When I run the ps -ef command I receive something like this:
root 26728 26725 99 Sep25 ? 1184018564-02:43:14 java -jar /root/TaskManager.jar
I need to understand why the time is shown like this "1184018564-02:43:14"
So your Java process has been running for 1184018564 CPU days (about 3,243,886 CPU years), OR ... something bad has happened.
It is Ubuntu bug #859311 associated with long-running multi-threaded processes.
The UNIX time format is internally represented as a numeric value indicating the number of seconds since 1/1/1970.