Sample multithreading program using Callable Interface

Step 1: Create “MainThread.java” and paste the below code,

package com.ngdeveloper;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import runnableandcallable.CallingThread;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class MainThread{
private static ExecutorService service = Executors.newFixedThreadPool(10); //connection pool

@SuppressWarnings("unchecked")
public static void main(String[] args) throws InterruptedException {

List<CallingThread> threads = new ArrayList<CallingThread>(); //ArrayList to store the threads with CallingThread Type
CallingThread ct = null;

for(int i=1;i<=5;i++){ // 5 threads are created
ct = new CallingThread(i); //calling CallingThread constructor of the CallingThread class.
threads.add(ct); // Storing the threads with theirs tasks.
}
service.invokeAll((Collection<? extends Callable<CallingThread>>) threads); //invoking all the threads using connection pool
}
}

Step 2: Create “CallingThread.java” and paste the below code,

package com.ngdeveloper;

import java.util.concurrent.Callable;
import runnableandcallable.Businessprogram;

@SuppressWarnings("rawtypes")
public class CallingThread implements Callable{
int x;
Businessprogram bp = new Businessprogram();
public CallingThread(int x) {
this.x=x;
}

@Override
public Object call() throws Exception {
bp.Add();
//created thread calls the Add funcion of Businessprogram class. (5 times it called, because in the MainThread class we have created 5 threads
System.out.println("Thread No "+x); //
return x; //return statement is mandatory for the call method.
}

}

Step 3: Create the “Businessprogram.java” and paste the below code,

package com.ngdeveloper;

public class Businessprogram {
public int Add(){
int a=10;
int b=20;
System.out.println("Total =" +(a+b));
return (a+b);
}
}

Step 4: Run the MainThread.java program.

Ouput:

Total =30 (you will get five times, since we have created 5 threads here).

Note: Program explanations are given as comments in the respective files.

Thanks for reading this post……..!!!