Java News from Sunday, September 12, 2004

Martin Fowler points out some really weird behavior in JUnit. Apparently JUnit creates a new test object for each test. I understand why it does that, and I agree with the principles behind it. But this has some other implications:

• If this is the case why bother with a setUp() method? Why not just use the constructor? tearDown() makes a tad more sense, but not much; and I've never actually needed to use it in practice.
• If something's going to take a long time to set up, you should make it a local variable in every test that uses it, rather than a field, as long as some tests don't use it.

Several people have now tried to explain this to me, including Bill Venners, and it still doesn't make a lot of sense. The only real difference appears to be that the constructor is called before any tests are run and the setUp method is called immediately before each test is run. I suppose if the fixture did something like iopen a file for writing that only one object could do at a time you might have to use setUp but barring that there's not a whole lot of reason to use setUp.

SpaceRoots has released Mantissa 5.3, "a collection of various mathematical tools aimed towards for simulation. It is not a complete mathematical library like GSL, NAG or IMSL, but it contains various algorithms useful for dynamics simulation and 3D geometry computation." Its algorithms inlcude:

• a small set of linear algebra classes
• a least squares estimator
• some curve fitting classes
• several ordinary differentials equations integrators, either with fixed steps or adaptive stepsize control (see below)
• vectors and rotations in a three dimensional space
• algebra-related classes like rational and double polynomials
• various orthogonal polynomials:
  • Chebyshev
  • Hermite
  • Laguerre
  • Legendre
• some random numbers and vectors generation classes:
  • Robert M. Ziff four tap shift register (contributed by Bill Maier)
  • Makoto Matsumoto and Takuji Nishimura Mersenne twister
  • generators for vectors with correlated components
• some basic (min, max, mean, standard deviation) statistical analysis classes
• some optimization algorithms using direct search methods:
  • the Nelder-Mead simplex method
  • Virginia Torczon's multi-directional method

André Simon has released Highlight 2.2-3, a free-as-in-speech (GPL) source code formatter that understands 85 programming languages including Java and generates HTML, XHTML, RTF, TeX, LaTeX, and XSL-FO output. Highlight is a command line application written in C++ for Unix and Windows.

Frank Karlstrøm has posted the second beta of JCache 1.0, an open source caching system for Java database-based applications based on the JSR-107 JCache API. This is mostly a bug fix release. JCache is published under the LGPL.