mutithread.java

// Java program to illustrate  
// ThreadPool
package com.company;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.TimeUnit;

// Task class to be executed (Step 1) 
class Task implements Runnable
{
    private List<Integer> l;
    private ReentrantLock lock;

    public Task(List<Integer> l, ReentrantLock lock)
    {
        this.l = l;
        this.lock = lock;
    }

    // Prints task name and sleeps for 1s 
    // This Whole process is repeated 5 times
    @Override
    public void run()
    {
        for (int i = 0; i < 10000; i++)
        {
            lock.lock();
            int temp = l.get(0);
            lock.unlock();
            temp += 1;
            lock.lock();
            l.set(0, temp);
            lock.unlock();
        }
    }
}

public class Main
{
    // Maximum number of threads in thread pool
    static final int MAX_T = 2;

    public static void main(String[] args)
    {
        List<Integer> l = new ArrayList<>();
        ReentrantLock lock = new ReentrantLock();
        l.add(0);

        // creates five tasks
        Runnable r1 = new Task(l, lock);
        Runnable r2 = new Task(l, lock);

        // creates a thread pool with MAX_T no. of
        // threads as the fixed pool size(Step 2) 
        ExecutorService pool = Executors.newFixedThreadPool(MAX_T);

        // passes the Task objects to the pool to execute (Step 3) 
        pool.execute(r1);
        pool.execute(r2);
//        pool.execute(r3);
//        pool.execute(r4);
//        pool.execute(r5);

        // pool shutdown ( Step 4) 
        pool.shutdown();
        try {
            pool.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS);
        } catch (InterruptedException e) {
            System.out.println(e);
        }
        System.out.println(l.get(0));
    }
}