In case of MIB's there may be 2 types of MIB OID's are possible
1) Scalar 2) Tabular
I hope you have enough knowledge about these & you can refer below code for reference
public class Mib implements MOGroup {
String sysDescr = client.getAsString(new OID(".1.3.6.1.2.1.1.1.0"));
}
And for and for more details have a look at "http://shivasoft.in/blog/java/snmp/create-snmp-client-in-java-using-snmp4j/".