Java 8 introduced a new method called as parallelSort() in java.util.Arrays Class. It uses Parallel Sorting of array elements
Algorithm of parallelSort()
1. The array is divided into sub-arrays and that sub-arrays is again divided into their sub-arrays, until the minimum level of detail in a set of array. 2. Arrays are sorted individually by multiple thread. 3. The parallel sort uses Fork/Join Concept for sorting. 4. Sorted sub-arrays are then merged.
Syntax :
-
For sorting data in ascending order :
public static void parallelSort(Object obj[])
-
For sorting data in specified range in ascending order :
public static void parallelSort(Object obj[], int from, int to)
Advantage :
parallelSort() method uses concept of MultiThreading which makes the sorting faster as compared to normal sorting method.
Example
Below are the program that will illustrate the use of Arrays.parallelSort():
Program 1: To demonstrate use of Parallel Sort
// Java program to demonstrate // Arrays.parallelSort() method import java.util.Arrays;
public class ParallelSort {
public static void main(String[] args)
{
// Creating an array
int numbers[] = { 9 , 8 , 7 , 6 , 3 , 1 };
// Printing unsorted Array
System.out.print( "Unsorted Array: " );
// Iterating the Elements using stream
Arrays.stream(numbers)
.forEach(n -> System.out.print(n + " " ));
System.out.println();
// Using Arrays.parallelSort()
Arrays.parallelSort(numbers);
// Printing sorted Array
System.out.print( "Sorted Array: " );
// Iterating the Elements using stream
Arrays.stream(numbers)
.forEach(n -> System.out.print(n + " " ));
}
} |
Unsorted Array: 9 8 7 6 3 1 Sorted Array: 1 3 6 7 8 9
Time Complexity is O(nlogn)
Program 2: To demonstrate use of Parallel Sort w.r.t. Series Sort (Normal Sort)
// Java program to demonstrate impact // of Parallel Sort vs Serial Sort import java.util.Arrays;
import java.util.Random;
public class ParallelSort {
public static void main(String[] args)
{
// Creating an array
int numbers[] = new int [ 100 ];
// Iterating Loop till i = 1000
// with interval of 10
for ( int i = 0 ; i < 1000 ; i += 10 ) {
System.out.println( "\nFor iteration number: "
+ (i / 10 + 1 ));
// Random Int Array Generation
Random rand = new Random();
for ( int j = 0 ; j < 100 ; j++) {
numbers[j] = rand.nextInt();
}
// Start and End Time of Arrays.sort()
long startTime = System.nanoTime();
// Performing Serial Sort
Arrays.sort(numbers);
long endTime = System.nanoTime();
// Printing result of Serial Sort
System.out.println( "Start and End Time in Serial (in ns): "
+ startTime + ":" + endTime);
System.out.println( "Time taken by Serial Sort(in ns): "
+ (endTime - startTime));
// Start and End Time of Arrays.parallelSort()
startTime = System.nanoTime();
// Performing Parallel Sort
Arrays.parallelSort(numbers);
endTime = System.nanoTime();
// Printing result of Parallel Sort
System.out.println( "Start and End Time in parallel (in ns): "
+ startTime + ":" + endTime);
System.out.println( "Time taken by Parallel Sort(in ns): "
+ (endTime - startTime));
System.out.println();
}
}
} |
For iteration number: 1 Start and End Time in Serial (in ns): 3951000637977:3951000870361 Time taken by Serial Sort(in ns): 232384 Start and End Time in parallel (in ns): 3951000960823:3951000971044 Time taken by Parallel Sort(in ns): 10221 For iteration number: 2 Start and End Time in Serial (in ns): 3951001142284:3951001201757 Time taken by Serial Sort(in ns): 59473 Start and End Time in parallel (in ns): 3951001256643:3951001264039 Time taken by Parallel Sort(in ns): 7396 . . . For iteration number: 99 Start and End Time in Serial (in ns): 3951050723541:3951050731520 Time taken by Serial Sort(in ns): 7979 Start and End Time in parallel (in ns): 3951050754238:3951050756130 Time taken by Parallel Sort(in ns): 1892 For iteration number: 100 Start and End Time in Serial (in ns): 3951050798392:3951050804741 Time taken by Serial Sort(in ns): 6349 Start and End Time in parallel (in ns): 3951050828544:3951050830582 Time taken by Parallel Sort(in ns): 2038
Note : Different time intervals will be printed But parallel sort will be done before normal sort.
Environment: 2.6 GHz Intel Core i7, java version 8