Java 8 Arrays Parallel Prefix Example
August 23, 2016
BinaryOperator, IntBinaryOperator, DoubleBinaryOperator etc. Find the method details.
1.: It uses
BinaryOperator to update the array of objects.
void parallelPrefix(T[] array, BinaryOperator<T> op)
2.: Here we can pass from and to index.
void parallelPrefix(T[] array, int fromIndex, int toIndex, BinaryOperator<T> op)
3.: It update the array of primitive data types.
void parallelPrefix(int[] array, IntBinaryOperator op)
4.: Here we can pass from and to index.
void parallelPrefix(int[] array, int fromIndex, int toIndex, IntBinaryOperator op)
Arrays.parallelPrefix() are also used with other primitive data types such as long, float, double.
Arrays.parallelPrefix() with Array of Objects
ParallelPrefixDemo.java
package com.concretepage;
import java.util.Arrays;
import java.util.function.BinaryOperator;
import java.util.function.Consumer;
public class ParallelPrefixDemo {
public static void main(String[] args) {
BinaryOperator<Floor> opt = (f1, f2) -> new Floor(f1.getLength() + f2.getLength(),
f1.getWidth() + f2.getWidth());
Floor[] floors = Floor.getFloorSizes();
System.out.println("parallel prefix for complete array");
Arrays.parallelPrefix(floors, opt);
Consumer<Floor> print = f-> System.out.println(f.getLength()+", "+f.getWidth());
Arrays.stream(floors).forEach(print);
System.out.println("parallel prefix for array from index 1 to 4");
floors = Floor.getFloorSizes();
Arrays.parallelPrefix(floors, 1, 4, opt);
Arrays.stream(floors).forEach(print);
}
}
package com.concretepage;
public class Floor {
private int length;
private int width;
public Floor(int length, int width) {
this.length = length;
this.width = width;
}
public int getLength() {
return length;
}
public int getWidth() {
return width;
}
public static Floor[] getFloorSizes() {
Floor[] floors = new Floor[6];
floors[0] = new Floor(2, 3);
floors[1] = new Floor(4, 5);
floors[2] = new Floor(3, 6);
floors[3] = new Floor(2, 1);
floors[4] = new Floor(1, 7);
floors[5] = new Floor(4, 3);
return floors;
}
}
parallel prefix for complete array 2, 3 6, 8 9, 14 11, 15 12, 22 16, 25 parallel prefix for array from index 1 to 4 2, 3 4, 5 7, 11 9, 12 1, 7 4, 3
Arrays.parallelPrefix() with Array of Primitive Data Types
ParallelPrefixDemoWithPrimitiveData.java
package com.concretepage;
import java.util.Arrays;
import java.util.function.DoubleBinaryOperator;
import java.util.function.DoubleConsumer;
import java.util.function.IntBinaryOperator;
import java.util.function.IntConsumer;
public class ParallelPrefixDemoWithPrimitiveData {
public static void main(String[] args) {
int[] intNum1 = {3,4,2,5,1,6,3};
IntBinaryOperator intOpt = (i1, i2) -> i1 * i2;
System.out.println("parallel prefix for complete array");
Arrays.parallelPrefix(intNum1, intOpt);
IntConsumer intCon = i -> System.out.print(i+" ");
Arrays.stream(intNum1).forEach(intCon);
System.out.println("\nparallel prefix for array from index 1 to 4");
int[] intNum2 = {3,4,2,5,1,6,3};
Arrays.parallelPrefix(intNum2, 1, 4, intOpt);
Arrays.stream(intNum2).forEach(intCon);
double[] dbNum1 = {3.2,4.1,2.2,5.4,1.2,6.4,3.2};
DoubleBinaryOperator dbOpt = (d1, d2) -> d1 + d2;
System.out.println("parallel prefix for complete array");
Arrays.parallelPrefix(dbNum1, dbOpt);
DoubleConsumer dbCon = d -> System.out.print(d+" ");
Arrays.stream(dbNum1).forEach(dbCon);
System.out.println("\nparallel prefix for array from index 1 to 4");
double[] dbNum2 = {3.2,4.1,2.2,5.4,1.2,6.4,3.2};
Arrays.parallelPrefix(dbNum2, 1, 4, dbOpt);
Arrays.stream(dbNum2).forEach(dbCon);
}
}
parallel prefix for complete array 3 12 24 120 120 720 2160 parallel prefix for array from index 1 to 4 3 4 8 40 1 6 3 parallel prefix for complete array 3.2 7.3 9.5 14.9 16.1 22.5 25.7 parallel prefix for array from index 1 to 4 3.2 4.1 6.3 11.7 1.2 6.4 3.2
