hi guys,
i wonna to code simple program that could control the system threads in the system by block or
start a new job, how to do this in java, or from where i can start to acheive this.

What system threads are u talking about, please elaborate.

i mean how to view the whole running system threads

As far as blocking system threads are concerned, I am sure its not possible, for:
Every Java application executes within its own JVM boundaries, and is not allowed to intervene in processing of threads executing in outer world (Security reasons, and very correctly done. Otherwise people wanting to block system threads may end up destroying everything on servers :icon_wink: ).

For fetching information on executing System threads/Processes, here's a good read: