Java Reference
In-Depth Information
9
// class that stores two Instants in time
10
class
TimeData
11
{
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public
Instant start;
13
public
Instant end;
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// return total time in seconds
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public double
timeInSeconds()
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{
18
return
Duration.between(start, end).toMillis() /
1000.0
;
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}
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}
// end class TimeData
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22
public class
FibonacciDemo
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{
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public static void
main(String[] args)
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throws
InterruptedException, ExecutionException
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{
27
// perform synchronous fibonacci(45) and fibonacci(44) calculations
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System.out.println(
"Synchronous Long Running Calculations"
);
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TimeData synchronousResult1 = startFibonacci(45);
TimeData synchronousResult2 = startFibonacci(44);
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double
synchronousTime =
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calculateTime(synchronousResult1, synchronousResult2);
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System.out.printf(
34
" Total calculation time = %.3f seconds%n"
, synchronousTime);
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// perform asynchronous fibonacci(45) and fibonacci(44) calculations
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System.out.printf(
"%nAsynchronous Long Running Calculations%n"
);
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CompletableFuture<TimeData> futureResult1 =
CompletableFuture.supplyAsync(() -> startFibonacci(
45
));
CompletableFuture<TimeData> futureResult2 =
CompletableFuture.supplyAsync(() -> startFibonacci(
44
));
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40
41
42
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// wait for results from the asynchronous operations
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TimeData asynchronousResult1 = futureResult1.get();
TimeData asynchronousResult2 = futureResult2.get();
45
46
double
asynchronousTime =
47
calculateTime(asynchronousResult1, asynchronousResult2);
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System.out.printf(
49
" Total calculation time = %.3f seconds%n"
, asynchronousTime);
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// display time difference as a percentage
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String percentage = NumberFormat.getPercentInstance().format(
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synchronousTime / asynchronousTime);
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System.out.printf(
"%nSynchronous calculations took %s"
+
55
" more time than the asynchronous calculations%n"
, percentage);
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}
57
58
// executes function fibonacci asynchronously
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private static
TimeData startFibonacci(
int
n)
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{
Fig. 23.30
|
Fibonacci calculations performed synchronously and asynchronously. (Part 2 of 4.)
