Java process reports "incorrect" number of available processors

Question

I'm running a Java 1.6 process on an 8-node NUMA machine using:

numactl --cpunodebind=0 java -server com.foo.Bar

Each node has 8 CPUs as reported by numactl --hardware:

available: 8 nodes (0-7)
node 0 cpus: 1 2 3 4 5 6 7 8
node 0 size: ...
node 0 free: ...
node 1 cpus: 9 10 11 12 13 14 15 16
node 1 size: ...
node 1 free: ...
...
node 7 cpus: 56 57 58 59 60 61 62 63
node 7 size: ...
node 7 free: ...

The function call Runtime.getRuntime().availableProcessors() returns 64.

Why does the Runtime object for the process report 64 available processors, despite the cpunodebind restriction? Is there a way to get the actual number of processors available to the Java process?