2011-10-01 20:31 +0300
        Re: Avoid creating a stacktrace prior to JDK 1.7 Jan Burse <janburse@fastmail.fm> - 2011-10-01 20:02 +0200
          Re: Avoid creating a stacktrace prior to JDK 1.7 Lew <lewbloch@gmail.com> - 2011-10-01 12:21 -0700
            Re: Avoid creating a stacktrace prior to JDK 1.7 Jan Burse <janburse@fastmail.fm> - 2011-10-01 22:04 +0200
              Re: Avoid creating a stacktrace prior to JDK 1.7 Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-10-01 16:24 -0400
                Re: Avoid creating a stacktrace prior to JDK 1.7 Jan Burse <janburse@fastmail.fm> - 2011-10-01 23:14 +0200
                Re: Avoid creating a stacktrace prior to JDK 1.7 Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-10-01 17:28 -0400
                Re: Avoid creating a stacktrace prior to JDK 1.7 Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-10-01 23:45 +0000
                Re: Avoid creating a stacktrace prior to JDK 1.7 Stanimir Stamenkov <s7an10@netscape.net> - 2011-10-02 00:58 +0300
                Re: Avoid creating a stacktrace prior to JDK 1.7 Jan Burse <janburse@fastmail.fm> - 2011-10-02 02:04 +0200
                Re: Avoid creating a stacktrace prior to JDK 1.7 Lew <lewbloch@gmail.com> - 2011-10-01 20:06 -0700
                Re: Avoid creating a stacktrace prior to JDK 1.7 Stanimir Stamenkov <s7an10@netscape.net> - 2011-10-02 13:14 +0300
                Re: Avoid creating a stacktrace prior to JDK 1.7 Lew <lewbloch@gmail.com> - 2011-10-02 08:37 -0700
                Re: Avoid creating a stacktrace prior to JDK 1.7 Jan Burse <janburse@fastmail.fm> - 2011-10-02 20:26 +0200
                Re: Avoid creating a stacktrace prior to JDK 1.7 Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-10-02 17:51 -0400
                Re: Avoid creating a stacktrace prior to JDK 1.7 Jan Burse <janburse@fastmail.fm> - 2011-10-03 01:32 +0200
    Re: Avoid creating a stacktrace prior to JDK 1.7 Stanimir Stamenkov <s7an10@netscape.net> - 2011-10-01 20:19 +0300
      Re: Avoid creating a stacktrace prior to JDK 1.7 Jan Burse <janburse@fastmail.fm> - 2011-10-01 20:04 +0200
        Re: Avoid creating a stacktrace prior to JDK 1.7 Stanimir Stamenkov <s7an10@netscape.net> - 2011-10-01 21:15 +0300

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