Java Thread Pool: Efficient Multithreading with Reusable Worker Threads

import java.util.concurrent.ExecutorService;  
import java.util.concurrent.Executors;  

class WorkerThread implements Runnable {  
    private String message;  
    public WorkerThread(String s){  
        this.message=s;  
    }  
    public void run() {  
        System.out.println(Thread.currentThread().getName()+" (Start) message = "+message);  
        processMessage(); // call processMessage method that sleeps the thread for 2 seconds  
        System.out.println(Thread.currentThread().getName()+" (End)"); // prints thread name  
    }  
    private void processMessage() {  
        try { Thread.sleep(2000); } catch (InterruptedException e) { e.printStackTrace(); }  
    }  
}  
        

public class TestThreadPool {  
    public static void main(String[] args) {  
        ExecutorService executor = Executors.newFixedThreadPool(5); // creating a pool of 5 threads  
        for (int i = 0; i < 10; i++) {  
            Runnable worker = new WorkerThread("" + i);  
            executor.execute(worker); // calling execute method of ExecutorService  
        }  
        executor.shutdown();  
        while (!executor.isTerminated()) { }  

        System.out.println("Finished all threads");  
    }  
}
        

import java.util.Date;  
import java.util.concurrent.ExecutorService;  
import java.util.concurrent.Executors;  
import java.text.SimpleDateFormat;  

class Tasks implements Runnable {  
    private String taskName;  

    public Tasks(String str) {  
        taskName = str;  
    }  

    public void run() {  
        try {  
            for (int j = 0; j <= 5; j++) {  
                if (j == 0) {  
                    Date dt = new Date();  
                    SimpleDateFormat sdf = new SimpleDateFormat("hh : mm : ss");  
                    System.out.println("Initialization time for the task name: "+ taskName + " = " + sdf.format(dt));  
                } else {  
                    Date dt = new Date();  
                    SimpleDateFormat sdf = new SimpleDateFormat("hh : mm : ss");  
                    System.out.println("Time of execution for the task name: " + taskName + " = " +sdf.format(dt));  
                }  
                Thread.sleep(1000); // 1000ms = 1 sec  
            }  
            System.out.println(taskName + " is complete.");  
        } catch (InterruptedException ie) {  
            ie.printStackTrace();  
        }  
    }  
}  
        

public class ThreadPoolExample {  
    static final int MAX_TH = 3; // Maximum number of threads in the thread pool  
    
    public static void main(String[] args) {  
        Runnable rb1 = new Tasks("task 1");  
        Runnable rb2 = new Tasks("task 2");  
        Runnable rb3 = new Tasks("task 3");  
        Runnable rb4 = new Tasks("task 4");  
        Runnable rb5 = new Tasks("task 5");   
        
        ExecutorService pl = Executors.newFixedThreadPool(MAX_TH); // creating a thread pool with MAX_TH number of threads  
        
        pl.execute(rb1);  
        pl.execute(rb2);  
        pl.execute(rb3);  
        pl.execute(rb4);  
        pl.execute(rb5);  
        
        pl.shutdown(); // pool is shutdown  
    }  
}