This week's book giveaway is in the NodeJS forum.
We're giving away four copies of Serverless Applications with Node.js and have Slobodan Stojanovic & Aleksandar Simovic on-line!
See this thread for details.
Win a copy of Serverless Applications with Node.js this week in the NodeJS forum!
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other all forums
this forum made possible by our volunteer staff, including ...
  • Campbell Ritchie
  • Liutauras Vilda
  • Bear Bibeault
  • Jeanne Boyarsky
  • paul wheaton
  • Junilu Lacar
  • Paul Clapham
  • Knute Snortum
Saloon Keepers:
  • Stephan van Hulst
  • Ron McLeod
  • Tim Moores
  • salvin francis
  • Carey Brown
  • Tim Holloway
  • Frits Walraven
  • Vijitha Kumara

Lock Mechanism ?  RSS feed

Ranch Hand
Posts: 53
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

class ThreadA {
public static void main(String [] args) {
ThreadB b = new ThreadB();
synchronized(b) {
try {
System.out.println("Waiting for b to complete...");
} catch (InterruptedException e) {}
System.out.println("Total is: " +;
class ThreadB extends Thread {
int total;
public void run() {
synchronized(this) {
for(int i=0;i<100;i++) {
total += i;

Can somebody please explain the lock mechanism in the above code ?

Ranch Hand
Posts: 516
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

check the following code (your code) with comments.
Please read the comments in the numerated order (1-2-3-4-5-6-7)

In other words, the synchronize ensure that only a single thread can synchronize and execute inside the block.
The "wait" will make the thread wait until the other thread notify it, and also release the "lock" on the synchronized object.
You cannot "wait" or "notify" outside of a synchronized block.

Anyone else feel free to provide more or better details, it is not too easy to describe

[ January 22, 2008: Message edited by: Alex Belisle Turcot ]
Message for you sir! I think it is a tiny ad:
global solutions you can do in your home or backyard
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!