Help with code for System.currentTimeMillis()

Question

I need to time how long it takes to do various sorts (selection sort, insertion sort) and was instructed to use System.currentTimeMillis() to accomplish this. Please take a look at the code below and let me know what is wrong. I can get the file to complile but it does not record the time it takes to run the sorts. I'm pretty sure my error is in the below section of code. In order to save space, I've only pasted the snippit of code for this particular function. Let me know if I need to paste more code. Thanks in advance.
case 5:
                         System.out.print("Enter the value to look for: ");
     val = scan.nextInt();
     time1 = System.currentTimeMillis();
     loc = list.linearSearch(val);
     time2 = System.currentTimeMillis();
                         totalTime = time1 - time2;
                         System.out.println("Total time for this search is: " + totalTime);
     if (loc != -1)
                              System.out.println("Found at location " + loc);
     else
                              System.out.println("Not in list");
     break;
                         

Answer 1

It could be that it isn't actually doing anything
though. Either because the data is poorly choosen or
because it isn't actually sorting due to a bug.The name of the method being timed is "linearSearch". That's a really poor name for a method that is supposed to be sorting. But from other aspects of the code I would guess that it is doing a linear search of an array, looking for a particular integer. Even if the integer isn't in the array, comparing 20,000 integers is a trivial exercise.
People don't realize just how long a millisecond is for a computer. If you have a 1 GB processor (not uncommon these days) then you can do one billion (one thousand million) operations per second. That's one million operations per millisecond. So chances are, even realizing that there's a whole lot of overhead in a high-level language, the OP's code runs in less than 1 millisecond.