This tip is for when you want to place an action after a time gap between two occurrences (for example, to invalidate an unused session after some permitted time, or to note the total time use of a resource). Instead of storing the starting time of the first occurrence (event) and the ending time of next occurrence (event) as in block A, follow the procedure shown in block B.
//block ADate start = new Date();//after some thingDate end = new Date();//Do some thing with start and end to find the time difference //block Blong start = System.currentTimeMills();//after some thinglong end = System.currentTimeMills();long timeUsed = end - start;//do something with timeUsed
The technique shown in block B avoids the unnecessary creation and garbage collection of two Objects, hence increasing performance.