// Java Program to Demonstrate the Lazy initialization
// non-thread-safe

// Importing input output classes
import java.io.*;

// Class 1
// Helper class behaving as a Singleton Class
class Table1 {

    // Lazy Instantiation also referred as On-demand
    // Instantiation

    // Private static member variables
    private static Table1 table1;
    private static String customerNameBooked;

    // Constructor of this class which is private
    // To display customer name whom table1 is booked for
    private Table1(String customerName)
    {

        // Print and display the customer name
        System.out.println("Table1 is now Booked for "
                           + customerName);

        // Booking under the same person
        customerNameBooked = customerName;
    }

    // Non thread-safe block of code to
    // demonstrate thread safe with updation in its methods

    // Method 1
    // To get the status of table
    public static Table1
    getTable1Instance(String customerName)
    {

        // If table is nor book/reserve
        if (table1 == null) {

            // book under the derired customer name
            table1 = new Table1(customerName);
        }

        // If table is already booked
        else

            // Calling th method
            tableBooked(customerName);

        return table1;
    }

    // Method 2 (auxiliary)
    // To display whom table is booked for
    private static void tableBooked(String customerName)
    {

        // Print the custom name and
        // name of customer under which table i booked
        System.out.println(
            "Sorry " + customerName
            + " Table 1 is already Booked for "
            + customerNameBooked);
    }
}

// Class 2
// Main class
public class Restaurant {

    // Main driver method
    public static void main(String args[])
    {

        // Now we will be creating various threads as
        // customer who wish to book Table1 in Restaurant

        // Creating first customer(Thread-0)
        // using Runnable interface
        Thread t1 = new Thread(new Runnable() {
            // run() method for the thread
            public void run()
            {

                // Getting the table status
                Table1 customer1
                    = Table1.getTable1Instance("ABC");
            }
        });

        // Similarly repeating same for other customers

        // Again creating second customer(Thread-1)
        // using Runnable interface
        Thread t2 = new Thread(new Runnable() {
            // run() method for this thread
            public void run()
            {

                Table1 customer2
                    = Table1.getTable1Instance("XYZ");
            }
        });

        // Creating third customer(Thread-2)
        // using Runnable interface
        Thread t3 = new Thread(new Runnable() {
            // run() method for this thread
            public void run()
            {

                Table1 customer3
                    = Table1.getTable1Instance("PQR");
            }
        });

        // Now starting the threads
        // using start() method
        t1.start();
        t2.start();

        // Try block to check for exceptions if any
        try {

            // Intentionally having a Thread.sleep(1000) to
            // demonstrate not Thread-safe environment
            Thread.sleep(1000);
        }

        // Catch block to handle the exceptions
        catch (InterruptedException e) {
        }

        // Now starting the last thread via same means
        t3.start();
    }
}