Java program execution time

The first type is measured in milliseconds.
JavaCode
// Pseudocode
Long starttime = system. currenttimemillis (); // get the start time
Dosomething (); // code snippet for testing
Long endtime = system. currenttimemillis (); // get the end time
System. Out. println ("ProgramRunning time: "+ (end-Start) +" Ms ");

The second type is calculated in nanoseconds.
Java code
// Pseudocode
Long starttime = system. nanotime (); // get the start time
Dosomething (); // code snippet for testing
Long endtime = system. nanotime (); // get the end time
System. Out. println ("program running time:" + (end-Start) + "ns ");