Thread Programming

Question

Can anybody answer me the foolwing questions?
1. How do I use the methods notify, notifyAll() in class Object?
Are they used to wake up the threads who are waiting on the object?
2. What means the keyword synchronized?
I heard about a lock on a object. Can you explain me, please.
3. There is also the possibility to use synchronized with methods.
Where is the difference?
4. How can I use the methods interrupted() and isInterrupted() in the Thread class?
What do they do?
Thanks in advance
Djamal

Answer 1

Can anybody answer me the foolwing questions?
1. How do I use the methods notify, notifyAll() in
class Object?notifyAll() will wake up all threads "waiting" for the objects lock you called it on. notify() will only wake up one (it's random)
Are they used to wake up the threads who are
re waiting on the object?
2. What means the keyword synchronized?synchronized is used to prevent concurrent access to a block of code (only one thread at a time) When you enter a synchronized block you aquire the lock for an object. A thread must aquire the lock before entering the block. Hence.. one thread at a time
I heard about a lock on a object. Can you explain
ain me, please.
3. There is also the possibility to use synchronized
with methods.methods can be synchronized, as can smaller code blocks.
Where is the difference?no difference only convinence
4. How can I use the methods interrupted() and
isInterrupted() in the Thread class?
What do they do?interrupt() attempts to interrupt the thread it is called on. It it used in a multitude of ways.
Thanks in advance
Djamalalso.. "The" book on Threads in java
http://java.sun.com/docs/books/cp/
And Doug Lea's site
http://gee.cs.oswego.edu/
You need to understand the design before you can code this stuff correcty. Also JSR 166 will be basically Doug Lea's concurrent package as java.util.concurrent.