check java version at solaris bit suported version

java -version
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05)
Java HotSpot(TM) Server VM (build 1.5.0_06-b05, mixed mode)

if you see Server VM it means it is 64bit and if you see  Client

Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_16-b02)
Java HotSpot(TM) Client VM (build 1.5.0_16-b02, mixed mode, sharing)


to see if it support 64 run this command

java -d64 -version
java version "1.5.0_34"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_34-b03)
Java HotSpot(TM) 64-Bit Server VM (build 1.5.0_34-b03, mixed mode)

to see more clear message

run
truss -t exec java -d64 -version
java version "1.5.0_34"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_34-b03)
Java HotSpot(TM) 64-Bit Server VM (build 1.5.0_34-b03, mixed mode)