Question

public class ProductThread {

static class ProductThreads extends Thread{

private int begin, end;

int[] v1, v2;

long ris;

public ProductThreads(String name, int [] v1, int [] v2, int begin, int end) {

setName(name);

this.v1 = v1;

this.v2 = v2;

this.begin = begin;

this.end = end;

this.ris = 0;

}

public void run() {

System.out.println("Thread " + Thread.currentThread().getName() + "[" + begin + "," + end + "] started");

ris = 1;

for(int i = begin; i <= end; i++)

ris *= v1[i] * v2[i];

System.out.println("Thread " + Thread.currentThread().getName() + "[" + begin + "," + end + "] completed");

}//run

public long getResult() {

return ris;

}

}//ProductThread

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

int [] a = {1,2,3,4,5,6,7,8,9,10};

int [] b = {1,2,3,4,5,6,7,8,9,19};

System.out.print("A = " );

print(a);

System.out.print("B = " );

print(b);

System.out.println();

//create threads

ProductThreads t0 = new ProductThreads("T0", a, b, 0, 2);

ProductThreads t1 = new ProductThreads("T1", a, b, 3, 5);

ProductThreads t2 = new ProductThreads("T1", a, b, 6, 9);

//start threads

t0.start();

t1.start();

t2.start();

//wait for completion of threads

t0.join();

t1.join();

t2.join();

//computation of final result

long result = 1;

System.out.println("T0 result= " + t0.getResult());

System.out.println("T1 result= " + t1.getResult());

System.out.println("T2 result= " + t2.getResult());

result *= t0.getResult() * t1.getResult() * t2.getResult();

System.out.println();

//final statement to be printed

System.out.println("Final Results = " + t0.getResult() + " * " + t1.getResult() + " * " + t2.getResult() + "= " + result);

}

static void print(int[] v) {

System.out.print("[");

for (int i = 0; i < v.length; i++) {

System.out.print(v[i] + " ");

System.out.println("]");

}

}

}

Using the same type of multithreading, I need to create a simple program that generates the factorial of a number, but splits up the calculation in multiple threads.

For instance, 5! = 5 * 4 * 3 * 2 * 1 so the threads would split the calculation up. Ex: T1 = 5 * 4 * 3 + T2 = 2 * 1

Answer 1

import java.util.Scanner;

public class ProductThread {

   static class ProductThreads extends Thread{

       private int begin, end;
       private long ris;
      
       public ProductThreads(String name,int begin, int end) {
           setName(name);
           this.begin = begin;
           this.end = end;
           this.ris = 1;
       }

       public void run() {
           System.out.println("Thread " + Thread.currentThread().getName() + "[" + begin + "," + end + "] started");
           for(int i = begin; i >= end; i--)
               ris *= i;
           System.out.println("Thread " + Thread.currentThread().getName() + "[" + begin + "," + end + "] completed");
       }//run

       public long getResult() {
           return ris;
       }
   }//ProductThread

   public static void main(String[] args) throws InterruptedException {
  
       System.out.print("Enter the value for factorial : ");
      
       Scanner sc=new Scanner(System.in);
       int value;
       value=sc.nextInt();
       sc.close();
      
       //create threads
  
       // split value and set range
       // value to 2*value/3 , (2*value/3-1) to value/3 , (value/3-1) to 1
      
       ProductThreads t0 = new ProductThreads("T0", value, 2*value/3);
       ProductThreads t1 = new ProductThreads("T1",2*value/3-1, value/3);
       ProductThreads t2 = new ProductThreads("T2", value/3-1, 1);
      
       //start threads
      
       t0.start();
       t1.start();
       t2.start();
  
       //wait for completion of threads
      
       t0.join();
       t1.join();
       t2.join();
      
       //computation of final result
      
       long result = 1;
       System.out.println("T0 result= " + t0.getResult());
       System.out.println("T1 result= " + t1.getResult());
       System.out.println("T2 result= " + t2.getResult());
       result *= t0.getResult() * t1.getResult() * t2.getResult();
       System.out.println();
      
       //final statement to be printed
      
       System.out.println("Final Results = " + t0.getResult() + " * " + t1.getResult() + " * " + t2.getResult() + "= " + result);
   }
  
}