Example of java computing program execution time

Many elaborate programs need to calculate the time consumed by one execution.
Or, we often test the time it takes to read data.

The code is as follows:

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System. currentTimeMillis () can read the current time in milliseconds. The value is the current time minus 0 minutes 0 seconds on the first day of January 1, 1970. Package com. javaer. examples;   Public class JavaTime {   Public static void main (String [] args ){ Long t1 = System. currentTimeMillis (); For (int I = 0; I <10000; I ++ ){ System. out. println (I + "I am 111cn.net ");   } Long t2 = System. currentTimeMillis (); Long t = t2-t1; System. out. println (t + "millisecond ");  }   } Output 9994 I am 111cn.net 9995 I am 111cn.net 9996 I am 111cn.net 9997 I am 111cn.net 9998 I am 111cn.net 9999 I am 111cn.net 125 ms

Example:

The code is as follows:

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/** * Main. java  * * @ Author 111cn.net */ Public class Main { /** * Calculate the number of milliseconds that have elapsed since the two time points.      * */ Public void computeAndDisplayElapsedTime (){ Long startTime = System. currentTimeMillis (); For (int I = 0; I <10; I ++ ){ Try { Thread. sleep (60 ); } Catch (InterruptedException ex ){ Ex. printStackTrace ();             }         } Long endTime = System. currentTimeMillis (); Float seconds = (endTime-startTime)/1000F; System. out. println (Float. toString (seconds) + "seconds .");     } /** * Start the program      * * @ Param args the command line arguments */ Public static void main (String [] args ){ New Main (). computeAndDisplayElapsedTime ();     } } The output result is similar: 0.609 seconds.

Example 3

The code is as follows:

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Package test; Import java. util .*; Public class Test2 { Public static void main (String [] args) { Long t1 = System. currentTimeMillis (); // Obtain the current time before sorting Try { Thread. currentThread (). sleep (3160 ); } Catch (Exception err) { } Long t2 = System. currentTimeMillis (); // Obtain the current time after sorting Calendar c = Calendar. getInstance (); C. setTimeInMillis (T2-T1 ); System. out. println ("time consumed:" + c. get (Calendar. MINUTE) + "points" + c. get (Calendar. SECOND) + "seconds" + c. get (Calendar. MILLISECOND) + "microsecond "); } }