Concurrency - Java: How to Program Early Objects - page 1025

to stop the computation before it completes. Line 91 executes the PrimeCalculator to
begin finding primes. If the user clicks the cancelJButton , the event handler registered at
lines 107-115 calls PrimeCalculator 's method cancel (line 112), which is inherited from
class SwingWorker , and the calculation returns early. The argument true to method
cancel indicates that the thread performing the task should be interrupted in an attempt
to cancel the task.

23.12 sort / parallelSort Timings with the Java SE 8
Date/Time API
In Section 7.15, we used class Arrays 's static method sort to sort an array and we in-
troduced static method parallelSort for sorting large arrays more efficiently on multi-
core systems. Figure 23.28 uses both methods to sort 15,000,000 element arrays of ran-
dom int values so that we can demonstrate parallelSort 's performance improvement of
over sort on a multi-core system (we ran this on a dual-core system).

1

// SortComparison.java

2

// Comparing performance of Arrays methods sort and parallelSort.

3

import java.time.Duration;

4 import java.time.Instant;

5 import java.text.NumberFormat;

6 import java.util.Arrays;

7 import java.security.SecureRandom;

8
9 public class SortComparison

10 {

11 public static void main(String[] args)

12 {

13 SecureRandom random = new SecureRandom();

14
15 // create array of random ints, then copy it

16 int [] array1 = random.ints( 15_000_000 ).toArray();

17 int [] array2 = new int [array1.length];

18 System.arraycopy(array1, 0 , array2, 0 , array1.length);

19
20 // time the sorting of array1 with Arrays method sort

21 System.out.println( "Starting sort" );

22 Instant sortStart = Instant.now();

Arrays.sort(array1);
Instant sortEnd = Instant.now();

23

24

25
26 // display timing results

27 long sortTime = Duration.between(sortStart, sortEnd).toMillis();

28 System.out.printf( "Total time in milliseconds: %d%n%n" , sortTime);

29
30 // time the sorting of array2 with Arrays method parallelSort

31 System.out.println( "Starting parallelSort" );

32 Instant parallelSortStart = Instant.now();

Fig. 23.28 | Comparing performance of Arrays methods sort and parallelSort . (Part 1 of 2.)