TestingThreads

public class TestingMatrixThreads {

    public static void main(String[] arr) throws InterruptedException {

        int[][] a = new int[67][6];
        // class.Count works with class.Matrix, that's why I've made it this way
        Matrix m = new Matrix(a);
        m.start();

        Thread.sleep(1000); // Here comes the BIG question -> how to avoid these
                            // manually created pauses

        Count c;
        Thread t;
        // Creating new threads for each row of the matrix
        for (int i = 0; i < Matrix.matr.length; i++) {
            c = new Count(i);
            t = new Thread(c);
            t.start();

        }

        //Again - the same question
        System.out.println("Main - Sleep!");
        Thread.sleep(50);
        System.out.println("\t\t\t\t\tMain - Alive!");

        int sum = 0;
        for (int i = 0; i < Count.encounters.length; i++) {
            System.out.println(i + "->" + Count.encounters[i]);
            sum += Count.encounters[i];
        }
        System.out.println("Total numbers of digits: " + sum);

    }

}

class Count implements Runnable {

    int row;
    public static int[] encounters = new int[10]; // here I store the number of each digit's(array's index) encounters

    public Count(int row) {
        this.row = row;
    }

    public synchronized static void increment(int number) {
        encounters[number]++;
    }

    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName() + ", searching in row " + row + " STARTED");

        for (int col = 0; col < Matrix.matr[0].length; col++) {
            increment(Matrix.matr[row][col]);
        }

        try {
            Thread.sleep(1); // If it's missing threads are starting and stopping consequently
        } catch (InterruptedException e) {
        }
        System.out.println(Thread.currentThread().getName() + " stopped!");
    }

}


class Matrix extends Thread {

    static int[][] matr;

    public Matrix(int[][] matr) {
        Matrix.matr = matr;
    }

    @Override
    public void run() {
        //print();
        fill();
        System.out.println("matrix filled");
        print();
    }

    public static void fill() {
        for (int i = 0; i < matr.length; i++) {
            for (int j = 0; j < matr[0].length; j++) {
                matr[i][j] = (int) (Math.random() * 10);
            }
        }
    }

    public static void print() {
        for (int i = 0; i < matr.length; i++) {
            for (int j = 0; j < matr[0].length; j++) {
                System.out.print(matr[i][j] + " ");
            }
            System.out.println();
        }
    }


}