Threads - Задача 2

import java.util.Random;

public class TenThreads {
    private static class WorkerThread implements Runnable {
        int max = Integer.MIN_VALUE;
        int[] ourArray;

        public WorkerThread(int[] ourArray) {
            this.ourArray = ourArray;
        }

        // Find the maximum value in our particular piece of the array
        public void run() {
            for (int i = 0; i < ourArray.length; i++)
                max = Math.max(max, ourArray[i]);
        }

        public int getMax() {
            return max;
        }
    }

    public static void main(String[] args) {
        WorkerThread[] threads = new WorkerThread[20];
        Thread demThreads[] = new Thread[20];


        int[][] bigMatrix = getBigHairyMatrix();
        int max = Integer.MIN_VALUE;

        // Give each thread a slice of the matrix to work with
        for (int i = 0; i < 10; i++) {
            threads[i] = new WorkerThread(bigMatrix[i]);
            demThreads[i] = new Thread(threads[i]);
            demThreads[i].start();
        }

        // Wait for each thread to finish
        try {
            for (int i = 0; i < 10; i++) {
                demThreads[i].join(); // why is this needed
                max = Math.max(max, threads[i].getMax());
            }
        } catch (InterruptedException e) {
            // fall through
        }

        System.out.println("Maximum value was " + max);
    }

    static int[][] getBigHairyMatrix() {
        int x = 100;
        int y = 100;

        int[][] matrix = new int[x][y];
        Random rnd = new Random();

        for (int i = 0; i < x; i++)
            for (int j = 0; j < y; j++) {
                matrix[i][j] = rnd.nextInt();
            }

        return matrix;
    }

}