I dont think there is any such java software. I dont think there exists any API for messaging access. But even if it exists, no programmer uses it since most java phones are not capable of multitasking and so you would have to keep the app running always and wont be able to do anything else(not on the E6 though. It supports multitasking).
Why dont you use SMS7.IN to schedule your sms'es?
You will have to go online though to post your messages and set the time for the delivery of the message.