For SNMP application development with Java, please download the SNMP4J sources and library.
The SNMP4J Command Line Tool (CLT) can be used to send SNMPv1/v2c/v3 requests and traps to a target using UDP or TCP transport using IPv4 and IPv6 (if available on the used platform). The tool supports SNMPv3 MD5 and SHA authentication as well as DES (CBC), 3DES (EDE), AES128, AES192, and AES256 encryption.
Add MIB support to SNMP4J using SNMP4J-SMI without changing your existing SNMP4J code. Basically three additional lines of code will do the trick! See the SNMP4J-SMI JavaDoc for the details.
SNMP4J and the SNMP4J-Agent sources and binaries are freely available under the Apache 2.0 license. SNMP4J-AgentX as well as SNMP4J-AgentJMX are released under the GNU Public License version 2 and a commercial license which can be purchased online.