eclipse - Exception in thread "main" java.lang.NoClassDefFoundError: com/mongodb/operation/OperationExecutor -

i had mongodb java driver , maven. cannot find out probelm is. can help, thank you?

the eclipse ide show error, didnot insert,find functions:

exception in thread "main" java.lang.noclassdeffounderror: com/mongodb/operation/operationexecutor detail reason showing this: mongoclient mongoclient = new mongoclient( db_host , 27017 );