StopWatch.java.html

  1  /**
  2     A stopwatch accumulates time when it is running. You can 
  3     repeatedly start and stop the stopwatch. You can use a
  4     stopwatch to measure the running time of a program.
  5  */
  6  public class StopWatch
  7  {  
  8     private long elapsedTime;
  9     private long startTime;
 10     private boolean isRunning;
 11  
 12     /**
 13        Constructs a stopwatch that is in the stopped state
 14        and has no time accumulated.
 15     */
 16     public StopWatch()
 17     {  
 18        reset();
 19     }
 20  
 21     /**
 22        Starts the stopwatch. Time starts accumulating now.
 23     */
 24     public void start()
 25     {  
 26        if (isRunning) { return; }
 27        isRunning = true;
 28        startTime = System.currentTimeMillis();
 29     }
 30     
 31     /**
 32        Stops the stopwatch. Time stops accumulating and is
 33        is added to the elapsed time.
 34     */
 35     public void stop()
 36     {  
 37        if (!isRunning) { return; }
 38        isRunning = false;
 39        long endTime = System.currentTimeMillis();
 40        elapsedTime = elapsedTime + endTime - startTime;
 41     }
 42     
 43     /**
 44        Returns the total elapsed time.
 45        @return the total elapsed time
 46     */
 47     public long getElapsedTime()
 48     {  
 49        if (isRunning) 
 50        {  
 51           long endTime = System.currentTimeMillis();
 52           return elapsedTime + endTime - startTime;
 53        }
 54        else
 55        {
 56           return elapsedTime;
 57        }
 58     }
 59     
 60     /**
 61        Stops the watch and resets the elapsed time to 0.
 62     */
 63     public void reset()
 64     {  
 65        elapsedTime = 0;
 66        isRunning = false;
 67     }
 68  }