Question 9
Sybex Java OCP 8 Study Guide Typo Chapter 7 page 396

in the book is
int result = t1.fork().join();
Integer sum = pool.invoke(task);

It needs explicit cast because it is an Object and it gives compiler error

int result = (int) t1.fork().join();
Integer sum = (Integer) pool.invoke(task);

import java.util.concurrent.*; class FindMin extends RecursiveTask {    private Integer[] elements;    private int a;    private int b;    public FindMin(Integer[] elements, int a, int b) {        this.elements = elements;        this.a = a;        this.b = b;    }    public Integer compute() {        if ((b - a) < 2)            return Math.min(elements[a], elements[b]);        else {            int m = a + ((b-a) /2);            System.out.println(a + "," + m + "," + b);            FindMin t1 = new FindMin(elements, a, m);            int result = (int) t1.fork().join();            return Math.min(new FindMin(elements, m, b).compute(), result);        }    }        public static void main(String[] args) throws InterruptedException, ExecutionException {        Integer[] elements = new Integer[]{8, -3, 2, -54};        FindMin task = new FindMin(elements, 0, elements.length-1);        ForkJoinPool pool = new ForkJoinPool(1);        //public ForkJoinPool(int parallelism – the parallelism level)        Integer sum = (Integer) pool.invoke(task);        System.out.println("Min: " + sum);    } } //0,1,3 //1,2,3 //Min: -54

Agreed. Logged as errata crediting you. Thanks!