Bug in ArrayList.toArray() method?

From: Keith McLeod (KeithMcLeod_at_discussions.microsoft.com)
Date: 02/18/05

  • Next message: Bob: "Re: Paint a graph" 
    Date: Fri, 18 Feb 2005 07:51:04 -0800

    We are writing a GIS application in C# and using Vivid Solutions’ Java
    Topology Suite converted to J# for our Computational Geometry library. I am
    receiving a null reference exception on the following line of code…

    object [] list = spatialIndex.query(new Envelope( minX + (ix * tileWidth),
    minX + ((ix + 1) * tileWidth), maxY - (iy * tileHeight), maxY - ((iy + 1) *
    tileHeight))).toArray();

    This is the method being called…
    protected List query(Object searchBounds) {
        if (!built) { build(); }
        ArrayList matches = new ArrayList();
        if (itemBoundables.isEmpty()) {
          Assert.isTrue(root.getBounds() == null);
          return matches;
        }
        if (getIntersectsOp().intersects(root.getBounds(), searchBounds)) {
          query(searchBounds, root, matches);
        }
        return matches;
    }

    I’ve stepped through the code and get all the way to the second "return
    matches" statement. The matches object is indeed instantiated and has objects
    (in this case they are ints) in it so it is definitely not null. This method
    is used throughout the rest of the application and works fine. It just seems
    to be the toArray method that is giving us a problem. I’m wondering if this
    is a known bug in the J# runtime. We are using the J# redistributable package
    1.1 along with the J# supplemental UI library.

    One more bit of information, if I step through this code more than twice,
    the exception then becomes a System.EngineException and I have to reboot my
    computer.

    Thank you in advance for any information you can provide regarding this issue.

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