SYNCHONIZED BLOCK NOTES IN JAVA

Synchronized Block in Java

Synchronized block can be used to perform synchronization on any specific resource
of the method.

Suppose we have 50 lines of code in our method, but we want to synchronize only 5
lines, in such cases, we can use synchronized block.

If we put all the codes of the method in the synchronized block, it will work same as
the synchronized method.

Points to Remember

o Synchronized block is used to lock an object for any shared resource.
o Scope of synchronized block is smaller than the method.
o A Java synchronized block doesn't allow more than one JVM, to provide access
control to a shared resource.
o The system performance may degrade because of the slower working of
synchronized keyword.
o Java synchronized block is more efficient than Java synchronized method.

Syntax

1. synchronized (object reference expression) {
2. //code block
3. }

Example of Synchronized Block

Let's see the simple example of synchronized block.

TestSynchronizedBlock1.java

1. class Table
2. {
3. void printTable(int n){
4. synchronized(this){//synchronized block
5. for(int i=1;i<=5;i++){
6. System.out.println(n*i);
7. try{
8. Thread.sleep(400);

, 9. }catch(Exception e){System.out.println(e);}
10. }
11. }
12. }//end of the method
13. }
14.
15. class MyThread1 extends Thread{
16. Table t;
17. MyThread1(Table t){
18. this.t=t;
19. }
20. public void run(){
21. t.printTable(5);
22. }
23.
24. }
25. class MyThread2 extends Thread{
26. Table t;
27. MyThread2(Table t){
28. this.t=t;
29. }
30. public void run(){
31. t.printTable(100);
32. }
33. }
34.
35. public class TestSynchronizedBlock1{
36. public static void main(String args[]){
37. Table obj = new Table();//only one object
38. MyThread1 t1=new MyThread1(obj);
39. MyThread2 t2=new MyThread2(obj);
40. t1.start();
41. t2.start();
42. }
43. }

Output: