JAVA EE: Java Tutorial: Java Synchronization (Synchronization in java

Thursday 9 February 2017

Java Tutorial: Java Synchronization (Synchronization in java | synchronized block in java_V4)

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Java Tutorial: Java Synchronization (Synchronization in java | synchronized block in java_V4)

DisplayCounter.java

public class DisplayCounter
{

    public void printCount()
    {
        /*
         * synchronized block.
         */
        //synchronized (this)
        //{
            try
            {
                System.out.println("Thread Name = " + Thread.currentThread().getName());
                for (int i = 5; i > 0; i--)
                {
                    System.out.println("Counter   ---   " + i);
                    Thread.sleep(200);
                }
                System.out.println();               
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
        //}

    }
}

DisplayThread.java

public class DisplayThread extends Thread
{
    private DisplayCounter dc;

    public DisplayThread(String name, DisplayCounter dc)
    {
        super.setName(name);
        this.dc = dc;
    }

    public void run()
    {
        dc.printCount();
    }

}

SynchronizationDemo.java

public class SynchronizationDemo
{
    public static void main(String[] args)
    {
        DisplayCounter displayCounter = new DisplayCounter();

        DisplayThread thread1 = new DisplayThread("Thread1", displayCounter);
        DisplayThread thread2 = new DisplayThread("Thread2", displayCounter);

        thread1.start();
        thread2.start();
    }
}

Output

-------------------------------------
If printCount method has synchronized block,
then below will be the output:
-------------------------------------

Thread Name = Thread1
Counter   ---   5
Counter   ---   4
Counter   ---   3
Counter   ---   2
Counter   ---   1

Thread Name = Thread2
Counter   ---   5
Counter   ---   4
Counter   ---   3
Counter   ---   2
Counter   ---   1

-----------------------------------------
If printCount method does not have synchronized block,
then below will be the output:
-----------------------------------------
Thread Name = Thread1
Thread Name = Thread2
Counter   ---   5
Counter   ---   5
Counter   ---   4
Counter   ---   4
Counter   ---   3
Counter   ---   3
Counter   ---   2
Counter   ---   2
Counter   ---   1
Counter   ---   1