Question

Java

Question: Write a multithread Java program that performs matrix multiplication. In the program, you need to calculate each element in the result matrix in a separate thread. The code should be generic with regard to matrix size. The sizes of three matrices should be stored in variable and used. The two operand matrices and the result matrix should be printed.

Thanks

Answer 1

ANSWER:

import java.util.Random;

class MatrixMultiplier extends Thread {
    private int a[][], b[][];
    private int i;
    private int j;
    private volatile int value = 0;

    public MatrixMultiplier(int a[][], int b[][], int i, int j) {
        this.a = a;
        this.b = b;
        this.i = i;
        this.j = j;
    }

    @Override
    public void run() {
        int n = b.length;
        for (int k = 0; k < n; k++) {
            value += a[i][k] * b[k][j];
        }
    }

    public int getValue() {
        return value;
    }
}
public class ThreadedMatrixMultiplication {


    public static void initializeMatrix(int mat[][]) {
        // to get new random number
        Random r = new Random();

        for (int i = 0; i < mat.length; i++) {
            for (int j = 0; j < mat[i].length; j++) {
                mat[i][j] = Math.abs(r.nextInt()) % 100;
            }
        }
    }

    public static void printMatrix(int mat[][]) {
        for (int i = 0; i < mat.length; i++) {
            for (int j = 0; j < mat[i].length; j++) {
                System.out.printf("%10d", mat[i][j]);
            }
            System.out.println();
        }
    }

    public static void main(String[] args) {
        int m = 4;
        int n = 5;
        int p = 3;

        int a[][] = new int[m][n];
        int b[][] = new int[n][p];
        int product[][] = new int[m][p];

        initializeMatrix(a);
        initializeMatrix(b);

        // multiply both matrix
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < p; j++) {
                MatrixMultiplier t = new MatrixMultiplier(a, b, i, j);
                t.start();
                try {
                    t.join();
                    product[i][j] = t.getValue();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }

        System.out.println("Matrix 1: ");
        printMatrix(a);
        System.out.println("
Matrix 2: ");
        printMatrix(b);
        System.out.println("

Product: ");
        printMatrix(product);
    }

}