Date: Mon, 28 Apr 2003 09:16:54 -0700 (PDT)
From: Ross Knippel <###@###.###>
Subject: Re: Exception Report Question
To: ###@###.###
Cc: ###@###.###
MIME-Version: 1.0
Content-MD5: KZ6yLhm3HKNV4SyAApm1sA==

Yes, the printed array index seems incorrect when
the method is compiled by the latest 1.2.2_15.
It looks okay when interpreted.

-ross

---- OutOfBounds.java -------------

class DLinkNode {
  DLinkNode next;
  Object element;
  int field;
  DLinkNode() {}
}

class OutOfBounds {
  static DLinkNode anchor;
  static int elementCount;

  public Object[] toNativeArray ()
  {
    Object[] array = new Object[elementCount];
    DLinkNode node = anchor.next;
    int idx = 0;
    // loop until end of list
    while (node != anchor)
      {
System.out.println("idx: "+idx+" field: "+node.field);
array[idx++] = node.element;
node = node.next;
      }
    return array;
  }
  
  public static void main(String[] args) {
    int allocCount = 100;
    DLinkNode last = null;
    anchor = last;
    for(int i = allocCount - 1; i >= 0 ; i--) {
      DLinkNode n = new DLinkNode();
      if (last == null) last = n;
      n.next = anchor;
      n.field = i;
      anchor = n;
    }
    last.next = anchor;
    elementCount = allocCount - 2; // force indexOutOfBounds
    System.out.println("Init done.");
    Object[] oa = new OutOfBounds().toNativeArray();
  }
}

> /files/ws/evm/build/solaris/bin/java OutOfBounds

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0 <-----
        at OutOfBounds.toNativeArray(Compiled Code)
        at OutOfBounds.main(Compiled Code)
        
> /files/ws/evm/build/solaris/bin/java -Djava.compiler=NONE OutOfBounds

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 98 <-----
        at OutOfBounds.toNativeArray(OutOfBounds.java:21)
        at OutOfBounds.main(OutOfBounds.java:41)

> From: "Keith Melkild" <###@###.###>
> To: ###@###.###
> Subject: Exception Report Question
> Date: Sat, 26 Apr 2003 18:33:30 -0500
> MIME-Version: 1.0
>
> Hi,
>
> We are seeing this error periodically in 1.2.2 and I was wondering if anyone
> could shed some light on this. This method is out of a DList collection
> class that we wrote quite some time ago. Here's the question? How can the
> method below be trying to access the element specified? It doesn't seem
> possible. Yes, we could have the structure screwed up and flip the int, but
> I would think this would result in the smallest negative number
> (-2147483648) being reported. Could the element # being reported be bogus?
>
> Thanks,
> Keith
>
>
> java.lang.ArrayIndexOutOfBoundsException: -810172480
> at com.nortelnetworks.ims.foundation.collection.DList.toNativeArray(Compiled
> Code)
> at
> com.nortelnetworks.ims.mw.imdb.tables.IMWatchersTable.querySvcPkgWatchers(Co
> mpiled Code)
> public Object[] toNativeArray ()
> {
> Object[] array = new Object[elementCount];
> DLinkNode node = anchor.next;
> int idx = 0;
> // loop until end of list
> while (node != anchor)
> {
> array[idx++] = node.element;
> node = node.next;
> }
> return array;
> }
>