JVM.dll crash in 1.4.2_07

Question

hi,
Platform : windows 2000 server
JVM: 1.4.2_07
Once in a while my program is crashing. The code is a C++ program that invokes Java methods via JNI. However, at the time of the crash, it is not making any JNI calls.
The crash dump shows the following stack for the thread in question:
Exception number: c0000005 (access violation)
0x113fc07
jvm!JVM_RegisterUnsafeMethods+0x6fc2
jvm!JVM_RegisterUnsafeMethods+0x716a
jvm!JVM_RegisterUnsafeMethods+0x6ed3
msvcrt+0x2b530
kernel32!BaseThreadStart+0x34
I guess my question is - when is JVM_RegisterUnsafeMethods called by the JVM? And what would cause it to crash.
Thanks.
Ash

Answer 1

You need to actually write your own FocusTraversalPolicy class.
It's actually pretty easy - just subclass FocusTraversalPolicy and override all the methods. You need to have your own algorithm for determining the next/first/last/etc components and after a short look at your code my guess would be to hold a reference to each component on your form in an array in the order you want the focus to move in and then you can easily return the "next" or "previous" component by looking up the array.
Some of the methods can call others - e.g. getDefaultComponent, getFirstComponent, and getInitialComponent usually all return the same value.
Regards,
Tim