Tasks.java

class Tasks {
    public static void main(String[] args) {
        Tasks t = new Tasks();
        Task1 t1 = new Task1();
        Task2 t2 = new Task2();
        Task3 t3 = new Task3();

        t1.start();
        t2.start();
        t3.start();
    }
}

class Task1 extends Thread {
    public void run() {
        System.out.println("T1 is running on thread " + Thread.currentThread().getName());
        int n = computePrimeNumber();
        putPrimeNumberInDatabase(n);
    }

    public int computePrimeNumber() {
        System.out.println("Computed prime number 17");
        return 17;
    }

    public void putPrimeNumberInDatabase(int n) {
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Successfully put " + n + " in the database");
    }
}

class Task2 extends Thread {
    public void run() {
        System.out.println("T2 is running on thread " + Thread.currentThread().getName());
        int n = computePrimeNumber();
        putPrimeNumberInDatabase(n);
    }

    public int computePrimeNumber() {
        System.out.println("Computed prime number 23");
        return 23;
    }

    public void putPrimeNumberInDatabase(int n) {
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Successfully put " + n + " in the database");
    }
}

class Task3 extends Thread {
    public void run() {
        System.out.println("T3 is running on thread " + Thread.currentThread().getName());
        int n = computePrimeNumber();
        putPrimeNumberInDatabase(n);
    }

    public int computePrimeNumber() {
        System.out.println("Computed prime number 13");
        return 13;
    }

    public void putPrimeNumberInDatabase(int n) {
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Successfully put " + n + " in the database");
    }
}

/*
Output:

T1 is running on thread Thread-0
T3 is running on thread Thread-2
T2 is running on thread Thread-1
Computed prime number 13
Computed prime number 17
Computed prime number 23
Successfully put 17 in the database
Successfully put 23 in the database
Successfully put 13 in the database
*/