1

I am working on implementing a simulated annealing program and part of this involves calculating scores from a .txt file that my java program reads.

1) an input string is read from the user. The longer my input string, the more likely the following exception below occurs

2) the score that is calculated is essentially adding a lot of decimal numbers and I store it in a 'double' variable.

Can someone please advise me why such an exception would occur?

Score from Hill Swap: 0.24874990000000005 After swap... Exception in thread "main" java.lang.NumberFormatException: For input string: "7.92066E-" at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1224)

Thanks very much!

Roy
  • 763
  • 2
  • 8
  • 18
  • Doubles have rounding errors (just try `0.01 + 0.09`: it's not `0.1`). That makes doubles unsuitable for scientific or financial calculations. [Drools Planner](http://www.jboss.org/drools/drools-planner)'s simulated annealing supports using alternative Score implementations, such as a `BigDecimal` (which doesn't have rounding errors but is slower). – Geoffrey De Smet Apr 28 '11 at 09:36

1 Answers1

7

It means that your program is trying to parse the string "7.92066E-" which is not parseable as a Double.

You should check where this string is coming from (the rest of the stack trace should tell you) and make sure that you're not getting invalid data somewhere along the line.

Cameron Skinner
  • 51,692
  • 2
  • 65
  • 86
  • 2
    Its not valid because you are missing a number after the E. It should be something like 7.92066E042- – James Anderson Apr 28 '11 at 01:56
  • thanks very much, your answers are indeed right, there are numbers in my data file of the type 7.92066E-5. this is causing the problem as i'm stopping the read prematurely. problem will now be fixed. Thanks! – Roy Apr 28 '11 at 02:26